Fluorinated Spacers Regulate the Emission and Bandgap of Two

Subscriber access provided by Nottingham Trent University

Surfaces, Interfaces, and Catalysis; Physical Properties of Nanomaterials and Materials

Fluorinated Spacers Regulate the Emission and Bandgap of Two Dimensional Single Layered Lead Bromide Perovskites by Hydrogen Bonding Binbin Luo, Yan Guo, Yonghong Xiao, Xin Lian, Tongtong Tan, Dehai Liang, Xianli Li, and Xiao-Chun Huang J. Phys. Chem. Lett., Just Accepted Manuscript • DOI: 10.1021/acs.jpclett.9b02172 • Publication Date (Web): 23 Aug 2019 Downloaded from pubs.acs.org on August 23, 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 20 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

The Journal of Physical Chemistry Letters

Fluorinated Spacers Regulate the Emission and Bandgap of Two Dimensional Single Layered Lead Bromide Perovskites by Hydrogen Bonding Binbin Luoa,b,*, Yan Guoa, Yonghong Xiaoa, Xin Liana, Tongtong Tana, Dehai Lianga, Xianli Lia, and Xiaochun Huanga,b,*

a

Department of Chemistry and Key Laboratory for Preparation and Application of Ordered

Structural Materials of Guangdong Province, Shantou University, Shantou, Guangdong 515063, China b

Guangdong Provincial Laboratory of Chemistry and Fine Chemical Engineering, Shantou, 515063, China

Corresponding Author: [email protected], [email protected].

ACS Paragon Plus Environment

1

The Journal of Physical Chemistry Letters 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 20

ABSTRACT: In this work, four kinds of two dimensional single-layered F-substituted ethylammonium lead halide perovskites (LHPs, (FxCH3-xCH2NH3)2PbBr4, x = 0, 1, 2 and 3) are successfully synthesized. The introduction of terminal F atoms promotes the formation of interand intramolecular hydrogen bonding network, which has a great impact on the configuration of F-substituted EA, the interlayer spacing and distortion of inorganic layers. Among these four asprepared samples, (FCH2CH2NH3)2PbBr4 shows the smallest bandgap (~ 2.72 eV) and best photoconductivity due to the interlayer electronic coupling. Owing to the strong coupling between excitons and lattice, intensive white light emission (quantum yield: 12%) is observed for (F2CHCH2NH3)2PbBr4.

Benefiting

from

the

hydrophobic

nature

of

F-C

bonds,

(CF3CH2NH3)2PbBr4 presents a greatly improved stability towards moisture. These findings reveal that constructing inter- and intramolecular interaction can serve as an effective approach to tune the broadband emission and the interlayer conductivity of single layered LHPs.

TOC GRAPHICS


2

Page 3 of 20 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


Layered organic-inorganic lead halide perovskites (LHPs) have been regained enormous attention in the past decade due to their excellent moisture-stability with great potential on optical and electrical applications such as light-emitting diodes (LEDs), photodetectors and solar cells.1-7 The structure of these layered LHPs can be viewed as the periodic segments formed by slicing the three dimensional (3D) ABX3 LHPs along a particular crystallographic plane. The general form of 2D layered LHPs is (RNH3)2An-1BnX3n+1, where RNH3+ represent long spacing cations which can template 2D layers, A is monovalent organic cation exemplified by CH3NH3+ and HC(NH2)+ or inorganic cation such as Cs+, B represents divalent metal ions like Pb2+, Sn2+, Cu2+, et al., X is a halide anion, and n refers to the number of octahedral layers.1, 8-11 2D LHPs allow for not only the substitutions at the B and X sites, but also the replacement of A-site cations with a diversity of aliphatic or aromatic ammonium. Therefore, a wide structural and compositional tuning can be readily achieved in 2D LHPs.12-14 As a natural multiple-quantum-well, 2D LHPs present strong quantum and dielectric confinement effects, resulting in excellent luminescence efficiencies.1-2 Once the photoexcited excitons are coupled with the distorted octahedra, namely self-trapped excitons (STEs), white light is emitted.1 To achieve a highly efficient broadband emission, alkyl ammonium/diammonium cations with variable length or configuration have been adopted to construct corrugated or distorted structure.15-17 In addition, by introducing fluorophores into the organic part of 2D LHPs, a combination of emissions from organic part and inorganic layers can be obtained for diverse optical applications.18 Varying the energy levels of organic and inorganic part is also an efficient way to realize the charge/energy transfer across the organic-inorganic interface, which results in some emissive properties that can not be realized with either component alone.18


3


Page 4 of 20

Besides the great tunability of emission, 2D LHPs usually present better ambient stability than that of 3D organic-inorganic LHPs.19-22 However, the conductivity along the direction perpendicular to the inorganic plane is relatively poor since the bulky organic cations involved in the construction of 2D LHPs are hydrophobic and insulating. By adopting cations with conjugated moieties like pyrene, perylene, naphthalene and benzene, the interlayer charge transfer can be greatly enhanced.6 In addition, it has been reported that spacers with a high dipole moment can promote the separation of photogenerated electron-hole pairs, thereby enhancing the performance of solar cell.23 Therefore, incorporating organic cations with specific functional groups endow 2D LHPs with a great tunability to enhance the optical and electric properties. As for hybrid organic-inorganic 2D LHPs, the presence of hydrogen bond between organic cations and surrounding halogen ions are usually responsible for the distortion of inorganic lattice,24-25 which impacts the optoelctronic properties related to STEs emission and charge-carrier recombination. For example, the insertion of alkyl ammonium groups with strong electronegative atoms such as O, Cl, Br and I can promote the formation of a hydrogen/halogen-bond network between adjacent organic layers, achieving the reduction of interlayer distance and also red-shift of absorption and emission.24-25 As the strongest electronegative atom, F atom plays an important role in constructing inter- or intra-molecular hydrogen bonding. The strong hydrophobic nature of F-C bond can greatly improve the moisture stability of perovskite. Therefore, introducing Fsubstituted organic ammonium cations is expected to not only tune the crystal and electronic structure, but also improve the moisture stability of 2D LHP. In this work, a series of unsubstituted ethylammonium (EA) and F-substituted EA including 2fluoroethylammonium

(FEA),

2,2-difluoroethylammonium

(2FEA)

and

2,2,2-

trifluoroethylammonium (3FEA) are successfully incorporated into 2D LHPs, which are denoted


4

Page 5 of 20 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


as 0FP, 1FP, 2FP and 3FP, respectively. Due to the formation of inter- and intramolecular hydrogen bonding, the magnitude of octahedral distortion and interlayer distance are varied dramatically. 1FP shows the lowest bandgap and best photoconductivity among the four prepared 2D LHPs due to the smallest interlayered distance. An intensive broadband emission with 12.3% photoluminescence (PL) quantum yield (QY) is observed in 2FP, attributed to the great out-ofplane distortion of inorganic layers. Owing to the hydrophobic nature of F-C bond and intermolecular hydrogen bonding, all three F-substituted 2D LHPs exhibit better moisture stability than that of 0FP. The crystal structures of the series samples with bond lengths and angles are illustrated in Figure 1 and detailed structural parameters are provided in Table S1. As a Mn2+ doping host, the structure of 0FP has been reported in our early work.26 All three F-substituted EA cations were successfully co-crystallized with lead bromide into 2D LHPs along (100) orientation in an orthorhombic space system, while 0FP crystalizes in the monoclinic space group P21/c. Different with 0FP, the unit cell in all F-substituted LHPs contains two inorganic layers and two organic bilayers. Interestingly, both 0FP and 2FP show great out-of-plane distortion, while only in-plane distortion is observed in 1FP and 3FP. To quantitatively evaluate the degree of structural distortion, three tilt angles are measured as shown in Figure S1. In contrast with the small distortion of 1FP, 0FP and 2FP show great deformation not only in the stacking plane, but also out of the stacking direction.


5


Page 6 of 20

Figure 1. Crystal structures (left side) and bond lengths/angles (right side) of (a) 0FP, (b) 1FP, (c) 2FP and (d) 3FP.

To investigate the origin of such different tilting in these four kinds of 2D LHPs, the hydrogen bond interaction was investigated since it has been suggested that hydrogen bonds between protonated amino group and surrounding halide are responsible for the local distortion of lead halide octahedron.27 The hydrogen atoms of primary ammonium can interact with either bridging halogens or terminal halogens of octahedron, thereby resulting in different tilting configuration of [PbBr6]4- octahedron.24, 27 We found that one of three hydrogen atoms of primary ammonium is bound to one of the equatorial bromine atoms in the case of 0FP, 2FP and 3FP (Figure 2). The other two hydrogen atoms are directed to adjacent terminal bromine atoms, respectively. This hydrogen bonding (N-H···Br, ~3.3-3.5 Å) results in the great out-of-plan tilting of octahedron,


6

Page 7 of 20 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


while this phenomenon is not observed in 1FP and 3FP, attributed to the mirror-symmetric hydrogen bond at each side of inorganic layers.

Figure 2. Hydrogen bond (dashed lines) interaction between adjacent organic cations and at the organic-inorganic interface for (a) 0FP, (b) 1FP, (c) 2FP and (d) 3FP samples.

The conformation of organic cations in 1FP appears much different, with -CH2CH2NH3+ part of molecule nearly lying in the perovskite cavity. This configuration benefits from both the hydrogen bonding between the hydrogen atoms of methyl group and equatorial bromine (C-H···Br, ~3.86 Å) and the intramolecular hydrogen bonding (N-H···F, ~3.40 Å) with the smallest C-C-N bond angle of 109.419° (Figure 2b), thereby further decreasing the volume of FEA molecule. Moreover, due to the strong interlaced hydrogen bond network among organic cations bilayers, the ammonium groups of FEA are away from the perovskite cavity, which enables the successful implant of whole FEA into the void. The filling of FEA molecule also expands perovskite cavity slightly, leading to a longer average Pb-Br bond length than that of other three 2D LHPs samples (Figure 1). As expected, the introduction of terminal F atom induces the formation of intermolecular hydrogen bond network among organic cations, reducing the interlayer distance of


7


Page 8 of 20

inorganic layers to ~9.76 Å, which is much smaller than that of 0FP, 2FP and 3FP. Compared to the large terminal Br-Br distance of 0FP (6.39 Å), 2FP (7.25 Å) and 3FP (7.50 Å), the interlayer Br-Br distance of 1FP is ~4.47 Å, indicating that a certain 3D characters might occur for this compound.25 Powder X-ray diffraction (PXRD) and scanning electron microscope (SEM) were chosen to analyze the purity and morphology of these synthesized products, as depicted in Figure 3. All the diffraction peaks of prepared samples match well with the corresponding simulated patterns, suggesting the high purity of prepared samples. Transparent sheet-like crystals with millimeter length are observed from the room light photographs (Figure 3b). The edge of these four crystal samples shows wrinkled feature, indicating the layer-by-layer stacking nature of the prepared samples. Interestingly, 1FP crystals show a yellow-green color under room light which is different with other three kinds of crystals presenting white color (Figure 3b). Correspondingly, the photographs of these crystals under UV light exhibit much difference. In contrast with the weak broadband emission of other three samples, a more intensive white light emission occurs for 2FP since out-of-plane distortion will further localized the excitons and increase the self-trapping energy.28 This behavior is consistent with the reported conclusion that white light emission of 2D LHPs correlates tightly with the out-of-plane distortion.29


8

Page 9 of 20 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. (a) Simulated (dotted line) and measured (solid line) PXRD patterns and (b) digital pictures and SEM images of 0FP, 1FP, 2FP and 3FP samples.

Such 2D LHPs always show layer dependent optical properties and distortion of octahedra also result in the trapping of free excitons, leading to a white light emission as observed in Figure 3b. Absorption and photoluminescence (PL) spectra and parameters of the synthesized products are collected and shown in Figure 4a and Table 1. Similar to some reported layered LHPs,30 all four prepared samples exhibit a remarkably sharp absorption edge with two adjacent peaks, indicating a direct bandgap nature for all compounds. The higher energy absorption peak is assigned to the bandgap transition, while the lower one is assigned to the first excitonic absorption.30 Interestingly, the absorption edge of 1FP shifts ~30 nm towards direction of long wavelength and a blue-shift (~20 nm) of excitonic peak is observed for 2FP with respect to the absorption of 0FP sample. Usually, the excitonic absorption peak of undistorted lead bromide perovskites with single layer is located around 400 nm.31 The great red-shift of the absorption peak of slightly distorted 1FP indicates a strong electronic coupling between inorganic sheets.


9


Page 10 of 20

Figure 4. (a) UV-vis (dashed line) and PL spectra (solid line, exc = 340 nm), (b) Tauc plot, (c) XPS-VB spectra and (d) the calculated band structure of 0FP, 1FP, 2FP and 3FP samples. (e) TRPL decay of 2FP probed at different wavelength. (f) TRPL decay of four F-substituted 2D LHPs samples probed at 437 nm, 453 nm, 409 nm and 415 nm for 0FP, 1FP, 2FP and 3FP, respectively.


10

Page 11 of 20 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


Table 1. Optical parameters of four prepared samples Bandgap

Bandgap

Bandgap

Excitonic Sample

absorption Eg

calculated from

calculated by

Tauc plot (eV)

DFT-PBE (eV)

absorption

(eV)

Excitonic PL

(Eg-PL)

peak (eV)

(meV)

0FP

3.28

3.12

2.93

2.59

3.10

180

1FP

3.12

2.89

2.72

2.37

2.89

230

2FP

3.39

3.21

3.04

2.71

3.20

190

3FP

3.33

3.14

2.98

2.66

3.12

210

Correspondingly, all four kinds of prepared LHPs samples present a broad band emission spanning the entire visible range (Figure 4a), attributed to the coupling between excitons and lattice. Note that a sharp emission peak denoted by a yellow dashed line is assigned to the excitonic emission, which matches well with the excitonic absorption. Owing to the large magnitude of distortion, 2FP shows the highest PL QY (~12.3%) among these four samples, which is also much higher than most reported 2D LHPs.15, 31-32 The PL QY values are ~ 4.0%, 0.2% and 3.2% for 0FP, 1FP and 3FP, respectively, indicating the significant role of lattice deformation on broad band emission. Tauc plot (Figure 4b) is depicted to indicate the bandgap of these series samples and the results are listed in Table 1. 0FP, 2FP and 3FP exhibit a similar bandgap ~3.0 eV, consistent with some (100) oriented 2D single layered LHPs.33-34 Unexpectedly, a bandgap of 2.72 eV is calculated for 1FP, which is, to our best knowledge, the lowest value observed for reported single-layered lead


11


Page 12 of 20

bromide perovskites. Because of the antibonding nature of the valance band (VB) of LHPs, octahedral tilting or lattice expansion will decrease the extent of Pb-Br overlap and lead to the falling of VB in energy.35 Since the conduction band (CB) is mainly derived from Pb 6p orbitals and close to nonbonding nature, the shift amount of CB is smaller than that of VB.35-36 Therefore, decreasing the magnitude of Pb-Br overlap will enlarge the bandgap. However, a reduced bandgap is observed for slightly distorted 1FP. This abnormal phenomenon indicates a strong interlayer electronic coupling due to the short interlayer distance, which dominates the reduction of bandgap.25 To determine the band alignment, X-ray photoelectron spectroscopy-valance band (XPS-VB) were conducted, as shown in Figure 4c and S2. The valance band offset was measured as 2.09, 1.72, 2.54 and 2.10 eV for 0FP, 1FP, 2FP and 3FP, respectively. The low density of state of 2FP is attributed to the weak interlayer electronic coupling and heavily distorted octahedron. The band structure and partial density of states (PDOS) of these series samples were also calculated using density functional theory (DFT-PBE) without spin-orbit coupling, as shown in Figure 4d and S3. The DFT-PBE calculations show that these four samples are all direct semiconductors. Since the calculated bandgaps of inorganic compounds are usually underestimated by using DFTPBE method,37 the calculated values show a deviation of ~0.35 eV compared to the values obtained from Tauc plot (Table 1), while the evolution of the simulated results match well with the experimental results. The PDOS diagrams of four prepared 2D LHPs show similar configuration, which are depicted in Figure S3. It is obvious that the states around the bandgap come from Br and Pb atoms without contribution from organic ligands for these four 2D LHPs, in according with the simulation results of 3D CsPbBr3.38 A strong hybridization between Pb s and Br p orbitals is observed in the valance band, while the conduction band is of nonbonding nature with contribution


12

Page 13 of 20 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


mainly from Pb p states. This result is in good agreement with the XPS-VB conclusion, in which the change of CB minimum is relatively small with respect to VB maximum. To understand the significant difference of white light emission in these four samples, timeresolved PL (TRPL) decay was conducted. Figure 4e shows that the PL lifetime decay of 2FP at different wavelengths. The emission from the red-shifted range exhibits a relatively longer average lifetime (Table S2), indicating the STE nature of the broadband emission.15, 39 The average PL lifetime of different F-substituted LHPs is also compared and shown in Figure 4f and Table S3. 2FP exhibits a much longer lifetime up to 7.77 ns than that of other three samples, suggesting a stronger and long-lasting coupling between excitons and lattice. Because of the marked disparity of the interlayer distance, the interlayer charge transfer is believed to behave differently for these four samples. Electrochemical techniques were conducted to gain deep insight into the charge transfer properties of the prepared samples. As shown in Figure 5a and b, great difference on the diameter of semiconductor is observed in the electrochemical impedance spectroscopy (EIS) for the four kinds of 2D LHPs. The EIS data were fitted with an equivalent circuit shown in the inset of Figure 5b and the fitting parameters were summarized in Table S4. R1, R2 and R3 are the series resistance, charge-transfer resistance inside the electrode and at the electrode/electrolyte interface, respectively. CPE1 and CPE2 are the constant phase elements, which model the double-layer capacitance at the interface of FTO/LHPs and LHPs/electrolyte. Apparently, all four prepared 2D LHPs show good photoconductivity properties based on the significant reduction of R2 and R3 under white light irradiation, However, 1FP exhibits much smaller charge-transfer resistance (6150 Ω), which is three orders of magnitude smaller than the resistance under dark. The markedly photoconductivity is attributed to both the smaller bandgap and shorter interlayer distance of 1FP, which enable a higher light absorption efficiency and


13


Page 14 of 20

stronger interlayer electronic coupling. This can be also verified by the transient photocurrent test (Figure 5c), in which 1FP shows a highest photocurrent of ~7.5 × 10-5 A/cm2 with the smallest thickness (Figure S4). In contrast with the other three samples, the shorter recovery time of 1FP manifests the faster charge transfer process at interface. Overall, these characterizations evidence that the small interlayer distance renders 1FP excellent interfacial charge transport.

Figure 5. EIS Nyquist plots of 0FP, 1FP, 2FP and 3FP obtained (a) in the dark and (b) under white light (100 mW/cm2) and (c) chronoamperometric i-t curve collected at -0.3 V vs Ag/AgCl, the area of working electrode is kept to be 1 cm2. Inset: the enlarged view of EIS (a and b) in the range of 0 < Z´ < 1000 Ω and the equivalent circuit (b).

The stability of LHPs is one of the critical factors that should be concerned before their commercialization. The air stability of prepared series samples has been studied as shown in Figure S5. Based on the XRD characterization, all F-substituted 2D LHPs show improved air stability in 150 h due to the hydrophobic nature of fluorinated alkyl ammonium fragments and strong hydrogen bonding network within the structures, indicating that F-substitution is an effective approach to further improve the air stability of 2D LHPs.


14

Page 15 of 20 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


In summary, intra- and intermolecular hydrogen bonding have been successfully constructed in three 2D single layered LHPs by fluorinating EA. The hydrogen bonding interaction has a significant effect on the configuration of organic ammonium ions located in the perovskite cavity, which results in great structural difference on interlayer distance and octahedral distortion, thereby varying the optical properties, band alignment, conductivity and stability of F-substituted EA layered LHPs. This study indicates the critical role of interlayer supramolecular interaction such as hydrogen bonding in determining the optoelectronic properties of 2D LHPs.

ASSOCIATED CONTENT Supporting Information Experimental methods, structural data, PDOS diagrams, SEM images and XRD pattern. CCDC number: 1938881 (2FP), 1938882 (3FP), 1938883 (1FP).

Notes The authors declare no competing financial interest.

ACKNOWLEDGEMENTS This project was supported by National Natural Science Foundation of China (NSFC: 51702205 and 21571122) and STU Scientific Research Foundation for Talents (NTF17001).


15


Page 16 of 20

REFERENCES (1).

Smith, M. D.; Connor, B. A.; Karunadasa, H. I. Tuning the Luminescence of Layered

Halide Perovskites. Chem. Rev. 2019, 119, 3104-3139. (2).

Katan, C.; Mercier, N.; Even, J. Quantum and Dielectric Confinement Effects in Lower-

Dimensional Hybrid Perovskite Semiconductors. Chem. Rev. 2019, 119, 3140-3192. (3).

Chen, S.; Shi, G. Two-Dimensional Materials for Halide Perovskite-Based Optoelectronic

Devices. Adv. Mater. 2017, 29, 1605448. (4).

Lin, H.; Zhou, C.; Tian, Y.; Siegrist, T.; Ma, B. Low-Dimensional Organometal Halide

Perovskites. ACS Energy Lett. 2017, 3, 54-62. (5).

Saidaminov, M. I.; Mohammed, O. F.; Bakr, O. M. Low-Dimensional-Networked Metal

Halide Perovskites: The Next Big Thing. ACS Energy Lett. 2017, 2, 889-896. (6).

Passarelli, J. V.; Fairfield, D. J.; Sather, N. A.; Hendricks, M. P.; Sai, H.; Stern, C. L.;

Stupp, S. I. Enhanced Out-of-Plane Conductivity and Photovoltaic Performance in n = 1 Layered Perovskites through Organic Cation Design. J. Am. Chem. Soc. 2018, 140, 7313-7323. (7).

Pedesseau, L.; Sapori, D.; Traore, B.; Robles, R.; Fang, H. H.; Loi, M. A.; Tsai, H.; Nie,

W.; Blancon, J. C.; Neukirch, A.; Tretiak, S.; Mohite, A. D.; Katan, C.; Even, J.; Kepenekian, M. Advances and Promises of Layered Halide Hybrid Perovskite Semiconductors. ACS Nano 2016, 10, 9776-9786. (8).

Chen, Y.; Sun, Y.; Peng, J.; Tang, J.; Zheng, K.; Liang, Z. 2D Ruddlesden-Popper

Perovskites for Optoelectronics. Adv. Mater. 2018, 30, 1703487. (9).

Luo, B.; Li, F.; Xu, K.; Guo, Y.; Liu, Y.; Xia, Z.; Zhang, J. Z. B-Site Doped Lead Halide

Perovskites: Synthesis, Band Engineering, Photophysics, and Light Emission Applications. J. Mater. Chem. C 2019, 7, 2781-2808.


16

Page 17 of 20 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


(10).

Li, Y.; Zhang, X.; Huang, H.; Kershaw, S. V.; Rogach, A. L. Advances in Metal Halide

Perovskite Nanocrystals: Synthetic Strategies, Growth Mechanisms, and Optoelectronic Applications. Materials Today 2019, DOI:10.1016/j.mattod.2019.06.007. (11).

Luo, B.; Naghadeh, S. B.; Zhang, J. Z. Lead Halide Perovskite Nanocrystals: Stability,

Surface Passivation, and Structural Control. ChemNanoMat 2017, 3, 456-465. (12).

Mao, L.; Stoumpos, C. C.; Kanatzidis, M. G. Two-Dimensional Hybrid Halide Perovskites:

Principles and Promises. J. Am. Chem. Soc. 2019, 141, 1171−1190. (13).

Cheng, Z.; Lin, J. Layered Organic–Inorganic Hybrid Perovskites: Structure, Optical

Properties, Film Preparation, Patterning and Templating Engineering. CrystEngComm 2010, 12, 2646. (14).

Straus, D. B.; Kagan, C. R. Electrons, Excitons, and Phonons in Two-Dimensional Hybrid

Perovskites: Connecting Structural, Optical, and Electronic Properties. J. Phys. Chem. Lett. 2018, 9, 1434-1447. (15).

Mao, L.; Wu, Y.; Stoumpos, C. C.; Wasielewski, M. R.; Kanatzidis, M. G. White-Light

Emission and Structural Distortion in New Corrugated Two-Dimensional Lead Bromide Perovskites. J. Am. Chem. Soc. 2017, 139, 5210-5215. (16).

Lemmerer, A.; Billing, D. G. Lead Halide Inorganic–Organic Hybrids Incorporating

Diammonium Cations. CrystEngComm 2012, 14 (6), 1954. (17).

Gan, L.; Li, J.; Fang, Z.; He, H.; Ye, Z. Effects of Organic Cation Length on Exciton

Recombination in Two-Dimensional Layered Lead Iodide Hybrid Perovskite Crystals. J. Phys. Chem. Lett. 2017, 8, 5177-5183. (18).

Yang, S.; Wu, D.; Gong, W.; Huang, Q.; Zhen, H.; Ling, Q.; Lin, Z. Highly Efficient

Room-Temperature Phosphorescence and Afterglow Fuminescence from Common Organic


17


Page 18 of 20

Fluorophores in 2D Hybrid Perovskites. Chem. Sci. 2018, 9, 8975-8981. (19).

Liu, L.; Deng, L.; Huang, S.; Zhang, P.; Linnros, J.; Zhong, H.; Sychugov, I.

Photodegradation of Organometal Hybrid Perovskite Nanocrystals: Clarifying the Role of Oxygen by Single-Dot Photoluminescence. J. Phys. Chem. Lett. 2019, 10, 864-869. (20).

Luo, B.; Pu, Y. C.; Lindley, S. A.; Yang, Y.; Lu, L.; Li, Y.; Li, X.; Zhang, J. Z. Organolead

Halide Perovskite Nanocrystals: Branched Capping Ligands Control Crystal Size and Stability. Angew. Chem. Int. Ed. 2016, 55, 8864-8868. (21).

Huang, H.; Chen, B.; Wang, Z.; Hung, T. F.; Susha, A. S.; Zhong, H.; Rogach, A. L. Water

Resistant CsPbX3 Nanocrystals Coated with Polyhedral Oligomeric Silsesquioxane and Their Use as Solid State Luminophores in All-perovskite White Light-Emitting Devices. Chem. Sci. 2016, 7, 5699-5703. (22).

Xuan, T.; Huang, J.; Liu, H.; Lou, S.; Cao, L.; Gan, W.; Liu, R.-S.; Wang, J. Super-

Hydrophobic Cesium Lead Halide Perovskite Quantum Dot-Polymer Composites with High Stability and Luminescent Efficiency for Wide Color Gamut White Light-Emitting Diodes. Chem. Mater. 2019, 31, 1042-1047. (23).

Tan, S.; Zhou, N.; Chen, Y.; Li, L.; Liu, G.; Liu, P.; Zhu, C.; Lu, J.; Sun, W.; Chen, Q.;

Zhou, H. Effect of High Dipole Moment Cation on Layered 2D Organic–Inorganic Halide Perovskite Solar Cells. Adv. Energy Mater. 2018, 1803024. (24).

Sebastien Sourisseau; Nicolas Louvain; Wenhua Bi; Nicolas Mercier; David Rondeau;

Florent Boucher; Jean-Yves Buzare´; Legein, C. Reduced Band Gap Hybrid Perovskites Resulting from Combined Hydrogen and Halogen Bonding at the Organic−Inorganic Interface. Chem. Mater. 2007, 19, 600-607. (25).

Nicolas Mercier; Sylvain Poiroux; Ame´de´e Riou; Batail, P. Unique Hydrogen Bonding


18

Page 19 of 20 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


Correlating with a Reduced Band Gap and Phase Transition in the Hybrid Perovskites (HO(CH2)2NH3)2PbX4 (X = I, Br). Inorg. Chem. 2004, 43, 8361-8366. (26).

Luo, B.; Guo, Y.; Li, X.; Xiao, Y.; Huang, X.; Zhang, J. Z. Efficient Trap-Mediated Mn2+

Dopant Emission in Two Dimensional Single-Layered Perovskite (CH3CH2NH3)2PbBr4. J. Phys. Chem. C 2019, 123, 14239-14245. (27).

Bernasconi, A.; Page, K.; Dai, Z.; Tan, L. Z.; Rappe, A. M.; Malavasi, L. Ubiquitous Short-

Range Distortion of Hybrid Perovskites and Hydrogen-Bonding Role: the MAPbCl3 Case. J. Phys. Chem. C 2018, 122, 28265-28272. (28).

Wang, X.; Meng, W.; Liao, W.; Wang, J.; Xiong, R. G.; Yan, Y. Atomistic Mechanism of

Broadband Emission in Metal Halide Perovskites. J. Phys. Chem. Lett. 2019, 10, 501-506. (29).

Smith, M. D.; Jaffe, A.; Dohner, E. R.; Lindenberg, A. M.; Karunadasa, H. I. Structural

Origins of Broadband Emission from Layered Pb-Br Hybrid Perovskites. Chem. Sci. 2017, 8, 4497-4504. (30).

Stoumpos, C. C.; Cao, D. H.; Clark, D. J.; Young, J.; Rondinelli, J. M.; Jang, J. I.; Hupp,

J. T.; Kanatzidis, M. G. Ruddlesden–Popper Hybrid Lead Iodide Perovskite 2D Homologous Semiconductors. Chem. Mater. 2016, 28, 2852-2867. (31).

Dohner, E. R.; Hoke, E. T.; Karunadasa, H. I. Self-Assembly of Broadband White-Light

Emitters. J. Am. Chem. Soc. 2014, 136, 1718-1721. (32).

Dohner, E. R.; Jaffe, A.; Bradshaw, L. R.; Karunadasa, H. I. Intrinsic White-Light

Emission from Layered Hybrid Perovskites. J. Am. Chem. Soc. 2014, 136 (38), 13154-13157. (33).

Biswas, A.; Bakthavatsalam, R.; Kundu, J. Efficient Exciton to Dopant Energy Transfer in

Mn2+-Doped (C4H9NH3)2PbBr4 Two-Dimensional (2D) Layered Perovskites. Chem. Mater. 2017, 29, 7816-7825.


19


(34).

Page 20 of 20

Yuan, Z.; Shu, Y.; Tian, Y.; Xin, Y.; Ma, B. A Facile One-Pot Synthesis of Deep Blue

Luminescent Lead Bromide Perovskite Microdisks. Chem. Commun. 2015, 51, 16385-16388. (35).

Prasanna, R.; Gold-Parker, A.; Leijtens, T.; Conings, B.; Babayigit, A.; Boyen, H. G.;

Toney, M. F.; McGehee, M. D. Band Gap Tuning via Lattice Contraction and Octahedral Tilting in Perovskite Materials for Photovoltaics. J. Am. Chem. Soc. 2017, 139, 11117-11124. (36).

Huang, H.; Bodnarchuk, M. I.; Kershaw, S. V.; Kovalenko, M. V.; Rogach, A. L. Lead

Halide Perovskite Nanocrystals in the Research Spotlight: Stability and Defect Tolerance. ACS Energy Lett. 2017, 2, 2071-2083. (37).

Zhou, J.; Li, M.; Ning, L.; Zhang, R.; Molokeev, M. S.; Zhao, J.; Yang, S.; Han, K.; Xia,

Z. Broad-Band Emission in a Zero-Dimensional Hybrid Organic [PbBr6] Trimer with Intrinsic Vacancies. J. Phys. Chem. Lett. 2019, 10, 1337-1341. (38).

Kang, J.; Wang, L. W. High Defect Tolerance in Lead Halide Perovskite CsPbBr3. J. Phys.

Chem. Lett. 2017, 8, 489-493. (39).

Hu, T.; Smith, M. D.; Dohner, E. R.; Sher, M. J.; Wu, X.; Trinh, M. T.; Fisher, A.; Corbett,

J.; Zhu, X. Y.; Karunadasa, H. I.; Lindenberg, A. M. Mechanism for Broadband White-Light Emission from Two-Dimensional (110) Hybrid Perovskites. J. Phys. Chem. Lett. 2016, 7, 22582263.


20

Fluorinated Spacers Regulate the Emission and Bandgap of Two

Recommend Documents