Alkali-Metal-Intercalated Aromatic Hydrocarbon Conductors - ACS

Subscriber access provided by TULANE UNIVERSITY

Letter

Alkali-Metal-Intercalated Aromatic Hydrocarbon Conductors Ying-Shi Guan, Yong Hu, Yulong Huang, Anthony Francis Cannella, Changning Li, Jason N. Armstrong, and Shenqiang Ren ACS Appl. Nano Mater., Just Accepted Manuscript • DOI: 10.1021/acsanm.9b00023 • Publication Date (Web): 13 Feb 2019 Downloaded from http://pubs.acs.org on February 13, 2019

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 19 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 Nano Materials

Alkali-Metal-Intercalated Aromatic Hydrocarbon Conductors Ying-Shi Guan,†,∥ Yong Hu,†,∥ Yulong Huang,† Anthony F. Cannella,& Changning Li,† Jason N. Armstrong,† and Shenqiang Ren†,*

†Department

of Mechanical and Aerospace Engineering, Research and Education in Energy,

Environment & Water (RENEW) Institute, University at Buffalo, The State University of New York, Buffalo, New York 14260, United States. &Department

of Chemistry, University at Buffalo, State University of New York, Buffalo, New

York 14260, USA. ∥These

authors contributed equally.

ACS Paragon Plus Environment

1

ACS Applied Nano Materials 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 19

ABSTRACT The structural organization and the determination of the intercalant nature are necessary for the understanding of the band structure and electronic activities in alkali-metal-intercalated aromatic molecular crystals. Here we report the effective conjugation extension and potassium intercalation on the conductivity of polyphenyls (biphenyl, p-terphenyl, and p-quaterphenyl), among which the metallic conductivity is observed in potassium intercalated p-quarterphenyl. The conductivity increases with an increase in the length of paraphenylene repeating units, while the mechanistic studies uncover the intercalation nature between alkali-metal and paraphenylene repeating units through electron and Raman spectroscopies, and thermal analysis. The charge-transfer structures are described on the characteristics of the radical formation and polaron-bipolaron transitions, while the partial chemical bonds between potassium and the paraphenylene chains are resulted from the hybridization between the s orbitals of potassium and the p orbitals of phenylene. The studies herein provide insights into understanding the roles of and conjugation length on charge transport properties of aromatic molecular crystals.

Keywords: alkali-metal; molecular conductor; intercalation; metallic conducting; radical formation; polycyclic aromatic hydrocarbons


2

Page 3 of 19 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


1. Introduction Molecular aromatic hydrocarbons are very promising for the applications in molecular electronics, and their alkali-metal intercalants have shown many quantum phenomena, such as strongly correlated electron nature.1 This makes alkali-metal-intercalated hydrocarbons appealing for developing molecular conductors and even superconductors in quantum materials and electronics. Strongly correlated electronic molecules will promote their application in nanoscience enabling their biggest impact include electronic, electro-optic and optical devices. The transition from semiconductor technology to nanoscale devices has anticipated improved properties and resolution, Data storage devices based on nanostructures provide smaller, faster, and lower consumption systems. However, metallic-like electrical transport in such chain-link hydrocarbons remains extremely rare, because of their intrinsic insulating nature.2-5 While the defects largely affect the conductivity, resulting in localized electronic states which can alter the transport mechanism from band-like to thermally activated hopping. As a result, over several decades of materials developments, only a few molecular charge-transfer materials have shown the metallic conductivity.6-10 To address these challenges, the oxidative or reductive doping method producing unpaired electrons can open a partially filled conduction band, where charge carriers drift with minimal scattering to introduce metallicity into molecular system.1, 2, 11-15 Recently, alkali-metal doped aromatic hydrocarbons have drawn extensive attention due to their strongly correlated electrons nature.1,3, 16 Very recently, the potassium-doped p-terphenyl exhibited high temperature superconductivity with Tc above 120 K was reported. A superconducting-gaplike feature appeared in the K-doped single crystal of p-terphenyl.16 In this context, alkali-metal doped aromatic hydrocarbons materials have shown metallic conductivity17 and even superconductivity.3, 11, 18, 19 However, the inhomogeneous morphology of conductive polymers leads to the disorder-induced electronic localization and percolation.14 In addition, the intercalation level can influence the percolating networks that dominate the charge transport properties in such materials.1 It is therefore indispensable to study the intercalation level and effective chain length effects on the charge transport properties for the purpose of elucidating the origin of the conducting networks in aromatic hydrocarbons. Here we report the influence of potassium intercalation level and conjugation chain length in the electrical conductivity of potassium intercalated polycyclic aromatic hydrocarbons (paraphenylene oligomers, such as biphenyl, p-terphenyl and pquaterphenyl). As increasing the intercalation level and chain length, the conductivity can be


3


Page 4 of 19

switched by a large degree while the optimum metallic conductivity is shown in potassium intercalated p-quaterphenyl solids with 4:1 molar ratio between potassium and p-quaterphenyl. Electron paramagnetic resonance (EPR) and Raman spectroscopy illustrate the relationship between the radical formation and polaron-bipolaron transition for the control of electrical conductivity. The potassium intercalated p-quaterphenyl solids with 4:1 molar ratio exhibit metallic-like charge transport properties.

2. Experimental section 2.1 Materials and instruments.

Potassium, biphenyl, p-terphenyl, and p-quarterphenyl were purchased from SigmaAldrich and sintered by solid state reactions. The SEM images were taken on FEI Quanta 450 FEG. UV-Vis spectrum was recorded on an Agilent Model HP8453 UV-vis spectrophotometer. Keithley 2400 SourceMeter was used to measure current versus voltage curves. Current probes and voltage probes were contacted to samples parallelly and width and length between probes were about 5 mm and height of sample was about 3 mm. Temperature dependence of resistance measurements were carried out by fourprobe method with a Keithley 2400 constant current source. EPR spectra were collected using a Bruker EMX EPR spectrometer at room-temperature. Samples for EPR


4

Page 5 of 19 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


measurements were prepared in a glove box with nitrogen filled. ATR-FTIR results were collected on a Bruker Alpha FTIR Spectrometer in an argon filled glove box.

2.2 The synthesis of the K doped p-oligophenyls samples.

Potassium doped biphenyl, p-terphenyl, and p-quarterphenyl were synthesized by solid state reactions. Several small pieces of pure potassium lumps and p-oligophenyls powder with different mole ratios were sealed in a glass tube. The glass tube was evacuated by a turbo molecular pump and sealed by a gas torch. The evacuated glass tube was sintered at different temperature for 48 hours.

2.3 The preparation of pellet samples of K doped p-oligophenyls. Potassium doped p-oligophenyls pellets were prepared by grinding the sintered materials and pressing them into a pellet (0.25 inch in diameter) at a pressure of one ton in a glove box. Then four copper wires were connected on to the samples as electrodes using silver epoxy.

3. Results and Discussion Paraphenylene oligomers (biphenyl, p-terphenyl and p-quarterphenyl, Figure 1a) are made of two, three and four phenyl rings connected by single C-C bond in para position.20 We select these three oligomers to demonstrate the chain length effect of molecular oligomers on the alkali metal


5


Page 6 of 19

intercalation and percolation network formation for the switchable conductivity. The potassium intercalated paraphenylene oligomers with different molar ratios are prepared through solid state sintering reactions at different temperatures (Figure 1a). To understand the percolation network formation from the solid state sintering, we firstly investigate the influence of sintering temperature on the conductivity of potassium intercalated paraphenylene oligomers at a constant doping concentration (potassium : biphenyl = 2 : 1(K-BP), potassium : p-terphenyl = 3 : 1(K-TP), and potassium : p-quaterphenyl = 4 : 1(K-QP)). Potassium intercalation between the molecular planes of paraphenylene can be tuned through the control of solid state sintering. As shown in Figure 1b, the optimum conductivity for K-BP, K-TP, and K-QP are sintered at 450 K, 570 K and 590 K, respectively. It should be noted that the optimum sintering temperature of a paraphenylene oligomer is higher than its melting point and lower than the boiling point to achieve potassium intercalation induced percolation networks for the optimum conductivity (Figure 1c). If the sintering temperature is lower than the melting point, the potassium intercalation between the paraphenylene oligomer layers is hard to trigger. A sintering temperature higher but close to the melting point can induce the potassium intercalation between the paraphenylene oligomer layers to form the conducting network. While further increasing the sintering temperature even higher than the boiling point of the paraphenylene oligomers is not conducive for the formation of chargetransfer percolation conducting networks, which could be due to the significant evaporation of paraphenylene oligomers above their boiling point. That’s why the temperature dependent conductivity of potassium doped paraphenylene oligomer exhibited the trend showed in Figure 1b. We select K-TP samples sintered at different temperatures to validate our hypothesis. The scanning electron microscopy (SEM) images of K-TP sample sintered at 570 K exhibit a continuous and compact morphology (Figure 1d). The morphology of K-TP sintered at 450 K exhibits the visible surface defects, while the sample sintered at 620 K shows a loose structure with non-uniform granular powder geometry. The inhomogeneous and non-uniform morphology leads to the poor charge transport properties for the samples sintered at 450 K and 620 K. Similar phenomena are observed in the K-BP and K-QP (Figure S2-S3). The optimum samples of K-BP, K-TP and K-QP are achieved at 450 K, 570 K, and 590 K, respectively, for the following studies. The metallic conductivity of potassium doped aromatic hydrocarbons is related to the formation of polarons.20-22 Raman spectroscopy provides an effective way to identify the structure and dynamics of polarons that contribute to the metallic conductivity of potassium doped


6

Page 7 of 19 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


paraphenylene oligomers. Pristine biphenyl, p-terphenyl and p-quartphenyl show several Raman active modes, including stretching, bending (in-plane deformation), rocking (out-of-plane deformation). The Raman spectroscopy of potassium doped paraphenylene oligomers show significant changes after doping with potassium and the similar characteristic peaks of polaron (Figure 2a). The inter-ring C-C stretching of the pristine biphenyl (1,590 and 1,608 cm-1), pterphenyl (1,591 and 1,602 cm-1) and p-quartphenyl (1,593 and 1,605 cm-1) merge to the polaronic groups centered at 1,594 , 1,596 and 1,599 cm−1 for K-BP, K-TP, and K-QP, respectively (Figures S4-6). The C-H stretching region is the strongest feature in the Raman spectra of pristine samples. The C-H frequencies usually do not change in any obvious fashion with changes of structure, but are significantly affected by the intermolecular interaction. Our previous study on potassium intercalated p-terphenyl shows that when potassium is intercalated into p-terphenyl molecules, the molecule loses its symmetry and becomes a dipole. The dipolar interaction between the potassium doped p-terphenyl molecules would affect the C-H frequencies. As shown in Figure 2a, after intercalating potassium into aromatic hydrocarbons, the modes in the C-H stretching region of potassium doped aromatic hydrocarbons shift to lower frequency, indicating the possible dipole interactions between the intercalated polyphenyls. To further study the carrier-generation mechanism that leading to metallic conduction, we study the magnetic spin coupling by EPR measurements. The pristine paraphenylene oligomers are intrinsically insulating molecules with no electron spin resonance signals. Figure 2b shows the EPR spectra of K-BP, K-TP and K-QP, which exhibit a classic Lorentzian shape at room temperature, revealing the formation of radicals in potassium intercalated polyphenyls.23 The formation of radicals, corresponding to polarons, contributes to high electrical conductivity of the potassium intercalated paraphenylene oligomers.21 In addition, the potassium doped paraphenylene oligomers show different g-factor, which are 1.9898, 1.9881 and 1.9869 for K-BP, K-TP, and K-QP, respectively. The g-factor continuously decreases with increasing the number of benzene rings, indicating an enhanced spinorbit. EPR measurements clarified that polarons with ½ spin number emerged after the potassium intercalating into paraphenylene oligomers and act as the conducting carriers. We further investigate the effect of intercalation level on the conductivity of K-BP, K-TP and KQP, as a variation from the chain length. As shown in Figure 3a, the numbers of benzene rings of oligomers are related to the potassium intercalation ratios. We employ the standard four-probe


7


Page 8 of 19

method to monitor the resistance change of K-BP, K-TP and K-QP. The optimum conductivity of 2.5 Ω-1cm-1, 3.57 Ω-1cm-1, and 10.1 Ω-1cm-1 for K-BP, K-TP and K-QP respectively are achieved with molar ratios of 2:1, 3:1 and 4:1 (Figure 3b and 3c). Pristine paraphenylene oligomers exhibit insulating behaviors due to their large bandgaps. However, after potassium intercalation, the charge transfer from potassium to molecular oligomer decreases the band gap due to the formation of polaron or bipolaron band in the middle of valance and conducting band, which results in a transition from insulating to semiconducting characteristics (Inset of Figure 3c). With the increase of potassium intercalation, the bandgap becomes smaller, leading to the increased conductivity. The molar ratios of K-BP, K-TP and K-QP at 2:1, 3:1, and 4:1 contribute to an optimum value of conductivity for biphenyl, p-terphenyl and p-quarterphenyl, respectively. While further increasing the potassium intercalation, the filled band turns to be insulating again. The temperature dependent resistance measurements for K-BP, K-TP and K-QP are shown in Figure 3d, in which the K-BP and K-TP exhibit the increase of resistance as decreasing the temperature, while a typically metallic behavior in K-QP. The resistance of K-QP is found to be 5.6 Ω at 300 K, while further decreases to 1.5 Ω at 100 K. Figure 3e shows the current-voltage (I-V) characteristics of K-QP at different temperatures, where the current changes linearly with the voltage. These behaviors confirm its metallic conduction property of K-QP. A possible reason is that the number of benzene ring in K-QP is bigger than K-BP and K-TP, which can lead to much more potassium intercalation. The large amount of the potassium lead to the metallic conductive behavior. Previous reports suggest that with the increase of potassium intercalation, the polarons interact to produce the correlated charged-soliton-charged-antisoliton pairs (bipolaron) in alkali-metal-intercalated poligophenyls.14, 17, 22 The interaction between bipolarons can lead to a highly conductive network, leading to its metallic behavior across a broad temperature range. The K-QP can be stable over 30 days, which is illustrated in Figure 3f, showing a negligible difference in the resistance. To understand the metallic conduction in K-QP, we further conduct the EPR measurements on the K-QP samples with different intercalation levels. As shown in Figure 4a, K-QP sintered at 590 K reveals a high density of radical ions, in comparison to that of K-QP sintered at 550 K, and 650 K. The g factor continuously decreases with increasing the sintering temperature, indicating an enhanced spin-orbit coupling with increasing the benzene ring. The g-factor is 1.9886, 1.9869 and 1.9858 for K-QP sintered at 550 K, 590 K and 650 K, respectively. The weak spin-orbit coupling for electrons in the sample prepared at 550 K might come from the low intercalation level of


8

Page 9 of 19 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


potassium due to the low sintering temperature. The strong spin-orbit coupling for electrons in KQP sintered at 650 K might come from the formed chemical bond at high temperature. The sintering temperature dependences of EPR intensity further support the assumptions. K-QP sample with a low sintering temperature of 550 K shows a weaker EPR signal intensity. As the sintering temperature increase to 590 K, more potassium can be intercalated into p-quaterphenyl and a stronger EPR signal is obtained. However, when the sintering temperature is further increased to 650 K, the charger-transfer interaction between potassium atoms and p-quaterphenyl molecules tends to form a chemical interaction. Thus, the unpaired electrons in potassium atoms tends to be paired through the covalent interaction, which results in a lower unpaired electron level. The sintering temperature during solid state reactions indeed controls the intercalation level, which in turn dictates the formation of radicals for the switchable conductivity in K-QP. To facilitate the understanding of sintering temperature effect on the formation of K-QP, we further carry out the thermogravimetric analysis (TGA) to investigate the intercalation effect on the electrical transport in K-QP. Figure 4c shows the TGA data of K-QP sintered at 550 K, 590 K and 650 K, respectively. The 550 K sintered K-QP shows a poor stability, which continuously decomposes as increasing the temperature. The 590 K sintered K-QP performs as the formation of K-quarterphenyl chargetransfer complex, while the p-quaterphenyl decomposes and evaporates as the temperature above its boiling point of about 700 K. However, the 650 K sintered K-QP exhibits highly thermal stability without the weight loss even at 770 K, indicating the strongly interacted potassium-pquaterphenyl compound. The thermal stability of K-QP sintered at different temperatures suggests the variation of potassium intercalation levels for the formation of charge-transfer complex, while a relatively high sintering temperature close to the boiling point tends to enhance the charger transfer interaction, which can account for the high thermal stability in 650 K sintered K-QP. The absorption spectra of K-QP sintered at different temperatures are shown in Figure 4b, which are closely related to the electronic transition features in K-QP. The 590 K sintered K-QP have two new absorption bands at 720 nm and 960 nm, which could be resulted from the formation of polaron band.22 Meanwhile, the intensity of 650 K sintered K-QP at 720 nm and 960 nm is much lower than that of the 590 K sintered sample, which can be attributed to the partial decomposition of charger-transfer complex at a high temperature. The morphologies of K-QP sintered at 550 K, 590 K and 650 K exhibit the drastic differences (Figure 4d). The K-QP sintered at 590 K have the


9


Page 10 of 19

uniformly consolidated morphology, while the other two samples exhibit a loose void structure, suggesting the optimum conductivity in K-QP at 590 K.

4. Conclusions The intercalation level and conjugation chain length play an important role in the charge transport of potassium-intercalated polyphenyls. The intrinsic insulating polyphenyls exhibit metallic conductivity after potassium intercalation at nanoscale, in which the potassium intercalation level and conjugation chain length play an important role in the electrical conductivity of potassiumintercalated polyphenyls (such as biphenyl, p-terphenyl, and p-quaterphenyl). Particularly, potassium intercalated p-quarterphenyl exhibits metallic conductivity with the resistivity of 0.25 Ωcm at room temperature - a monotonic decrease in resistivity with temperature - as decreasing the temperature, its resistivity further decreased to 0.1 Ωcm.

FIGURES & CAPTIONS


10

Page 11 of 19 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


Figure 1. Structural and electrical characterization of potassium intercalated polyphenyls. (a) The chemical structure of the paraphenylene oligomers and the schematic diagram of potassium-doped paraphenylene oligomers solid. (b) The conductivity of the potassium-doped paraphenylene oligomers solid at different processing temperature (potassium : biphenyl = 2 : 1(K-BP), potassium : p-terphenyl = 3 : 1(K-TP), and potassium : p-quaterphenyl = 4 : 1(K-QP)). (c) The relationship of the optimum temperature for K-BP, K-TP, and K-QP with the melting points and boiling points of polyphenyls. (d) The SEM images of the K-TP (potassium : p-terphenyl = 3 : 1) samples sintered at different temperature (from up to down is 450 K, 570 K, and 620 K, respectively).


11


Page 12 of 19

Figure 2. Raman and EPR study of potassium intercalated polyphenyls. (a) Raman spectra, (b) EPR spectra of K-BT, K-PT and K-QT samples sintered at 450 K, 570 K, and 590 K, respectively.


12

Page 13 of 19 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


Figure 3. Electrical characterization of potassium intercalated polyphenyls. (a) The schematic diagram for potassium intercalated p-quarterphenyl. (b) The conductivity of the K-BP, K-TP, and K-QP samples at different potassium doping level. (c) The conductivity of the K-BP, K-TP, and K-QP samples at the optimum doping level, (potassium : biphenyl = 2 : 1(K-BP), potassium : pterphenyl = 3 : 1(K-TP), and potassium : p-quaterphenyl = 4 : 1(K-QP)). Inset shows the schematic figure for the band structure for pristine and potassium doped polyphenyls, valance band (VB), conducting band (CB).(d) The representative temperature dependent resistance of the K-BP, KTP, and K-QP samples at the optimum doping level. (e) The representative of the current-voltage (I-V) curves of the K-QP samples at different temperatures. (f) The current-voltage (I-V) curves of the K-QP sample after stored in a glove box for 30 days.


13


Page 14 of 19

Figure 4. The EPR, morphology, packing, optical, TGA study of K-QP sample (potassium : pquaterphenyl = 4 : 1) (a) The EPR spectra of the K-QP samples at different sintered temperature. (b) The absorption spectra of the K-QP samples at different sintered temperature. (c) The TGA data of the K-QP samples at different sintered temperature. (d) The Scanning electron microscopy images of the K-QP samples at different sintered temperatures.


14

Page 15 of 19 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


ASSOCIATED CONTENT Supporting Information. The following files are available free of charge. SEM images and EPR spectra of potassium intercalated paraphenylene oligomers, Raman spectra of paraphenylene oligomers.

AUTHOR INFORMATION Corresponding Author *E-mail: [email protected]. Notes The authors declare no competing financial interest. ACKNOWLEDGMENT The U.S. Department of Energy, Office of Basic Energy Sciences, Division of Materials Sciences and Engineering supports S.R. under Award DE-SC0018631 (Organic conductors). Financial support was provided by the U.S. Army Research Office supports S.R. under Award W911NF-182-0202 (Materials-by-Design and Molecular Assembly.


15


Page 16 of 19

REFERENCES (1) Kubozono, Y.; Mitamura, H.; Lee, X.; He, X.; Yamanari, Y.; Takahashi, Y.; Suzuki, Y.; Kaji, Y.; Eguchi, R.; Akaike, K.; Kambe, T.; Okamoto, H.; Fujiwara, A.; Kato, T.; Kosugi, T.; Aoki, H., Metal-intercalated Aromatic Hydrocarbons: A New Class of Carbon-Based Superconductors. Phys. Chem. Chem. Phys. 2011, 13, 16476-16493. (2) Wang, P.; Lin, S.; Lin, Z.; Peeks, M. D.; Van Voorhis, T.; Swager, T. M., A Semiconducting Conjugated Radical Polymer: Ambipolar Redox Activity and Faraday Effect. J. Am. Chem. Soc. 2018, 140, 10881-10889. (3) Rosseinsky, M. J.; Prassides, K., Materials science: Hydrocarbon Superconductors. Nature 2010, 464, 39-41. (4) Lee, K.; Cho, S.; Park, S. H.; Heeger, A. J.; Lee, C. W.; Lee, S. H., Metallic Transport in Polyaniline. Nature 2006, 441, 65-68. (5) Faramarzi, V.; Niess, F.; Moulin, E.; Maaloum, M.; Dayen, J. F.; Beaufrand, J. B.; Zanettini, S.; Doudin, B.; Giuseppone, N., Light-Triggered Self-Construction of Supramolecular Organic Nanowires as Metallic Interconnects. Nat. Chem. 2012, 4, 485-490. (6) Alves, H.; Molinari, A. S.; Xie, H.; Morpurgo, A. F., Metallic Conduction at Organic ChargeTransfer Interfaces. Nat. Mater. 2008, 7, 574-580. (7) Ivory, D. M.; Miller, G. G.; Sowa, J. M.; Shacklette, L. W.; Chance, R. R.; Baughman, R. H., Highly Conducting Charge‐Transfer Complexes of Poly(p‐phenylene). J. Chem. Phys. 1979, 71, 1506-1507. (8) Shacklette, L.; Eckhardt, H.; Chance, R.; Miller, G.; Ivory, D.; Baughman, R., Solid‐State Synthesis of Highly Conducting Polyphenylene from Crystalline Oligomers. J. Chem. Phys. 1980, 73, 4098-4102. (9) Wudl, F., From organic metals to superconductors: Managing Conduction Electrons in Organic Solids. Acc. Chem. Res. 1984, 17, 227-232. (10) Torrance, J. B., The Difference between Metallic and Insulating Salts of Tetracyanoquinodimethone (TCNQ): How to Design An Organic Metal. Acc. Chem. Res. 1979, 12, 79-86. (11) Haddon, R. C.; Hebard, A. F.; Rosseinsky, M. J.; Murphy, D. W.; Duclos, S. J.; Lyons, K. B.; Miller, B.; Rosamilia, J. M.; Fleming, R. M.; Kortan, A. R.; Glarum, S. H.; Makhija, A.


16

Page 17 of 19 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


V.; Muller, A. J.; Eick, R. H.; Zahurak, S. M.; Tycko, R.; Dabbagh, G.; Thiel, F. A., Conducting Films of C60 and C70 by Alkali-Metal Doping. Nature 1991, 350, 320-322. (12) Moulin, E.; Niess, F.; Maaloum, M.; Buhler, E.; Nyrkova, I.; Giuseppone, N., The Hierarchical Self-Assembly of Charge Nanocarriers: A Highly Cooperative Process Promoted by Visible Light. Angew. Chem. Int. Ed. 2010, 49, 6974-6978. (13) Armao, J. J. t.; Maaloum, M.; Ellis, T.; Fuks, G.; Rawiso, M.; Moulin, E.; Giuseppone, N., Healable Supramolecular Polymers as Organic Metals. J. Am. Chem. Soc. 2014, 136, 1138211388. (14) Kohlman, R. S.; Zibold, A.; Tanner, D. B.; Ihas, G. G.; Ishiguro, T.; Min, Y. G.; MacDiarmid, A. G.; Epstein, A. J., Limits for Metallic Conductivity in Conducting Polymers. Phys. Rev. Lett. 1997, 78, 3915-3918. (15) Guan, Y.-S.; Zhang, Z.; Tang, Y.; Yin, J.; Ren, S., Kirigami-Inspired Nanoconfined Polymer Conducting Nanosheets with 2000% Stretchability. Adv. Mater. 2018, 30, 1706390. (16) Liu, W.; Lin, H.; Kang, R.; Zhu, X.; Zhang, Y.; Zheng, S.; Wen, H.-H., Magnetization of Potassium-Doped P-Terphenyl and P-Quaterphenyl by High-Pressure Synthesis. Phys. Rev. B 2017, 96, 224501. (17) Péres, L. O.; Spiesser, M.; Froyer, G., Reduction of P-Terphenyl, P-Quaterphenyl and PSexiphenyl using Alkali Metal in Liquid Ammonia: Process and Characterization of the Reduced Compounds. Synth. Metal. 2005, 155, 450-454. (18) Wudl, F., From Organic Metals to Superconductors: Managing Conduction Electrons in Organic Solids. Acc. Chem. Res. 2002, 17, 227-232. (19) Baskaran, G., Two Mott Insulator Theory of Superconductivity in K3X (X: picene, .. pterphenyl, .. C60). arXiv:1704.08153 2017. (20) Furukawa, Y.; Ohtsuka, H.; Tasumi, M., Raman Studies of Polarons and Bipolarons in Sodium-Doped Poly-P-Phenylene. Synth. Met. 1993, 55, 516-523. (21) Crecelius, G.; Stamm, M.; Fink, J.; Ritsko, J. J., AsF5-Doped Polyparaphenylene: Evidence for Polaron and Bipolaron Formation. Phys. Rev. Lett. 1983, 50, 1498-1500. (22) Bredas, J. L.; Street, G. B., Polarons, Bipolarons, and Solitons in Conducting Polymers. Acc. Chem. Res. 1985, 18, 309-315.


17


Page 18 of 19

(23) Kispert, L. D.; Joseph, J.; Miller, G. G.; Baughman, R. H., EPR Study of Polarons in A Conducting Polymer with Nondegenerate Ground States: Alkali Metal Complexes of Poly (p‐phenylene) and Phenylene Oligomers. J. Chem. Phys. 1984, 81, 2119-2125.


18

Page 19 of 19 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


TOC


19

Alkali-Metal-Intercalated Aromatic Hydrocarbon Conductors - ACS

Recommend Documents