Self-Healing Electronic Materials for a Smart and Sustainable Future

Subscriber access provided by Kaohsiung Medical University

Self-Healing Electronic Materials for a Smart and Sustainable Future Yu Jun Tan, Jiake Wu, Hanying Li, and Benjamin C.K. Tee ACS Appl. Mater. Interfaces, Just Accepted Manuscript • DOI: 10.1021/acsami.7b19511 • Publication Date (Web): 18 Apr 2018 Downloaded from http://pubs.acs.org on April 18, 2018

Just Accepted “Just Accepted” manuscripts have been peer-reviewed and accepted for publication. They are posted online prior to technical editing, formatting for publication and author proofing. The American Chemical Society provides “Just Accepted” as a service to the research community to expedite the dissemination of scientific material as soon as possible after acceptance. “Just Accepted” manuscripts appear in full in PDF format accompanied by an HTML abstract. “Just Accepted” manuscripts have been fully peer reviewed, but should not be considered the official version of record. They are citable by the Digital Object Identifier (DOI®). “Just Accepted” is an optional service offered to authors. Therefore, the “Just Accepted” Web site may not include all articles that will be published in the journal. After a manuscript is technically edited and formatted, it will be removed from the “Just Accepted” Web site and published as an ASAP article. Note that technical editing may introduce minor changes to the manuscript text and/or graphics which could affect content, and all legal disclaimers and ethical guidelines that apply to the journal pertain. ACS cannot be held responsible for errors or consequences arising from the use of information contained in these “Just Accepted” manuscripts.

is published by the American Chemical Society. 1155 Sixteenth Street N.W., Washington, DC 20036 Published by American Chemical Society. Copyright © American Chemical Society. However, no copyright claim is made to original U.S. Government works, or works produced by employees of any Commonwealth realm Crown government in the course of their duties.

Page 1 of 57 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

ACS Applied Materials & Interfaces

Self-Healing Electronic Materials for a Smart and Sustainable Future Yu Jun Tan1+, Jiake Wu2+, Hanying Li2, Benjamin C.K. Tee1,3,4* 1

Biomedical Institute for Global Health and Research (BIGHEART), National

University of Singapore, Singapore 2

Zhejiang University, Hangzhou, China

3

Materials Science and Engineering Department, National University of Singapore,

Singapore 4

Institute of Materials Research and Engineering, Agency for Science Technology and

Research, Singapore +

Both authors contributed equally to this work

*

Author to whom correspondence should be addressed: [email protected]

Keywords: self-healing, sustainability, polymers, composite materials, devices

Abstract

The survivability of living organisms relies critically on their ability to self-heal from damage in unpredictable situations and environmental variability. Such abilities are most important in external facing organs such as the mammalian skin. However, the properties of bulk elemental materials are typically unable to perform self-repair. Consequently, most conventional smart electronic devices today are not designed to repair themselves when damaged. Thus, inspired by the remarkable capability of self-healing in natural systems, smart self-healing materials are being intensively researched to mimic natural systems to have the ability to partially or 1

ACS Paragon Plus Environment

ACS Applied Materials & Interfaces 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 2 of 57

completely self-repair damages inflicted on them. This exciting area of research could potentially power a sustainable and smart future.

1

Introduction

One of the most intriguing and useful features of living organisms is their continuous self-healing ability after suffering from damage. Human skin, for example, heals from wounds of various degrees.1 In contrast, the properties of a majority of synthesized materials degrade over time due to fatigue, corrosion or damage incurred during operation. Therefore, inspired by the remarkable capability of nature, smart self-healing materials are being intensively researched to mimic natural systems to have the ability to partially or completely self-repair damages inflicted on them.2–8

Current self-healing systems can be broadly classified into two groups, i.e. the ‘non-autonomic’ and the ‘autonomic’ strategies, according to the trigger requirements and the nature of self-healing process. Non-autonomic systems require external triggers, e.g. light, heat or chemicals for self-healing. On the other hand, autonomic systems initiate the self-healing process upon damage. Self-healing materials can be also be conceptually divided into ’extrinsic’ and ‘intrinsic’ self-healing,4–8 which will be discussed in Section 2.

Recent development of self-healing materials towards the field of organic electronics have been successfully demonstrated in numerous advanced applications such as smart wearables and stretchable devices.6,9–12 In the last few decades, technology for fabricating organic electronics has been progressing rapidly due to the wide-range of

2


Page 3 of 57 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


substrates compatibility and excellent mechanical flexibility. 11,13–15 It shows potential to lower the costs of materials and their processing, while maintaining suitably sufficient performance. However, stability and durability of the materials remain challenges to be resolved before these organic electronic devices become common in the market. For this reason, the self-healing materials for organic electronics is being researched upon, that may significantly improve the reliability and lifetime of devices.

Although there are technical challenges in integrating materials properties and electronic performance during self-healing processes, there have been advancements in the design and synthesis of self-healing conductors,9,14 polymeric materials,4,8 ceramics and concrete materials,7,16,17 and metals.7,18 In this review, we aim to provide a state-of-the-art overview of the self-healing electronic devices for various applications. These applications include sensors,19–25 Electronic skin (E-skin),26 supercapacitors,27–29 perovskite solar cells, and batteries

37,38

30–33

field-effect transistors (FETs),34–36

(Figure 1). Importantly, as Figure 1 shows, conducting materials

play an integral role in enabling functional self-healing electronic devices.39

In the following sections, we first summarize the key developments of self-healing materials. In particular, we compare the different self-healing polymeric materials and examine the self-healing mechanisms of these materials. We also highlight some of the exciting advances on the self-healing devices. In the last section, we conclude this review by offering insights into the challenges and opportunities facing in this field.

3



2

Page 4 of 57

Advances in Self-Healing Materials

Polymeric materials are the most widely studied materials for self-healing behaviour. The large design space of polymer systems enables a plethora of creative ways to enable self-healing capabilities. For example, self-healing can be readily achieved by modification and functionalization of polymer systems that requires rather low temperature in their processing.8 Performances of the self-healing materials are often quantified by the “healing efficiency, η”, which is a measure of the restoration and recovery of a lost or degraded property or performance metric.40 Healing efficiency is defined by the ratio of changes in material properties: η =

௉౞౛౗ౢ౛ౚ ି௉೏ೌ೘ೌ೒೐೏ ௉౦౨౟౩౪౟౤౛ ି௉ౚ౗ౣ౗ౝ౛ౚ

, where P

is the material property of interest.40 2.1

Extrinsic self-healing polymers

Self-healing polymers can be divided into the extrinsic and the intrinsic self-healing polymers.4–7 They are categorized according to the strategies by which the healing functionality is integrated into the bulk material. Extrinsic self-healing materials themselves do not have self-healing capability. They contain external healing agents encapsulated in capsules or vascular network. Damage to the composite causes the capsules or vascular network to break, releasing the healing agents, healing the bulk materials and preventing damage propagation. In capsule-based self-healing materials, the healing agents are stored in capsules until damage triggers the healing. White and co-workers reported the first structural polymeric material that could autonomically heal cracks by incorporating a microencapsulated healing agent (Figure 2a, b).41 4


Page 5 of 57 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


Crack initiation in the matrix releases the dicyclopentadiene (DCPD) monomer encapsulated in microcapsules, releasing the monomer into the crack plane through capillary action. Subsequently, ring-opening metathesis polymerization initiated upon contacting with an embedded Ruthenium-based Grubbs' catalyst, thus healing the crack. Progressive development has been made since then in the encapsulation techniques, such as in situ,42 interfacial,43 and meltable dispersion44 for capsule-based self-healing materials. Healing agents and catalysts can be sequestered in four ways: capsule-catalyst, multicapsule, latent functionality and phase-separated, which were illustrated in White’s review.40 Correspondingly, many other healing agents and catalysts

have

been

achieved,

for

instance,

isocyanates,45

linseed

oil,46

polydimethylsiloxane (PDMS),47 and epoxy resins.48 The capsule-based healing concept has been commonly employed as the fabrication is straightforward by dispersing capsules inside a matrix. Nevertheless, the inherent drawback of capsule-based healing methods is the local function depletion after a single damage event.40

To overcome the disadvantages of the capsule-based healing, the vascular self-healing systems, where healing agents and catalysts are sequestered in networks in the form of capillaries or hollow channels, were developed. They were found to be capable of autonomously repair repeated damage events. White et al. developed the bio-inspired microvascular networks coating-substrate design (Figure 2c, d).49 Healing agents were continuously delivered to cracks via the three-dimensional (3D) microvascular

5



Page 6 of 57

network embedded in the substrate. Large-volume and repeatable self-healing could be obtained in their design. However, depletion of the embedded catalyst and the need to resupply multiple healing agents within these architectures would limit the healing ability. To overcome this limitation, White et al. further developed a two-part epoxy healing chemistry, containing photo-lithographically patterned isolated regions within the embedded microvascular network.50 They improved their design with 3D biomimetic coating/substrate interpenetrating microvascular network architecture and microvascular structural fiber-composites, finally gaining more than 30 repeated healing cycles. Subsequently, Williams et al. also demonstrated self-healing in sandwich composite configurations that contain either one-dimensional (1D) or two-dimensional (2D) fluidic networks.51 The vascular self-healing systems has significant advantages over the capsule-based systems, but one minor disadvantage is that it requires a rather complicated design and fabrication process of microvascular network. 2.2

Intrinsic self-healing polymers

Another possible strategy to enable self-healing capabilities in materials is to do so via ‘intrinsic’ mechanisms. Intrinsic self-healing materials do not need external healing agent. Multiple and repeatable healing events are feasible in these systems. They are more reliable and durable compared to the extrinsic self-healing materials. Intrinsic self-healing can be accomplished through inherent reversibility of molecular interactions of the matrix polymer, which avoid complex problems of healing-agents’

6


Page 7 of 57 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


integration and compatibility. Recent review papers have been published summarizing the self-healing mechanisms.4,7,40 Briefly, the mechanisms that have emerged are grouped into two categories, namely the physical molecular diffusion and the chemical bond interaction. Physical molecular diffusion based healing was demonstrated in compact polyelectrolyte complexes (CoPECs). Their healing strength depends on the salt concentration in the material. The higher the salt concentration, the greater the mobility of the chain segments; which leads to a faster chains diffusion and then a faster healing.

Chemical bond interaction based self-healing can be further divided into the covalent and the non-covalent bond interactions, and also the intermolecular forces (hydrogen bond, dipole-dipole and Van der Waal's interactions).8 Reversible covalent interaction, such

as

Diels-Alder

(DA)

reaction,

could

make

polymer

network

a

temperature-sensitive polymerization-depolymerization equilibrium.52,53 The thermal activated “re-mending” material system is based on the thermally reversible DA cycloaddition to synthesized highly cross-linked furan-maleimide polymers. Comparably, a crosslinked polyurethane containing aromatic pinacol as a reversible covalent bond provider was synthesized.54 In contrast to the covalent interaction, materials associated by noncovalent bonds, i.e. supramolecular polymers or gels, can self-heal with or without external stimuli. Supramolecular gels were formulated where the materials self-heal via reversible host–guest interactions without triggers.55,56 A self-healing rubbery polymeric material was synthesized by Leibler et al.57 The

7



Page 8 of 57

supramolecular rubber was derived from fatty acids and urea. The material self-heal when brought into contact at room temperature through the hydrogen bonds without the need to press strongly. Recently, Aida et al. developed a mechanically robust polymer material that is healable by compression. The amorphous materials have short polymer chains that allow substantial segmental motions, and have large number of less ordered hydrogen bonds. Similar to the Leibler’s supramolecular rubber, hydrogen bonds facilitate the healing of the materials.

58

Wang et al. developed a

Wolverine-inspired self-healing material which is transparent and stretchable.59 The material self-heals upon contact via ion-dipole interaction as shown in Figure 2e, f. Performance map for damage volume regimes of each approach was reported.40 Intrinsic self-healing systems can be used to heal small damages and can possibly self-heal at the molecular scale. On the contrary, vascular healing systems can heal large damage volumes and can potentially extend the upper limit of self-healing volume. The capsule-based self-healing systems lie in between the intrinsic and the vascular self-healing methods. Most approaches to self-healable materials require heating the damaged area to a temperature above its glass transition or melting temperature or exposing it to a plasticizing solvent,60,61 or applying mechanical force to heal the wound.5,6 In comparison, few self-healing systems are known in which defects can be healed upon some other external stimuli,62 including electricity,63,64 electromagnetic field,65 ballistic impact66,67 and light.68,69 Self-healing polymeric materials have been modified in different ways to meet the desired mechanical

8


Page 9 of 57 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


properties (strength, flexibility, and even stretchability), speed of self-healing, biocompatibility and optical properties for various applications. Next section of this review is devoted to the self-healing materials incorporated in electronic applications, which represent an emerging class of self-healable materials with fascinating electrical properties.

3

Self-healing Devices

Self-healing materials are being investigated for their use in construction and building, coatings, electronics and biomedical fields.

16,40,70

Recently, there has been intense

interest in incorporating self-healing materials into electronic and electrochemical devices, including sensors, E-skin, FETs, solar cells and supercapacitors. Apart from the devices being described in this section, self-healing materials are also involved in fabricating other electronic and electrochemical devices, such as batteries,37,38 dielectric actuators,71–73 and electrochemical sensors.74,75 3.1

Conductors

Conductive polymeric materials are essential in the development of organic electronic devices such as solar cells, sensors, displays, actuators and energy storage devices. Key requirement in developing self-healing conductors is to have a high conductivity retention after damage and healing, so that the devices remain functional. A straightforward strategy to fabricate self-healing conductors is to introduce dynamic reversible bonds into conductive polymers. Williams and co-workers synthesized an electrically conductive and self-healing organometallic polymer comprising 9



Page 10 of 57

N-heterocyclic carbenes and transition metals (Figure 3a, b).63 The reversible metal-carbon bonds led to dynamic equilibrium between the monomers and the organometallic polymer. The conductivity of the material was ~10−3 S cm−1. When cut by a sharp razor, the polymer could facilitate healing by heating to 150 °C in the presence of dimethyl sulfoxide (DMSO) vapour. Its poor conductivity and the requirement of a high temperature and a solvent vapour for healing limited its practical application as self-healing conductors. Thereafter, Yu et al. developed an autonomic self-healing hybrid gel based on self-assembled supramolecular gel and conductive nanostructured polypyrrole, in which the dynamic metal–ligand supramolecule facilitates the electrical self-healing property without any external stimuli. The conductivity of the gel was 0.12 S cm−1.76

An alternative way is to incorporate conductive materials, such as metallic particles, metallic nanowires, CNTs, graphene-based materials, liquid metals, and salts, into non-conductive self-healing polymers. The conductive materials should provide high conductivity while have good compatibility with the host self-healing polymer. Bao et al. was the first to report an electronic sensor skin (E-skin) that can repeatedly self-heal at room-temperature by using a supramolecular organic–inorganic composite.26 The Leibler’s supramolecular rubber described in previous section was chosen as the host polymer, and nickel microparticles (µNi particles) as the conductive fillers (Figure 3c). The electrical conductivity could reach up to 40 S cm-1 with 31% volume fraction of µNi particles (Figure 3d). On rupture, ∼90% of its

10


Page 11 of 57 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


original conductivity can be restored after 15 s of healing at room temperature (Figure 3e). The recoverability of mechanical properties of the material was high at room temperature, and fully recovered at 50 °C. The material can heal damage inflicted on it completely without scar as shown in Figure 3f. The material was explored for its use in E-Skin, which will be addressed in Section 3.2. Sun et al. reported the fabrication of a highly conductive self-healing conductor by casting the poly(vinylpyrrolidone) (PVPON)-decorated silver conductive nanowires (AgNWs) onto the polyelectrolyte multilayered (PEM) films.77 The self-healing PEM film consists of a layer-by-layer (LbL) assembly of branched poly(ethylenimine) (bPEI) and poly(acrylic acid)–hyaluronic acid (PAA–HA) blend, which can repair damages such as cracks and cuts in the presence of water. The hydrogen bonds between the carboxylic acid groups on the PEM film and the pyrrolidone groups on the PVPON-decorated AgNWs allows strong adhesion between these two layers. A light-emitting diode (LED) bulb was used to check the ability of the materials to restore its electrical conductivity after healing using deionized water at room temperature (Figure 4a). AgNWs/PEM films swell after the addition of water, causes the fractured surfaces to heal by reforming ionic bonds (Figure 4b, c).

Inspired by mussel, a tough polydopamine-graphene oxide-polyacrymide (PDA– pGO–PAM) conductive hydrogel was reported that can self-heal, and self-adhere.78 PDA entangled reduced graphene oxide was well dispersed in the network and interweaved to form electronic pathway, gave rise to good conductivity. The

11



Page 12 of 57

unreduced graphene oxide together with PDA chains interacted with the PAM network via noncovalent interaction, including the hydrogen bonds and π–π stacking between free catechol groups of PDA chains and the electrostatic interactions between GO and PAM, resulting in self-healability and self-adhesiveness of the hydrogel. Dickey et al. fabricated stretchable wires by using the self-healing supramolecular rubber with liquid metal (Eutectic Gallium-Indium (EGaIn)) - filled microchannels (Figure 4d).79 The wires exhibited metallic conductivity, and can self-heal both mechanically and electrically after being ruptured completely.

White et al. came out with the first microcapsule healing system for the restoration of conductivity

in

mechanically

damaged

electronic

devices.80

Solutions

of

tetrathiafulvalene (TTF) and tetracyanoquinodimethane (TCNQ) in various solvents were separately encapsulated into poly(urea-formaldehyde) core–shell system. The conductive TTF-TCNQ charge-transfer salts (with high conductivity of ca. 400–500 S cm-1) formed rapidly upon rupture of the microcapsules. The salts would bridge the gaps and restore the electrical conductivity of the device. In another study, microencapsulated EGaIn liquid metal was patterned on gold (Au) lines.81 Both the encapsulation systems showed similar self-healing mechanism by releasing encapsulated liquid conductive materials to damaged sites and at the same time restore the electrical conductivity. They can rapidly re-establish the electrical performance of materials, however, as discussed in Section 2, they do not have ability to heal multiple times at the same site due to the depletion of self-healing agents. A

12


Page 13 of 57 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


transparent and highly stretchable self-healing material developed by Wang et al. as described in Section 2 is conductive.59 The ionic conductor was fabricated by mixing poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-co-HFP) and ionic liquid (salt). The material has ionic conductivity of 10-5 S cm-1. The material can self-heal at room temperature by ion-dipole interactions, where the healing can be expedited at higher temperature at 50 oC. A summary of various materials and composites that have been recently reported as self-healing conductors along with their corresponding healing mechanisms and electrical properties, are given in Table 1. 3.2

Sensors and E-Skins

Sensors are widely employed in our daily lives to detect and perceive external signals, e.g. physical (such as light, heat, humidity) or chemical (such as smoke) signals. They are the basis to achieve automatic detection and unmanned control for advanced electronics technology. For instance, most of the mobile devices these days like mobile phones, tablets and laptop computers have capacitive electrical touchscreens. However, they are highly fragile where accidental drop or scratching results in malfunction of the touch sensor. If self-healing sensors are utilized, we can potentially increase lifespan of such devices, especially for both functional (sensing ability) and aesthetic purposes.

Pei et al. fabricated a highly conductive, transparent and self-healing composite electrode by spray coating AgNWs percolation network on a DA cycloaddition polymer substrate.19 The composite film has an original resistance of 18 Ω/sq, which 13



Page 14 of 57

recovered to 21 Ω/sq after heating at 100 °C for 6 min by which the AgNWs reconnected. Capacitive touch screen sensors were constructed by laminating two transparent composite films with electrodes patterned in rows and columns. They were then overlaid on a LED display as shown in Figure 5a. A ‘smiley face’ was drawn and snapshot on the touch screen (Figure 5b). After damage, the touch sensing function recovered by heating at 80 °C for 30 s. The cutting-healing was tested and proven to be effective for up to 4 cycles, indicating that this healable touch sensor is useful for electronic displays. Ionic liquids usually have higher ionic conductivity at higher temperatures.82,83 Wang et

al.

took

advantage

of

1-Octyl-3-methylimidazolium

this

property,

assembled

hexafluorophosphate

ionic

([OMIm][PF6])

liquid

of

into

a

single-channel supramolecular network matrix for sensing application, which showed an increase in conductivity upon an increase in temperature.84 Subsequently, they prepared a self-healing near-infrared (NIR) sensor that was constructed by loading the acid-modified carbon nanotubes (acid-CNTs) with capability of photothermal conversion in the ionic liquid of [OMIm][PF6]. The obtained NIR light sensor can self-heal many times even when the fracture occurred at the same position. The results demonstrated that the combination of excellent thermo-sensitivity along with good conductivity of self-healing materials can be exploited in the production of the next-generation self-healing optoelectronics and sensors.

CNTs are quite favourable in hybrid self-healing CNTs/polymer materials due to their

14


Page 15 of 57 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


high electron conductivity and ease of functionalization.85,86 Zhang et al. demonstrated a strategy for fabricating humidity sensors by coupling a polymer network and the conductive single-walled carbon nanotubes (SWCNTs) through the host–guest

interactions.87

The

conductive

rubber-like

poly(2-hydroxyethyl

methacrylate) (PHEMA)-SWCNTs composite was prepared in a two-step process: 1) pyrene-modified β-cyclodextrin (Py-β-CD) was attached onto SWCNTs, and the Py-β-CD interact with an adamantine (Ad) modified 2-hydroxyethyl methacrylate (HEMA-AD)

through

host–guest

interactions;

2)

the

resultant

Py-β-CD-SWCNTs/HEMA-AD was cross-linked with HEMA monomer. The composites showed moisture absorption capacity under ambient condition due to the hydrophilicity of the hydroxyl groups existed in the PHEMA chains. The resistance of the polymer composites changed greatly after exposing to moisture, which makes them suitable for moisture sensing. Chen et al. employed functional CNTs networks on transparent, healable polyelectrolyte multi-layered films to obtain a chemical gas sensor device.20 After cutting a small gap in the film, by dropping water on the crack for 30 mins, the destroyed surfaces as well as the CNTs network can be brought into intimate contact due to the high inter-diffusion and flowability of PEM films. The healable transparent chemical gas sensor device specifically responded to NH3, compared to other volatile organic compounds. The repeatable healability of the sensing performance was observed.

All the devices described above are partially self-healable by the incorporation of

15



Page 16 of 57

self-healing materials into electronic devices. Recently, Haick et al. developed a complete self-healing device. Every part of this bendable and stretchable chemiresistor (i.e., substrate, electrode, and sensing layer) is self-healing.25 The self-healing chemiresistor was composed of self-healing disulfide cross-linked polyurethane (sh-crl-PU) as substrate, self-healing polyurethane/silver-microparticles (sh-µAg-PU) composite as sensing electrodes and gold nanoparticle (AuNP) film as conductor. The self-healing of the substrate and electrodes resulted from the reversible hydrogen bonding between polymer chains. Organic-capped AuNP layer intrinsically does not have self-healing properties; however, there was an “induced” healing caused by the self-healing process of the polymeric substrate lying beneath. The self-healing chemiresistor was able to sense pressure, strain and volatile organic compounds. This fully self-healable and multifunctional sensing platform provided a revolutionary improvement in self-healing sensors.

Human skin senses pressure, temperature, and other complex environmental stimuli with excellent self-healing capability. E-skin represents stretchable, flexible, and dexterous electronics, which can mimic the properties of human skin.20 As discussed in Section 3.1, Bao et al. reported the flexible and electrically conducting material with good stretchability and self-healing performance.26 The material can be mounted onto a PET substrate to form a flexion sensor. Meanwhile, a tactile sensor was made by using a parallel plate structure with the piezo-resistive composite sandwiched between the conductive composite. As shown in Figure 5c,d, the material is not only

16


Page 17 of 57 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


pressure sensitive but flexion sensitive too. The tactile and the flexion sensors were integrated onto the palm and the elbow of a mannequin, respectively, in the path of electric circuits using the light intensity of LEDs as indicators of mechanical forces (Figure 5e-g). By varying the pressures and the flexion angles of the limb, the resistance of sensors changed so as to modulate current flow through the sensor, which then changed the intensity of the LEDs. Saiz et al. confined a supramolecular polymer in a graphene ultralight network.88 The robust graphene-based composites also showed electrically conductive and self-healable properties. They were demonstrated the ability to sense pressure and flexion for E-skins, and fully restore their mechanical properties after multiple sequential damages. These systems show that for practical uses of E-skins, the materials and device components need to be stretchable, self-healable and have high performance to achieve high sensitivity and high stability of the sensors. 3.3

Supercapacitors

Supercapacitors or electrochemical capacitors are promising energy storage devices, which are attracting attentions due to the fast rate of charge-discharge, long lifetime cycle and high-power density.89 Great efforts have been devoted to develop supercapacitors with high flexibility and light weight. However, the deformation and/or breakage resulting from stretching or mechanical damage would limit the reliability and shorten the lifetime of the supercapacitors. By utilizing self-healing materials in fabricating supercapacitors is a good alternative to restore the electrical

17



Page 18 of 57

properties after mechanical damage.

Wang et al. reported the first mechanically and electrically self-healing supercapacitors in 2014.29 They fabricated the electrodes by spreading SWCNTs films onto a self-healing substrate, which was prepared by filling hierarchical TiO2 nanoflowers (~400 nm) into a Leibler-method synthesized self-healing polymer (LSHP),57 as shown in Figure 6(a, b, c). The electrical conductivity of the electrode could be restored after damage as the lateral movement of the underlying self-healing substrate enables the SWCNTs films brought into contact. The specific value of the capacitance could be restored up to 85.7% after the 5th cut. As opposed to the planar-like device mentioned above, Sun et al. established a novel wire-shaped self-healing supercapacitor based on the same self-healing polymer – LSHP, as shown in Figure 6d.28 Three conducting materials (aligned-CNT sheets, AgNWs, and CNT network) were composited with the polymer fibers. The performance of the composites recovered by 92% after the self-healing. A more efficient approach was proposed by employing the electrodes’ own magnetic force to reconnecting and re-aligning the broken wires.27 The yarn-based supercapacitor was produced by wrapping magnetic electrodes (containing Fe3O4 particles and a layer of polypyrrole) in a self-healable PU shell, as shown in Figure 6e. Up to ~72% of the specific capacitance could be recovered after going through four breaking/healing cycles. 3.4

Perovskite solar cells

The emergence of perovskite solar cells (PrSC) has changed the development of the 18


Page 19 of 57 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


3rd generation photovoltaics (PV) technology in recent years due to the novel properties of the organic-inorganic metal halide perovskites such as suitable direct bandgap, high absorption coefficient, long charge carrier diffusion length and ability to be solution processed. The highest certified power conversion efficiency (PCE) of PrSCs has exceeded 22%,90 making this new type of PV device as the revolutionary thin film solar technology.91 Despite the high PCE, more efforts are still needed to achieve the massive production of solar modules based on the PrSCs. One serious issue is the poor stability of the commonly used organic-inorganic metal halide perovskites which degrade fast when in contact with oxygen, moisture as well as ultraviolet light.31,92–96 The moisture degradation of perovskite films, such as CH3NH3PbI3 (MAPbI3), is accompanied with the transformation of MAPbI3 to MAI and metal halides.31

To prevent the moisture degradation of PrSCs, Zhao et al. reported on the incorporation of a self-healing moisture absorber, polyethylene glycol (PEG), into perovskite layers to protect them from moisture (Figure 7a).97 Performance of the device recovered after water-spraying and storing in ambient air (Figure 7b). The colour of the perovskite film with PEG changed from black to yellow after 45 s of water-spraying, but recovered to black after returning to ambient air (Figure 7c). The self-healing effect can be attributed to the excellent hygroscopicity of the PEG molecules and their strong binding effect with MAI (Figure 7d). After water-spraying, MAPbI3 decomposed into PbI2 and MAI. MAI was anchored by the nearby PEG

19



Page 20 of 57

molecules and then reacted with PbI2 to regenerate the MAPbI3 perovskite film. This self-healing effect can help to improve the stability and boost the commercialization of the perovskite PV devices. 3.5

FETs

The utility of organic FETs (OFETs) has been demonstrated in multiple electronic devices such as flexible sensors,98 memory devices,99 and in the driving circuitry of organic displays.100 There are now a bunch of OFETs with new semiconductor materials exhibiting field-effect mobilities exceeding 1 cm2V-1s-1.101–114 These OFETs are able to match or even exceed the basic performance of amorphous silicon thin-film transistors.

As OFETs are moving towards printable and flexible electronics, components of which are more susceptible to scratching, rupture, or other damage, dielectric breakdown becomes an urgent impede for the development of high performance OFETs.34–36,115,116 Dielectric breakdown is usually triggered by the exceeding gate-source voltage field, and that would dramatically suppress the performance of electric devices (such as FETs) with high current leakage. Using AlOx as dielectric, Lu and coworkers have fabricated self-healing FETs that automatically regenerate fresh oxide in the vicinity of the damaged areas after air exposure.34 Transfer characteristics of a device before and after self-healing (Figure 8a-c) show that the device properties were nearly fully restored after the repair.

For flexible electronics, excessive stress is also a reason of dielectric breakdown. One 20


Page 21 of 57 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


strategy to solve this problem is to introduce self-healing elastomers as dielectrics. Rao et al. incorporated metal−ligand as crosslinking sites in nonpolar PDMS polymers.36 The metal−ligand coordination endowed the polymer a fast self-healing ability at ambient condition. Figure 8d-g shows the stress-strain behaviour of a pristine and a healed zinc trifluoromethanesulfonate (Zn(OTf)2)-PDMS films. The healed Zn(OTf)2-PDMS films showed a 76 ± 22% of strain recovery compared to the pristine film. The healing efficiencies were not significantly affected by the surface aging effects.

4

Conclusions and Outlooks

This paper reviews the recent exciting developments in the field of self-healing polymeric materials and composites along with their potential applications for electronic devices. In general, self-healing polymeric materials can be divided into autonomous and non-autonomous self-healing. It can also be categorized based on extrinsic and intrinsic self-healing, where intrinsic self-healing polymers recover damage through physical molecular diffusion or chemical bond interaction (reversible covalent, non-covalent and intermolecular forces). Table 2 summarizes the recent self-healing materials for various devices, specifying their healing mechanisms, electrical performance and potential applications. The materials are categorized according to their applications.

Although very promising advances have been made so far, new and innovative material strategies at a system level are still needed to implement self-healing devices 21



Page 22 of 57

for practical use and eventual commercialization. We list a few of these challenges:

1) Integration of all compatible self-healing materials into single device to realize completely self-healing devices.

2) The functional properties of the existing self-healing polymers are low, limiting the eventual performance and usage in devices.

3) Stringent, non-autonomic healing conditions of materials and devices.

To address these challenges, first, we will likely need to utilize simulation and modelling at molecular levels are needed to better understand the healing phenomenon at the damage interfaces. With better understanding at the nano- to micro-scale, new materials and scalable fabrication strategies can be developed. For example, there is a need to design and synthesize self-healing polymers that have greater intrinsic conductivity, and have new functions embedded in self-healing materials, such as sensors, actuators and other opto-electronic capabilities.

It is envisaged that the future devices can repeatedly and rapidly self-heal intrinsically under a normal working environment. For example, wearable devices can fully heal upon damage at close to skin temperature and humidity, without the need to heat up the device or using toxic organic solvents. Materials that self-heal under ambient environment and conditions are especially beneficial for the development of smart, self-healable consumer devices.

As self-healing materials continue their rapid development, devices made from 22


Page 23 of 57 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


self-healing materials can eventually be functional in harsher working environments, such as deep sea or outer space, where arduous repair processes of the devices can be eliminated. The maintenance and replacement costs of equipment and device could also be reduced. Crucially, these self-healable materials have the potential to reduce electronic waste via their autonomic repair or semi-autonomic functions, and advance our connected world towards a more sustainable and perhaps space-faring future.

23


ACS Applied Materials & Interfaces 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47

Page 24 of 57

List of Tables Table 1. Self-healing conductors Year

Material

Composition

Healing mechanism

Healing condition

Performance (given in conductivity or resistance)

Performance after healing

Ref.

2007

Organometallic polymer conductor

N-heterocyclic carbenes and transition metals

Dynamic metal-carbon bond

150 °C in the presence of DMSO vapour, 2 hrs

10−3 S cm−1

Not reported

63

2015

Metal–ligand supramolecule

Polypyrrole/ supramolecular gel (PPy/G-Zn-tpy)

Noncovalent intermolecular interactions and metal–ligand bonds

R.T., solution of Zn-tpy supramolecule, 1 min

0.12 S cm−1

0.10 S cm−1

76

2012

Supramolecular organic–inorganic composite

µNi/ supramolecular composite

Hydrogen bonding

R.T., 3 min

40 S cm−1

35 S cm−1

26

24


Page 25 of 57 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47


2012

Polyelectrolyte multilayer coated with silver nanowires

silver conductive nanowires (AgNWs)/ (branched poly(ethylenimine) (bPEI)/ poly(acrylic acid)–hyaluronic acid (PAA–HA))*50 film

Hydrogen bonding

R.T. with a drop of water, 2 min

0.38 Ω sq−1

0.42 Ω sq−1

77

2017

Graphene oxide conductive hydrogel

Polydopamine-graphene oxide-polyacrymide (PDA–pGO– PAM)

Hydrogen bonding, π– π stacking and electrostatic interactions

R.T., 1 day

0.1 S cm-1

Healing efficiency of ~98%

78

2016

Graphite/polymer composite for stretchable conductors

Graphite/ bPEI

Hydrogen bonding

R.T., 10 s

1.98 S cm-1

98%

117

2013

Polymer embedded with liquid metal

Leibler-method synthesized self-healing polymer (LSHP)/ Eutectic Gallium-Indium (EGaIn)

Hydrogen bonding

R.T., ∼10 min

10–3 Ω

∼1 Ω

79

2012

Epoxy embedded with liquid metal

Epoxy embedded with gallium-indium (Ga–In) in polymeric urea-formaldehyde (UF) microcapsules

Micro-encapsulated liquid metal

R.T.

Not specified

Healing efficiency of conductance ~98%

81

2012

Conductive ink of

Polyurethane (PU)/ silver paste

Micro-encapsulated

R.T., 2 weeks

0.95 Ω

1.45 Ω

118

25



2015

2010

2017

polymer embedded with capsules of silver paste Conductive ink composites for printed electrochemical devices Core–shell microcapsules with charge-transfer salts Polar polymer with ionic liquid (salt)

Page 26 of 57

capsules

silver paste

Hexyl-acetate healing agent

Release of healing agent from a fracture capsule

R.T., few seconds

Not specified

Not specified

75

Poly(urea-formaldehyde) microcapsules of tetrathiafulvalene (TTF) and tetracyanoquinodimethane (TCNQ) PVDF-co-HFP-5545/ 1-ethyl-3-methylimidazolium trifluoromethanesulfonate (EMIOTf)

Micro-encapsulated salts

R.T.

Not specified

Not specified

80

Ion-dipole interactions

R.T., 24 h; 50 oC, 6h

10–5 S cm-1

Not reported

59

Table 2. Self-healing materials for smart devices Sensors Year

Self-healing material

Composition

Healing mechanism

Healing condition

Performance


Application

Ref.

2014

Polymer composite electrode

Polymer of furan oligomer and 1,8-bis(maleimido)-1-ethylpropane (P(FR-BME))/ AgNWs

Reversible DA cycloaddition reaction

Heating at 100 °C, 6 min

18 Ω

21 Ω

Capacitive touch screen sensors

19

26


Page 27 of 57 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47


2015

Conductive elastomers

Host–guest interactions

R.T., 5 min

Polymer dielectrics

Poly(2-hydroxyethyl methacrylate) (PHEMA)-SWCNT-β- cyclodextrin (β-CD) N-(2-hydroxypropyl)methacrylamide (PHPMA) / polyethylenimine (PEI)

2015

Hydrogen bonding

R.T., ∼10 h

2015

Conductive polymer composites

Reduced graphene oxide (rGO) / polybutylene succinate (PBS) composite

R.T., ∼10 min

2015

Supramolecular network with ionic liquid Nanoparticles in polymer matrix

[OMIm][PF6]/ supramolecular

Dynamic dative bonds between boron and the oxygen in the Si-O groups Hydrogen bonding

2015

2016

Electrodeposited gelatin electrodes

2016

Fully self-healing chemiresistor

Embed surface modified CCTO nanoparticles (S-CCTO) in Diels– Alder (DA) cycloaddition polymeric (MT) matrix (MT/S-CCTO) GOx/gelation

Self-healing disulfide-cross-linked polyurethane (sh-crl-PU)/ gold nanoparticle (AuNP) film/ sh-µAuNP

Reversible DA adducts

Reversible bonding between gelatin and GOx/gelatin Hydrogen and reversible covalent

0.75~7.76 S m-1

94.6%~ 96.8%

Humidity sensor

87

35

~80%

OFETs/ Chemical sensor Flexion sensor

Heating at 50 °C, 5 min Heating at 105 °C, 30 min

Circuit/electric sensor/NIR sensor Motion sensor

84

Clamped together, refrigerated at 22 °C, 10 min R.T., 30 min

Biosensor

119

Chemiresistor for pressure/strain,

25

64 S m−1

20 Ω

400 Ω

88

23

27



Page 28 of 57

volatile organic compounds (VOCs), and temperature sensors

disulfide bonding of substrate and electrode, and “induced” self-healing of AuNP film Supercapacitors Year Self-healing material

Composition

Healing mechanism

2014

Conducting polymer wires

Carbon nanotube (CNT)/AgNWsLSHP fiber

2014

Supramolecular network with inorganic spheres for substrates

TiO2/ LSHP composite

2015

Polymer shell wrapping

Stainless bare yarn/ Fe3O4/ polypyrrole (PPy) / PU

Hydrogen bonding and “induced” self-healing of CNT film by van der Waals forces Hydrogen bonding for substrate and “induced” self-healing of CNT film Hydrogen bonding

Healing condition

Performance Performance after healing

Application

Ref.

140 F g−1

92%

Wire-shaped supercapacitors

28

Heating at 50 °C, 5 min

35.6 F g−1

34 F g−1

Supercapacitor

29

R.T., a gentle

61.4 F cm−1

71.8% after the 4th

Supercapacitor

27

28


Page 29 of 57 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47


magnetic electrodes

pressure, ~5 min

healing

Perovskite solar cell Year

Self-healing material

Composition

Healing mechanism

Healing condition

Performance


Application

Ref.

2016

Perovskite polymer-scaffold

Perovskite/ polyethylene glycol (PEG)

R.T., 45 s

~16%

Almost completely recovered

Perovskite solar cell

97

2015

Polymer sealant

Coumarin-functionalized tri-arm polyisobutylene (PIB)

Humid absorption of PEG Photo-assisted reversibly cross-linked reaction

Coating for photovoltaic devices

120

Self-healing material Gate dielectrics

Composition AlOx

Healing mechanism Oxidation

Ionic liquid dielectrics

1-ethyl-3-methylimidazolium tetracyanoborate ([EMIM][TCB]) and tannic acid

Reversible electrochemical reaction

UVC (λmax = 254 nm) and UVA (λmax = 365 nm) irradiation, 30 min

FETs Year 2012

2015

Healing condition R.T., ∼6 h or electrical annealing

Performance


Application

Ref.

FETs

34

FETs

121

29



2016

Polymeric dielectrics

2,2′-Bipyridine-terminated poly(dimethylsiloxane)s (bpyPDMS)/ (Fe2+ or Zn2+)

Metal−ligand coordination bonding

2016

Polymeric dielectrics

Amide-functionalized boron nitride nanosheets (BNNSs-CONH2)/ supramolecular nanocomposites

Hydrogen bonding

R.T., 2 days; or heating at 90 °C, a few hours R.T., ∼10 min (Or heating)

Page 30 of 57

OFETs

36

Flexible electronics and energy devices

122

30


Page 31 of 57 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


List of figures: Moisture

Self-healing

Perovskite Solar Cells

Supercapacitors

Heal

Cut

OFETs

Cut

Heal

Conductors

Batteries

E-skins Cut

Heal

Sensors Figure 1. Present electronic applications that involve self-healing materials. Reprinted in part with permission from ref. 26 Copyright 2012 Nature Publishing Group, ref. 34 Copyright 2012 American Chemical Society, ref.

37

Copyright 2013 Nature Publishing Group, ref.

Copyright 2014 American Chemical Society, ref.

29

Copyright 2014 WILEY-VCH and ref.

19

97

Copyright 2016 Nature Publishing Group.

31



Page 32 of 57

Figure 2. Examples of (a, b) capsule-based, (c, d) vascular, and (e, f) intrinsic self-healing materials. (a) Schematics of microencapsulated healing agent embed in composite matrix. (b) SEM image showing the fracture plane of a ruptured urea-formaldehyde microcapsule in a thermoset polymer matrix. Reprinted in part with permission from ref.

41

Copyright 2001

Nature Publishing Group. (c) Schematics of microvascular substrates and brittle epoxy coating containing embedded catalyst for self-healing. (d) Photograph of a self-healing substrate, showing the presence of excess healable fluid on the cracked coating surface. Reprinted in part with permission from ref.

49

Copyright 2007 Nature Publishing Group. (e)

Healing upon contact of an intrinsically self-healable polymer. (f) Optical microscope images of a damaged sample after different healing times at room temperature. Reprinted in part with permission from ref. 59 Copyright 2017 WILEY-VCH.

32


Page 33 of 57

Reversible bond incorporate to Conductive polymer a Electrically conductive material Crack

Polymerization

Resistance increase Voltage biased High resistance Heat generated Self-heal

Crack

Self-heal

Multifunctional monomer Polymer network

b Stimuli

Conductive materials incorporate to Self-healing polymer c

d Nanostructured ∝Ni Smooth spherical Ni particles Percolation theory fit

Conductivity (S/cm)

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


Nanostructured ∝Ni particle

e

Ni volume fraction

f

1 mm

Damaged

Self-healed

Figure 3. Most common approaches to self-healing conductors: (a,b) synthesized by adding reversible bonds to conductive polymer; (c-f) developed by incorporating conductive fillers to self-healing polymers. (a) Schematics illustrating the operation of an electrically conductive, self-healing material that heals upon heating. (b) A self-healable conductive polymer with dynamic equilibrium between a monomer species and an organometallic polymer that can be controlled through an external stimulus. Reprinted in part with permission from ref.

63

33



Page 34 of 57

Copyright 2007 The Royal Society of Chemistry. (c) Preparation of a self-healing composite by mixing supramolecular polymer and µNi particle. (d) Graph showing the volumetric electrical conductivity of the composite vary with the µNi particle concentration. (e) Photographs demonstrating the self-healing process of a conductive composite. 1, pristine conductor; 2, completely cut conductor (became open circuit); 3, electrical healing after putting back the materials; 4, self-healed film being flexed to illustrate mechanical healing after 5 min of self-healing at room temperature. (f) Optical microscope images showing a damaged sample and followed by the complete scar healing of the composite materials. Reprinted in part with permission from ref. 26 Copyright 2012 Nature Publishing Group.

Figure 4. (a) Time profiles of self-healing on an AgNWs/(bPEI/PAA–HA)*50 film connected in a circuit with a LED bulb. a1) Pristine film; a2) cut film; a3–a5) healing of the conductivity by dropping deionized water on the cut; a6) removing of water after self-healing process. The arrows indicate the cuts. (b-c) Schematics and SEM images of water-enabled electrical 34


Page 35 of 57 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


conductivity self-healing of an AgNWs/(bPEI/PAA–HA)*50 film. Reprinted in part with permission from ref.

77

Copyright 2012 WILEY-VCH. (d) Schematic and photograph

representations of the disconnection and reconnection of a circuit using a self-healable wire. The EGaIn channel has to be aligned when connecting the two cut surface of the wire to restore its electrical conductivity. Reprinted in part with permission from ref.

79

Copyright

2013 WILEY-VCH.

35



a

b

c

e

Page 36 of 57

d

f

g

Figure 5. Self-healing sensors. (a-b) Schematics demonstrating the fabrication of a conductive film that is healable via DA cycloaddition reaction. (a) Demonstration of two

36


Page 37 of 57 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


capacitive sensing films, which were overlaid on a LED display with conductive AgNW network on the upper surface of all the sensing films. (b) Illustration of self-healing of the touch screen. Photograph on the left showing a “smiley face” was drawn on the touch screen; middle photograph illustrating only one-half of the “smiley face” can be drawn after cutting (on the red line); after healing at 80 °C for 30 s, the whole “smiley face” can be drawn as shown in the right photograph. Reprinted in part with permission from ref. 19 Copyright 2014 American Chemical Society. (c-g) A self-healing electronic sensor skin fabricated from the self-healing conductor based on supramolecular polymer and µNi particles. (c) Electrical response of a flexion sensor in the free-standing and the self-adhered modes on PET substrates. (d) Graph showing the tactile sensor’s response when increasing the peak pressure values. (e) Photograph and circuit schematic showing a self-healing flexion and tactile sensor attached on a wooden mannequin. A flexion sensor was fixed on the inner elbow, while a tactile sensor was secured on the palm of the mannequin. LEDs mounted at the centre of body and the eye region transduce the mechanical deformation into visible outputs. (f) Demonstration of a flexion sensor circuit: LED “eyes” light up when the elbow is bent. (g) Demonstration of a tactile sensor circuit: Intensity of LED (at the centre of the body) increased with the increasing tactile pressure. Reprinted in part with permission from ref.

26

Copyright 2012 Nature Publishing Group.

37



Page 38 of 57

Figure 6. Self-healing supercapacitor. (a) The fabrication process flow of an electrically and mechanically self-healable, flexible supercapacitor. The composite consists of the flower-like TiO2 spheres and a supramolecular network that heals with hydrogen bonds. SWCNT films were deposited on these self-healing substrates, and then assembled to form the sandwiched supercapacitors. Photographs showing (b) the flexible self-healable substrate on a PET sheet after depositing the SWCNT film and (c) the self-healing supercapacitor. Reprinted in part with permission from ref.

29

Copyright 2014 WILEY-VCH. (d) Schematic illustration of the

self-healing of the conducting wire. Reprinted in part with permission from ref.

28

Copyright

2014 WILEY-VCH. (e) Fabrication process flow of a magnetic-assisted self-healing supercapacitor. The Fe3O4 nanoparticles were attached onto the yarn surface using a microwave-assisted hydrothermal method. PPy layer is electrodeposited on the annealed yarn 38


Page 39 of 57 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


to achieve a better electrochemical performance. The self-healing supercapacitor was formed by assembling the two yarns with a solid electrolyte and a self-healing shell. Reconnection of the fibers in broken yarn electrodes can be made by magnetic alignment. Reprinted in part with permission from ref. 27 Copyright 2015 American Chemical Society.

Figure 7. Self-healing perovskite film. (a) Schematic illustrating the manufacturing process of a self-healing perovskite film with PEG scaffold. (b) J-V curves of PrSCs before and after water spraying, and self-healed perovskite film. (c) Optimal images of the perovskite films with and without PEG after exposing to water-spraying for 60 s and then kept in ambient air for 60 s. The sample with PEG healed from the damage. (d) Schematic showing the self-healing mechanism, i.e. the hydrogen bond formation between the PEG molecules and the MAPbI3. Reproduced with permission from ref.

97

Copyright 2016 Nature Publishing

Group.

39



Page 40 of 57

Figure 8. Self-healing OFETs. (a-c) Curves of IGS-VGS and IDS-VGS of a graphene FET on PET and self-healing test for metal−ligand PDMS polymer. (a) Before and (b) after the AlOx dielectric breakdown. Schematic shows the native AlOx regrown at the site of breakdown. (c) The AlOx layer self-healed after aging in air for 6 h. Reprinted in part with permission from ref.

34

Copyright 2012 American Chemical Society. (d) Mechanical self-healing of a

Zn(OTf)2-PDMS polymer at ambient environment. (e, f) Photographs showing the self-healed Zn(OTf)2-PDMS polymer film when tested under tensile stress with >250% strain. (e)

40


Page 41 of 57 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


Material was cut and self-healed (red box). (f) Material was ruptured with tensile stress, then the ruptured surface was placed back for self-healing. (g) Graph showing the self-healing efficiencies at ambient environment of all the studied materials. Reprinted in part with permission from ref. 36 Copyright 2016 American Chemical Society.

Acknowledgements

We acknowledge support of the National University of Singapore (NUS) Start-up Grant, National Research Foundation (NRF) Singapore, and from the MOE Key Laboratory of Macromolecular Synthesis and Functionalization, Zhejiang University (2015MSF03).

41



Page 42 of 57

References (1)

Martin, P. Wound Healing--Aiming for Perfect Skin Regeneration. Science 1997, 276 (5309), 75–81.

(2)

Outwater, J. O.; Gerry, D. J. On the Fracture Energy, Rehealing Velocity and Refracture Energy of Cast Epoxy Resin. J. Adhes. 1969, 1 (4), 290–298.

(3)

Jud, K.; Kausch, H. H.; Williams, J. G. Fracture Mechanics Studies of Crack Healing and Welding of Polymers. J. Mater. Sci. 1981, 16 (1), 204–210.

(4)

Wu, D. Y.; Meure, S.; Solomon, D. Self-Healing Polymeric Materials: A Review of Recent Developments. Prog. Polym. Sci. 2008, 33 (5), 479–522.

(5)

Zwaag, S. Self Healing Materials: An Alternative Approach to 20 Centuries of

Materials Science; Springer Science+ Business Media BV, 2008. (6)

Ghosh, S. K. Self-Healing Materials: Fundamentals, Design Strategies, and

Applications; John Wiley & Sons, 2009. (7)

Hager, M. D.; Greil, P.; Leyens, C.; van der Zwaag, S.; Schubert, U. S. Self-Healing Materials. Adv. Mater. 2010, 22 (47), 5424–5430.

(8)

Yang, Y.; Urban, M. W. Self-Healing Polymeric Materials. Chem. Soc. Rev. 2013.

(9)

Huynh, T.-P.; Sonar, P.; Haick, H. Advanced Materials for Use in Soft Self-Healing Devices. Adv. Mater. 2017, 29 (19), 1604973.

(10)

Luo, C. S.; Wan, P.; Yang, H.; Shah, S. A. A.; Chen, X. Healable Transparent Electronic Devices. Adv. Funct. Mater. 2017, 27 (23), 1606339.

(11)

Forrest, S. R. The Path to Ubiquitous and Low-Cost Organic Electronic Appliances on Plastic. Nature 2004, 428 (6986), 911–918. 42


Page 43 of 57 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


(12)

Lipomi, D. J.; Bao, Z. Stretchable and Ultraflexible Organic Electronics. MRS Bull. 2017, 42 (2), 93–97.

(13)

Tee, B. C. K.; Mannsfeld, S. C. B.; Bao, Z. Elastomer-Based Pressure and Strain Sensors. In Stretchable Electronics; Wiley-VCH Verlag GmbH & Co. KGaA: Weinheim, Germany, 2012; pp 325–353.

(14)

Benight, S. J.; Wang, C.; Tok, J. B. H.; Bao, Z. Stretchable and Self-Healing Polymers and Devices for Electronic Skin. Prog. Polym. Sci. 2013, 38 (12), 1961–1977.

(15)

Hammock, M. L.; Chortos, A.; Tee, B. C. ‐K.; Tok, J. B. ‐H.; Bao, Z. 25th Anniversary Article: The Evolution of Electronic Skin (E‐Skin): A Brief History, Design Considerations, and Recent Progress. Adv. Mater. 2013, 25 (42), 5997–6038.

(16)

Wu, M.; Johannesson, B.; Geiker, M. A Review: Self-Healing in Cementitious Materials and Engineered Cementitious Composite as a Self-Healing Material. Constr.

Build. Mater. 2012, 28 (1), 571–583. (17)

Van Tittelboom, K.; De Belie, N. Self-Healing in Cementitious Materials—A Review.

Materials (Basel). 2013, 6 (6), 2182–2217. (18)

Hautakangas, S.; Schut, H.; van Dijk, N. H.; Rivera Díaz del Castillo, P. E. J.; van der Zwaag, S. Self-Healing of Deformation Damage in Underaged Al–Cu–Mg Alloys. Scr.

Mater. 2008, 58 (9), 719–722. (19)

Li, J.; Liang, J.; Li, L.; Ren, F.; Hu, W.; Li, J.; Qi, S.; Pei, Q. Healable Capacitive Touch Screen Sensors Based on Transparent Composite Electrodes Comprising Silver Nanowires and a Furan/Maleimide Diels–Alder Cycloaddition Polymer. ACS Nano 2014, 8 (12), 12874–12882. 43



(20)

Page 44 of 57

Bai, S.; Sun, C.; Yan, H.; Sun, X.; Zhang, H.; Luo, L.; Lei, X.; Wan, P.; Chen, X. Healable, Transparent, Room-Temperature Electronic Sensors Based on Carbon Nanotube Network-Coated Polyelectrolyte Multilayers. Small 2015, 11 (43), 5807– 5813.

(21)

D’Elia, E.; Barg, S.; Ni, N.; Rocha, V. G.; Saiz, E. Self-Healing Graphene-Based Composites with Sensing Capabilities. Adv. Mater. 2015, 27 (32), 4788–4794.

(22)

He, Y.; Liao, S.; Jia, H.; Cao, Y.; Wang, Z.; Wang, Y. A Self-Healing Electronic Sensor Based on Thermal-Sensitive Fluids. Adv. Mater. 2015, 27 (31), 4622–4627.

(23)

Yang, Y.; Zhu, B.; Yin, D.; Wei, J.; Wang, Z.; Xiong, R.; Shi, J.; Liu, Z.; Lei, Q. Flexible Self-Healing Nanocomposites for Recoverable Motion Sensor. Nano Energy 2015, 17, 1–9.

(24)

Jin, H.; Huynh, T.-P.; Haick, H. Self-Healable Sensors Based Nanoparticles for Detecting Physiological Markers via Skin and Breath: Toward Disease Prevention via Wearable Devices. Nano Lett. 2016, 16 (7), 4194–4202.

(25)

Huynh, T.-P.; Haick, H. Self-Healing, Fully Functional, and Multiparametric Flexible Sensing Platform. Adv. Mater. 2016, 28 (1), 138–143.

(26)

Tee, B. C.-K.; Wang, C.; Allen, R.; Bao, Z. An Electrically and Mechanically Self-Healing Composite with Pressure- and Flexion-Sensitive Properties for Electronic Skin Applications. Nat. Nanotechnol. 2012, 7 (12), 825–832.

(27)

Huang, Y.; Huang, Y.; Zhu, M.; Meng, W.; Pei, Z.; Liu, C.; Hu, H.; Zhi, C. Magnetic-Assisted, Self-Healable, Yarn-Based Supercapacitor. ACS Nano 2015, 9 (6), 6242–6251. 44


Page 45 of 57 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


(28)

Sun, H.; You, X.; Jiang, Y.; Guan, G.; Fang, X.; Deng, J.; Chen, P.; Luo, Y.; Peng, H. Self-Healable Electrically Conducting Wires for Wearable Microelectronics. Angew.

Chemie Int. Ed. 2014, 53 (36), 9526–9531. (29)

Wang, H.; Zhu, B.; Jiang, W.; Yang, Y.; Leow, W. R.; Wang, H.; Chen, X. A Mechanically and Electrically Self-Healing Supercapacitor. Adv. Mater. 2014, 26 (22), 3638–3643.

(30)

Li, X.; Yu, D.; Cao, F.; Gu, Y.; Wei, Y.; Wu, Y.; Song, J.; Zeng, H. Healing All-Inorganic Perovskite Films via Recyclable Dissolution–Recyrstallization for Compact and Smooth Carrier Channels of Optoelectronic Devices with High Stability.

Adv. Funct. Mater. 2016, 26 (32), 5903–5912. (31)

Wang, D.; Wright, M.; Elumalai, N. K.; Uddin, A. Stability of Perovskite Solar Cells.

Sol. Energy Mater. Sol. Cells 2016, 147, 255–275. (32)

Zhao, Y.; Wei, J.; Li, H.; Yan, Y.; Zhou, W.; Yu, D.; Zhao, Q. A Polymer Scaffold for Self-Healing Perovskite Solar Cells. 2016, 7, 10228.

(33)

Lang, F.; Nickel, N. H.; Bundesmann, J.; Seidel, S.; Denker, A.; Albrecht, S.; Brus, V. V; Rappich, J.; Rech, B.; Landi, G.; et al. Radiation Hardness and Self-Healing of Perovskite Solar Cells. Adv. Mater. 2016, 28 (39), 8726–8731.

(34)

Lu, C.-C.; Lin, Y.-C.; Yeh, C.-H.; Huang, J.-C.; Chiu, P.-W. High Mobility Flexible Graphene Field-Effect Transistors with Self-Healing Gate Dielectrics. ACS Nano 2012,

6 (5), 4469–4474. (35)

Huang, W.; Besar, K.; Zhang, Y.; Yang, S.; Wiedman, G.; Liu, Y.; Guo, W.; Song, J.; Hemker, K.; Hristova, K.; et al. A High-Capacitance Salt-Free Dielectric for 45



Page 46 of 57

Self-Healable, Printable, and Flexible Organic Field Effect Transistors and Chemical Sensor. Adv. Funct. Mater. 2015, 25 (24), 3745–3755. (36)

Rao, Y.-L.; Chortos, A.; Pfattner, R.; Lissel, F.; Chiu, Y.-C.; Feig, V.; Xu, J.; Kurosawa, T.; Gu, X.; Wang, C.; et al. Stretchable Self-Healing Polymeric Dielectrics Cross-Linked Through Metal–Ligand Coordination. J. Am. Chem. Soc. 2016, 138 (18), 6020–6027.

(37)

Wang, C.; Wu, H.; Chen, Z.; McDowell, M. T.; Cui, Y.; Bao, Z. Self-Healing Chemistry Enables the Stable Operation of Silicon Microparticle Anodes for High-Energy Lithium-Ion Batteries. Nat. Chem. 2013, 5 (12), 1042–1048.

(38) Sun, Y.; Lopez, J.; Lee, H. W.; Liu, N.; Zheng, G.; Wu, C. L.; Sun, J.; Liu, W.; Chung, J. W.; Bao, Z.; et al. A Stretchable Graphitic carbon/Si Anode Enabled by Conformal Coating of a Self-Healing Elastic Polymer. In Materials Engineering and Sciences

Division 2016 - Core Programming Area at the 2016 AIChE Annual Meeting; 2016; Vol. 2, pp 532–538. (39)

Tee, B. C. K.; Wang, C.; Allen, R.; Bao, Z. An Electrically and Mechanically Self-Healing Composite with Pressure- and Flexion-Sensitive Properties for Electronic Skin Applications. Nat Nano 2012, 7 (12), 825–832.

(40)

Blaiszik, B. J.; Kramer, S. L. B.; Olugebefola, S. C.; Moore, J. S.; Sottos, N. R.; White, S. R. Self-Healing Polymers and Composites. Annu. Rev. Mater. Res. 2010, 40 (1), 179–211.

(41)

White, S. R.; Sottos, N. R.; Geubelle, P. H.; Moore, J. S.; Kessler, M. R.; Sriram, S. R.; Brown, E. N.; Viswanathan, S. Autonomic Healing of Polymer Composites. Nature 46


Page 47 of 57 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


2001, 409 (6822), 794–797. (42)

Brown, E. N.; Kessler, M. R.; Sottos, N. R.; White, S. R. In Situ Poly(urea-Formaldehyde) Microencapsulation of Dicyclopentadiene. J. Microencapsul. 2003, 20 (6), 719–730.

(43)

Yeom, C. K.; Oh, S. B.; Rhim, J. W.; Lee, J. M. Microencapsulation of Water-Soluble Herbicide by Interfacial Reaction. I. Characterization of Microencapsulation. J. Appl.

Polym. Sci. 2000, 78 (9), 1645–1655. (44)

Rule, J. D.; Brown, E. N.; Sottos, N. R.; White, S. R.; Moore, J. S. Wax-Protected Catalyst Microspheres for Efficient Self-Healing Materials. Adv. Mater. 2005, 17 (2), 205–208.

(45)

Yang, J.; Keller, M. W.; Moore, J. S.; White, S. R.; Sottos, N. R. Microencapsulation of Isocyanates for Self-Healing Polymers. Macromolecules 2008, 41 (24), 9650–9655.

(46)

Suryanarayana, C.; Rao, K. C.; Kumar, D. Preparation and Characterization of Microcapsules Containing Linseed Oil and Its Use in Self-Healing Coatings. Prog. Org.

Coatings 2008, 63 (1), 72–78. (47)

Keller, M. W.; White, S. R.; Sottos, N. R. A Self-Healing Poly(Dimethyl Siloxane) Elastomer. Adv. Funct. Mater. 2007, 17 (14), 2399–2404.

(48)

Jin, H.; Mangun, C. L.; Stradley, D. S.; Moore, J. S.; Sottos, N. R.; White, S. R. Self-Healing Thermoset Using Encapsulated Epoxy-Amine Healing Chemistry.

Polymer (Guildf). 2012, 53 (2), 581–587. (49)

Toohey, K. S.; Sottos, N. R.; Lewis, J. A.; Moore, J. S.; White, S. R. Self-Healing Materials with Microvascular Networks. Nat. Mater. 2007, 6 (8), 581–585. 47



(50)

Page 48 of 57

Hansen, C. J.; Wu, W.; Toohey, K. S.; Sottos, N. R.; White, S. R.; Lewis, J. A. Self-Healing Materials with Interpenetrating Microvascular Networks. Adv. Mater. 2009, 21 (41), 4143–4147.

(51)

Williams, H. R.; Trask, R. S.; Knights, A. C.; Williams, E. R.; Bond, I. P. Biomimetic Reliability Strategies for Self-Healing Vascular Networks in Engineering Materials. J.

R. Soc. Interface 2008, 5 (24), 735–747. (52)

Murphy, E. B.; Bolanos, E.; Schaffner-Hamann, C.; Wudl, F.; Nutt, S. R.; Auad, M. L. Synthesis and Characterization of a Single-Component Thermally Remendable Polymer Network: Staudinger and Stille Revisited. Macromolecules 2008, 41 (14), 5203–5209.

(53)

Chen, X.; Dam, M. A.; Ono, K.; Mal, A.; Shen, H.; Nutt, S. R.; Sheran, K.; Wudl, F. A Thermally Re-Mendable Cross-Linked Polymeric Material. Science 2002, 295 (5560), 1698–1702.

(54)

Zhang, Z. P.; Rong, M. Z.; Zhang, M. Q. Mechanically Robust, Self-Healable, and Highly Stretchable “Living” Crosslinked Polyurethane Based on a Reversible C‐C Bond. Adv. Funct. Mater. 2018, 1706050.

(55)

Zhang, M.; Xu, D.; Yan, X.; Chen, J.; Dong, S.; Zheng, B.; Huang, F. Self-Healing Supramolecular Gels Formed by Crown Ether Based Host-Guest Interactions. Angew.

Chemie 2012, 124 (28), 7117–7121. (56)

Kakuta, T.; Takashima, Y.; Nakahata, M.; Otsubo, M.; Yamaguchi, H.; Harada, A. Preorganized Hydrogel: Self-Healing Properties of Supramolecular Hydrogels Formed by Polymerization of Host-Guest-Monomers That Contain Cyclodextrins and 48


Page 49 of 57 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


Hydrophobic Guest Groups. Adv. Mater. 2013, 25 (20), 2849–2853. (57)

Cordier, P.; Tournilhac, F.; Soulié-Ziakovic, C.; Leibler, L. Self-Healing and Thermoreversible Rubber from Supramolecular Assembly. Nature 2008.

(58)

Yanagisawa, Y.; Nan, Y.; Okuro, K.; Aida, T. Mechanically Robust, Readily Repairable Polymers via Tailored Noncovalent Cross-Linking. Science 2017, eaam7588.

(59) Cao, Y.; Morrissey, T. G.; Acome, E.; Allec, S. I.; Wong, B. M.; Keplinger, C.; Wang, C. A Transparent, Self-Healing, Highly Stretchable Ionic Conductor. Adv. Mater. 2017, 29 (10), 1605099. (60)

Wool, R. P. Self-Healing Materials: A Review. Soft Matter 2008, 4 (3), 400.

(61)

Wu, D. Y.; Meure, S.; Solomon, D. Self-Healing Polymeric Materials: A Review of Recent Developments. Prog. Polym. Sci. 2008, 33 (5), 479–522.

(62)

Murphy, E. B.; Wudl, F. The World of Smart Healable Materials. Progress in Polymer

Science (Oxford). 2010, pp 223–251. (63)

Williams, K. A.; Boydston, A. J.; Bielawski, C. W. Towards Electrically Conductive, Self-Healing Materials. J. R. Soc. Interface 2007, 4 (13), 359–362.

(64)

Kirkby, E. L.; Rule, J. D.; Michaud, V. J.; Sottos, N. R.; White, S. R.; Månson, J.-A. E. Embedded Shape-Memory Alloy Wires for Improved Performance of Self-Healing Polymers. Adv. Funct. Mater. 2008, 18 (15), 2253–2260.

(65)

Duenas, T.; Bolanos, E.; Murphy, E.; Mal, A.; Wudl, F.; Schaffner, C.; Wang, Y.; Hahn, H. T.; Ooi, T. K.; Jha, A. Multifunctional Self-Healing and Morphing Composites. 2006.

(66)

Kalista, S. J.; Ward, T. C.; Oyetunji, Z. Self-Healing of Poly(Ethylene-Co-Methacrylic 49



Page 50 of 57

Acid) Copolymers Following Projectile Puncture. Mech. Adv. Mater. Struct. 2007, 14 (5), 391–397. (67)

John Varley, R.; van der Zwaag, S. Development of a Quasi-Static Test Method to Investigate the Origin of Self-Healing in Ionomers under Ballistic Conditions. Polym.

Test. 2008, 27 (1), 11–19. (68)

Burnworth, M.; Tang, L.; Kumpfer, J. R.; Duncan, A. J.; Beyer, F. L.; Fiore, G. L.; Rowan, S. J.; Weder, C. Optically Healable Supramolecular Polymers. Nature 2011,

472 (7343), 334–337. (69)

Fiore, G. L.; Rowan, S. J.; Weder, C. Optically Healable Polymers. Chem. Soc. Rev. 2013, 42 (17), 7278.

(70)

Taylor, D. L.; in het Panhuis, M. Self-Healing Hydrogels. Adv. Mater. 2016, 28 (41), 9060–9093.

(71)

Hunt, S.; McKay, T. G.; Anderson, I. A. A Self-Healing Dielectric Elastomer Actuator.

Appl. Phys. Lett. 2014, 104 (11), 113701. (72)

Li, C.-H.; Wang, C.; Keplinger, C.; Zuo, J.-L.; Jin, L.; Sun, Y.; Zheng, P.; Cao, Y.; Lissel, F.; Linder, C.; et al. A Highly Stretchable Autonomous Self-Healing Elastomer.

Nat. Chem. 2016, 8 (6), 618–624. (73)

Yuan, W.; Hu, L.; Yu, Z.; Lam, T.; Biggs, J.; Ha, S. M.; Xi, D.; Chen, B.; Senesky, M. K.; Grüner, G.; et al. Fault-Tolerant Dielectric Elastomer Actuators Using Single-Walled Carbon Nanotube Electrodes. Adv. Mater. 2008, 20 (3), 621–625.

(74)

Bandodkar, A. J.; Lopez, C. S.; Mohan, A. M. V.; Yin, L.; Kumar, R.; Wang, J. All-Printed Magnetically Self-Healing Electrochemical Devices. Sci. Adv. 2016, 2 (11), 50


Page 51 of 57 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


e1601465--e1601465. (75)

Bandodkar, A. J.; Mohan, V.; López, C. S.; Ramírez, J.; Wang, J. Self-Healing Inks for Autonomous Repair of Printable Electrochemical Devices. Adv. Electron. Mater. 2015,

1 (12), 1500289. (76)

Shi, Y.; Wang, M.; Ma, C.; Wang, Y.; Li, X.; Yu, G. A Conductive Self-Healing Hybrid Gel Enabled by Metal–Ligand Supramolecule and Nanostructured Conductive Polymer.

Nano Lett. 2015, 15 (9), 6276–6281. (77)

Li, Y.; Chen, S.; Wu, M.; Sun, J. Polyelectrolyte Multilayers Impart Healability to Highly Electrically Conductive Films. Adv. Mater. 2012, 24 (33), 4578–4582.

(78)

Han, L.; Lu, X.; Wang, M.; Gan, D.; Deng, W.; Wang, K.; Fang, L.; Liu, K.; Chan, C. W.; Tang, Y.; et al. A Mussel-Inspired Conductive, Self-Adhesive, and Self-Healable Tough Hydrogel as Cell Stimulators and Implantable Bioelectronics. Small 2017, 13 (2), 1601916.

(79)

Palleau, E.; Reece, S.; Desai, S. C.; Smith, M. E.; Dickey, M. D. Self‐Healing Stretchable Wires for Reconfigurable Circuit Wiring and 3D Microfluidics. Adv. Mater. 2013, 25 (11), 1589–1592.

(80)

Odom, S. A.; Caruso, M. M.; Finke, A. D.; Prokup, A. M.; Ritchey, J. A.; Leonard, J. H.; White, S. R.; Sottos, N. R.; Moore, J. S. Restoration of Conductivity with TTF-TCNQ Charge-Transfer Salts. Adv. Funct. Mater. 2010, 20 (11), 1721–1727.

(81)

Blaiszik, B. J.; Kramer, S. L. B.; Grady, M. E.; McIlroy, D. A.; Moore, J. S.; Sottos, N. R.; White, S. R. Autonomic Restoration of Electrical Conductivity. Adv. Mater. 2012,

24 (3), 398–401. 51



(82)

Page 52 of 57

Noda, A.; Hayamizu, K.; Watanabe, M. Pulsed-Gradient Spin−Echo 1 H and 19 F NMR

Ionic

Diffusion

Coefficient,

Viscosity,

and

Ionic

Conductivity

of

Non-Chloroaluminate Room-Temperature Ionic Liquids. J. Phys. Chem. B 2001, 105 (20), 4603–4610. (83)

Hapiot, P.; Lagrost, C. Electrochemical Reactivity in Room-Temperature Ionic Liquids.

Chem. Rev. 2008, 108 (7), 2238–2264. (84)

He, Y.; Liao, S.; Jia, H.; Cao, Y.; Wang, Z.; Wang, Y. A Self-Healing Electronic Sensor Based on Thermal-Sensitive Fluids. Adv. Mater. 2015, 27 (31), 4622–4627.

(85)

Chen, T.; Wang, S.; Yang, Z.; Feng, Q.; Sun, X.; Li, L.; Wang, Z.-S.; Peng, H. Flexible, Light-Weight, Ultrastrong, and Semiconductive Carbon Nanotube Fibers for a Highly Efficient Solar Cell. Angew. Chemie Int. Ed. 2011, 50 (8), 1815–1819.

(86)

Sun, H.; You, X.; Deng, J.; Chen, X.; Yang, Z.; Chen, P.; Fang, X.; Peng, H. A Twisted Wire-Shaped Dual-Function Energy Device for Photoelectric Conversion and Electrochemical Storage. Angew. Chemie - Int. Ed. 2014, 53 (26), 6664–6668.

(87)

Guo, K.; Zhang, D. L.; Zhang, X. M.; Zhang, J.; Ding, L. S.; Li, B. J.; Zhang, S. Conductive Elastomers with Autonomic Self-Healing Properties. Angew. Chemie - Int.

Ed. 2015, 54 (41), 12127–12133. (88)

D’Elia, E.; Barg, S.; Ni, N.; Rocha, V. G.; Saiz, E. Self-Healing Graphene-Based Composites with Sensing Capabilities. Adv. Mater. 2015, 27 (32), 4788–4794.

(89)

Simon, P.; Gogotsi, Y. Materials for Electrochemical Capacitors. Nat. Mater. 2008.

(90)

Yang, W. S.; Park, B.-W.; Jung, E. H.; Jeon, N. J.; Kim, Y. C.; Lee, D. U.; Shin, S. S.; Seo,

J.;

Kim,

E.

K.;

Noh,

J.

H.;

et

al.

Iodide

Management

in 52


Page 53 of 57 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


Formamidinium-Lead-Halide-Based Perovskite Layers for Efficient Solar Cells.

Science 2017, 356 (6345), 1376–1379. (91)

Manser, J. S.; Christians, J. A.; Kamat, P. V. Intriguing Optoelectronic Properties of Metal Halide Perovskites. Chem. Rev. 2016, 116 (21), 12956–13008.

(92)

Thompson, C. V. Solid-State Dewetting of Thin Films. Annu. Rev. Mater. Res. 2012, 42 (1), 399–434.

(93)

Eperon, G. E.; Burlakov, V. M.; Docampo, P.; Goriely, A.; Snaith, H. J. Morphological Control for High Performance, Solution-Processed Planar Heterojunction Perovskite Solar Cells. Adv. Funct. Mater. 2014, 24 (1), 151–157.

(94)

Eperon, G. E.; Habisreutinger, S. N.; Leijtens, T.; Bruijnaers, B. J.; van Franeker, J. J.; deQuilettes, D. W.; Pathak, S.; Sutton, R. J.; Grancini, G.; Ginger, D. S.; et al. The Importance of Moisture in Hybrid Lead Halide Perovskite Thin Film Fabrication. ACS

Nano 2015, 9 (9), 9380–9393. (95)

Leijtens, T.; Eperon, G. E.; Pathak, S.; Abate, A.; Lee, M. M.; Snaith, H. J. Overcoming Ultraviolet Light Instability of Sensitized TiO2 with Meso-Superstructured Organometal Tri-Halide Perovskite Solar Cells. Nat. Commun. 2013, 4, 2885.

(96)

Klein-Kedem, N.; Cahen, D.; Hodes, G. Effects of Light and Electron Beam Irradiation on Halide Perovskites and Their Solar Cells. Acc. Chem. Res. 2016, 49 (2), 347–354.

(97)

Zhao, Y.; Wei, J.; Li, H.; Yan, Y.; Zhou, W.; Yu, D.; Zhao, Q. A Polymer Scaffold for Self-Healing Perovskite Solar Cells. Nat. Commun. 2016, 7, 10228.

(98)

Kaltenbrunner, M.; Sekitani, T.; Reeder, J.; Yokota, T.; Kuribara, K.; Tokuhara, T.; Drack, M.; Schwödiauer, R.; Graz, I.; Bauer-Gogonea, S.; et al. An Ultra-Lightweight 53



Page 54 of 57

Design for Imperceptible Plastic Electronics. Nature 2013, 499 (7459), 458–463. (99)

Shih, C.-C.; Lee, W.-Y.; Chen, W.-C. Nanostructured Materials for Non-Volatile Organic Transistor Memory Applications. Mater. Horizons 2016, 3 (4), 294–308.

(100) Gelinck, G. H.; Huitema, H. E. A.; van Veenendaal, E.; Cantatore, E.; Schrijnemakers, L.; van der Putten, J. B. P. H.; Geuns, T. C. T.; Beenhakkers, M.; Giesbers, J. B.; Huisman, B.-H.; et al. Flexible Active-Matrix Displays and Shift Registers Based on Solution-Processed Organic Transistors. Nat. Mater. 2004, 3 (2), 106–110. (101) Xue, G.; Wu, J.; Fan, C.; Liu, S.; Huang, Z.; Liu, Y.; Shan, B.; Xin, H. L.; Miao, Q.; Chen, H.; et al. Boosting the Electron Mobility of Solution-Grown Organic Single Crystals via Reducing the Amount of Polar Solvent Residues. Mater. Horizons 2016, 3 (2). (102) Li, H.; Xue, G.; Wu, J.; Zhang, W.; Huang, Z.; Xie, Z.; Xin, H. L.; Wu, G.; Chen, H.; Li, H. Long-Range Ordering of Composites for Organic Electronics: TIPS-Pentacene Single Crystals with Incorporated Nano-Fibers. Chinese Chem. Lett. 2017. (103) Xue, G.; Fan, C.; Wu, J.; Liu, S.; Liu, Y.; Chen, H.; Xin, H. L.; Li, H. Ambipolar Charge Transport of TIPS-Pentacene Single-Crystals Grown from Non-Polar Solvents.

Mater. Horizons 2015, 2 (3). (104) Huang, Z.-T.; Xue, G.-B.; Wu, J.-K.; Liu, S.; Li, H.-B.; Yang, Y.-H.; Yan, F.; Chan, P. K. L.; Chen, H.-Z.; Li, H.-Y. Electron Transport in Solution-Grown TIPS-Pentacene Single Crystals: Effects of Gate Dielectrics and Polar Impurities. Chinese Chem. Lett. 2016, 27 (12). (105) Wu, J.; Fan, C.; Xue, G.; Ye, T.; Liu, S.; Lin, R.; Chen, H.; Xin, H. L.; Xiong, R.-G.; Li, 54


Page 55 of 57 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


H. Interfacing Solution-Grown C 60 and (3-Pyrrolinium)(CdCl 3 ) Single Crystals for High-Mobility Transistor-Based Memory Devices. Adv. Mater. 2015, 27 (30), 4476– 4480. (106) Podzorov, V.; Menard, E.; Borissov, A.; Kiryukhin, V.; Rogers, J. A.; Gershenson, M. E. Intrinsic Charge Transport on the Surface of Organic Semiconductors. Phys. Rev. Lett. 2004, 93 (8), 86602. (107) Xie, W.; Willa, K.; Wu, Y.; Häusermann, R.; Takimiya, K.; Batlogg, B.; Frisbie, C. D. Temperature-Independent Transport in High-Mobility Dinaphtho-Thieno-Thiophene (DNTT) Single Crystal Transistors. Adv. Mater. 2013, 25 (25), 3478–3484. (108) Jurchescu, O. D.; Popinciuc, M.; van Wees, B. J.; Palstra, T. T. M. Interface-Controlled, High-Mobility Organic Transistors. Adv. Mater. 2007, 19 (5), 688–692. (109) Jacobs, H. O.; Whitesides, G. M.; Podzorov, V.; Menard, E.; Willett, R. L.; Someya, T.; Gershenson, M. E.; Rogers, J. A. Submicrometer Patterning of Charge in Thin-Film Electrets. Science (80-. ). 2001, 291 (5509), 1763–1766. (110) Minemawari, H.; Yamada, T.; Matsui, H.; Tsutsumi, J.; Haas, S.; Chiba, R.; Kumai, R.; Hasegawa, T. Inkjet Printing of Single-Crystal Films. Nature 2011, 475 (7356), 364– 367. (111) Diao, Y.; Tee, B. C. K.; Giri, G.; Xu, J.; Kim, D. H.; Becerril, H. A.; Stoltenberg, R. M.; Lee, T. H.; Xue, G.; Mannsfeld, S. C. B.; et al. Solution Coating of Large-Area Organic Semiconductor Thin Films with Aligned Single-Crystalline Domains. Nat. Mater. 2013,

12 (7), 665–671. (112) Takeya, J.; Yamagishi, M.; Tominari, Y.; Hirahara, R.; Nakazawa, Y.; Nishikawa, T.; 55



Page 56 of 57

Kawase, T.; Shimoda, T.; Ogawa, S. Very High-Mobility Organic Single-Crystal Transistors with in-Crystal Conduction Channels. Appl. Phys. Lett. 2007, 90 (10), 102120. (113) Li, H. Y.; Tee, B. C. K.; Giri, G.; Chung, J. W.; Lee, S. Y.; Bao, Z. N. High-Performance Transistors and Complementary Inverters Based on Solution-Grown Aligned Organic Single-Crystals. Adv. Mater. 2012, 24 (19), 2588–2591. (114) Li, H. Y.; Tee, B. C. K.; Cha, J. J.; Cui, Y.; Chung, J. W.; Lee, S. Y.; Bao, Z. N. High-Mobility Field-Effect Transistors from Large-Area Solution-Grown Aligned C-60 Single Crystals. J. Am. Chem. Soc. 2012, 134 (5), 2760–2765. (115) Moon, H.; Seong, H.; Shin, W. C.; Park, W.-T.; Kim, M.; Lee, S.; Bong, J. H.; Noh, Y.-Y.; Cho, B. J.; Yoo, S.; et al. Synthesis of Ultrathin Polymer Insulating Layers by Initiated Chemical Vapour Deposition for Low-Power Soft Electronics. Nat. Mater. 2015, 14 (6), 628–635. (116) Dumas, C.; El Zein, R.; Dallaporta, H.; Charrier, A. M. Autonomic Self-Healing Lipid Monolayer: A New Class of Ultrathin Dielectric. Langmuir 2011, 27 (22), 13643– 13647. (117) Wu, T.; Chen, B. A Mechanically and Electrically Self-Healing Graphite Composite Dough for Stencil-Printable Stretchable Conductors. J. Mater. Chem. C 2016, 4 (19), 4150–4154. (118) Odom, S. A.; Chayanupatkul, S.; Blaiszik, B. J.; Zhao, O.; Jackson, A. C.; Braun, P. V.; Sottos, N. R.; White, S. R.; Moore, J. S. A Self-Healing Conductive Ink. Adv. Mater. 2012, 24 (19), 2578–2581. 56


Page 57 of 57 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


(119) Peng, X.; Liu, Y.; Bentley, W. E.; Payne, G. F. Electrochemical Fabrication of Functional Gelatin-Based Bioelectronic Interface. Biomacromolecules 2016, 17 (2), 558–563. (120) Banerjee, S.; Tripathy, R.; Cozzens, D.; Nagy, T.; Keki, S.; Zsuga, M.; Faust, R. Photoinduced Smart, Self-Healing Polymer Sealant for Photovoltaics. ACS Appl. Mater. Interfaces 2015, 7 (3), 2064–2072. (121) Bubel, S.; Menyo, M. S.; Mates, T. E.; Waite, J. H.; Chabinyc, M. L. Schmitt Trigger Using a Self-Healing Ionic Liquid Gated Transistor. Adv. Mater. 2015, 27 (21), 3331– 3335. (122) Xing, L.; Li, Q.; Zhang, G.; Zhang, X.; Liu, F.; Liu, L.; Huang, Y.; Wang, Q. Self-Healable Polymer Nanocomposites Capable of Simultaneously Recovering Multiple Functionalities. Adv. Funct. Mater. 2016, 26 (20), 3524–3531.

TOC graphic

57


Self-Healing Electronic Materials for a Smart and Sustainable Future

Recommend Documents