Atomic-Scale Tailoring of Organic Cation of Layered Ruddlesden

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Chemical and Dynamical Processes in Solution; Polymers, Glasses, and Soft Matter

Atomic-Scale Tailoring Organic Cation of Layered Ruddlesden-Popper Perovskite Compounds Han Pan, Xiaojuan Zhao, Xiu Gong, Yan Shen, and Mingkui Wang J. Phys. Chem. Lett., Just Accepted Manuscript • DOI: 10.1021/acs.jpclett.9b00479 • Publication Date (Web): 01 Apr 2019 Downloaded from http://pubs.acs.org on April 1, 2019

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The Journal of Physical Chemistry Letters

Atomic-Scale Tailoring Organic Cation of Layered Ruddlesden-Popper Perovskite Compounds Han Pan a, Xiaojuan Zhao a, Xiu Gong a, Yan Shen a, and Mingkui Wang a,*

a

Wuhan National Laboratory for Optoelectronics, School of Optical and Electronic

Information, Huazhong University of Science and Technology, Wuhan 430074, Hubei, P. R. China KEYWORDS: two-dimensional perovskite; electron-withdrawing groups; red shift； exciton-binding energy; crystal orientation; photovoltaic

1

ACS Paragon Plus Environment

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ABSTRACT: Layered Ruddlesden-Popper (RP) phase perovskite compounds have emerged as one of promising photovoltaic materials for solar cell application, but they suffer from poor absorption and strong exciton-binding energy. Herein, fluoro-, chloro-, and bromosubstitution on the 4-position of phenyl group in the component C6H5CH2CH2NH3+ (PEA+) are designed and synthesized to investigate their effect on the layered RP type H-PEA2MA2Pb3I10 (MA=CH3NH3) perovskite as a protocol. Single crystal X-ray diffraction

and

temperature-dependent

photoluminescence

spectroscopy

characterization revel the electron-withdrawing halogen in organic cations decreases the distortion of inorganic sheets and significantly reduces the impact of twodimensional quantum and dielectric confinement. This is further verified with an increased visible absorption and lower exciton-binding energy for these new layered RP type perovskite compounds. A planar structured perovskite solar cells using FPEA2MA2Pb3I10 layer achieves a power conversion efficiency of 5.8%, which is better than the reference H-PEA2MA2Pb3I10.

Table of Contents:

2


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Solar cells based on layered organic-inorganic hybrid lead halide perovskites have achieved rapid progress because of high stability, especially humidity resistance.1-4 The layered Ruddlesden-Popper (RP) phase perovskite holds a general formula of An−1A’2BnX3n+1, where A is CH3NH3+ (MA+) or HN2CHNH2+ (FA+), A’ is a large aliphatic or aromatic ammonium cation, B is a divalent metal cation such as Pb2+, X is a typical halide anion, and n represents the number of [BX6]4− octahedral inorganic layers.5,6 These inorganic layers are separated by organic hydrophobic bulky cations A’, and thus effectively block water erosion. Unfortunately, compared with the threedimensional counterparts, the layered perovskite compounds have shown less effective light absorption property.7,8 This is because a self-organized formation of multiquantum-well electronic structure of layered perovskites leads to the blue-shift of absorption due to quantum confinement effect.9 Meanwhile a synergistic effect of twodimensional quantum and dielectric confinement significantly increases the excitonbinding energy.10,11 Although tailoring the integer n can principally adequate light absorption and decrease the exciton-binding energy,

12,13

usually this approach

inevitably sacrifices solar cell device stability.14,15 The cations of n-CH3CH2CH2CH2NH3+ (BA+) and C6H5CH2CH2NH3+ (H-PEA+) are widely utilized as organic moieties in the layered RP perovskite studies. Compared with BA+, the H-PEA+ processes a larger high-frequency-dielectric constant due to its aromatic ring, which reduces the effect of the dielectric confinement and further decreases the exciton-binding energy.16,17 In this study, we designed and synthesized the functional phenyl components by substitution the element on the 4-position in the prototypical H-PEA+ cation with fluoro-, chloro-, and bromo- group to investigate the effect of electron-withdrawing groups on the RP phase H-PEA2MA2Pb3I10 perovskite. Specifically, those new components for RP phase perovskite compounds are noted as 2-phenylethanaminium (H-PEA+), 2-(4-fluorophenyl) ethanaminium (F-PEA+), 2-(4chlorophenyl) ethanaminium (Cl-PEA+), and 2-(4-bromophenyl) ethanaminium (BrPEA+). We find the absorption edge of X-PEA2MA2Pb3I10 (X=F, Cl, Br) red-shift relative to that of H-PEA2MA2Pb3I10. The electron-withdrawing halogen groups in organic cations contribute to reducing the impact of quantum and dielectric 3



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confinement, and to lowering exciton-binding energy. Under a standard testing condition a higher power conversion efficiency of 5.8% can be achieved for the device based on F-PEA2MA2Pb3I10 RP phase perovskite compound absorber than that of the H-PEA2MA2Pb3I10 control reference. Furthermore, an increased crystallinity and outplane crystal growth was observed in the F-PEA2MA2Pb3I10 perovskite compound active layer. The equilibrium geometry at ground state in air with density functional theory was first carried out with Spartan 16 with ωB97X-D/6-31G* to gain insight into the structure-property relationship of these new materials. The energy levels of H-PEA+, F-PEA+, Cl-PEA+, and Br-PEA+ were evaluated to be -11.84 eV, -11.66 eV, -11.52 eV, and -11.32 eV (versus vacuum) for the HOMO, and -2.05 eV, -2.12 eV, -2.15 eV, and -2.15 eV (versus vacuum) for the LUMO, respectively. Clearly, the principal effect of halide substituent (F, Cl, and Br) onto the proton in these phenethylamines pushes the LUMO energy level downwards and the HOMO energy level upwards. This finally narrows the HOMO-LUMO energy gap, which benefits reduction of the confinement potential for quantum well.16 Likewise, the dipole moment was evaluated to be ~13.16 D for F-PEA+, ~13.49 D for Cl-PEA+, and ~13.34 D for Br-PEA+ respectively, being larger than that of the reference H-PEA+ (11.83D). These can be correlated with the fact that the elemental F, Cl, and Br with high electronegative (χ: 3.98, 3.16 and 2.96, respectively) are more prone to withdraw electrons compared to the H (χ: 2.10) in these components. The strong push-pull electron capability brings in high dipole moment for organic cations might be contributed to the intramolecular charge transport. The dipole moment of a molecule reflects its polarity. The cations of large polar spacer are known to reduce dielectric confinement in the layered RP perovskite compounds.17 Therefore, the cations X-PEA+ (X=F, Cl, Br) could hopefully reduce the exciton-binding energy and thus are further expected for exciton dissociation in the layered perovskites. Encouraged by aforementioned results, the substituted PEA2MA2Pb3I10 RP phase perovskite thin films (abbreviated as H-PEA, F-PEA, Cl-PEA, and Br-PEA, respectively) were fabricated by a one-step spin-coating method (see supporting information for details). Fourier transform infrared (FTIR) transmission spectra of the 4


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Figure 1. GIWAXS measurements of (a) H-PEA and (b) F-PEA. Out-of-plane XRD patterns of spin-coated films of (c) H-PEA and (d) F-PEA with (e) the illustration of respective diffraction planes.

H-PEA, and X-PEA(X=F, Cl, Br) films were measured to determine the existence of F, Cl, and Br in the resulted X-PEA(X=F, Cl, Br) films, as shown in Figure S2a. The strong peak observed at 1219 cm−1 can be ascribed to the C-F stretching vibration in the F-PEA film, while the peak at 632 cm−1 belong to the C-Cl stretching vibration in the Cl-PEA film and at 606 cm−1 belong to the C-Br stretching vibration in the Br-PEA film.31 These confirm the present of substituent groups in the resulted films. X-ray diffraction (XRD) measurements were used to investigate the effect of electron5



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withdrawing group on the crystal phase and crystallinity of layered perovskites. The clear peaks around 14° and 28° in the XRD patterns corresponding to the (111) and (222) planes of the samples indicate a vertical growth of the crystal compound (Figure S2b).12,18 The (0k0) reﬂection peak at low diffraction angle (2θ Cl-PEA > Br-PEA. 6,12 These might be derived from hydrogen and fluorine with smaller covalent radius (32 pm and 64 pm, respectively) compared with chlorine and bromine (values being 99 pm and 114 pm, respectively). This would result in a high proportion of a preferential orientation. Grazing incident wide-angle X-ray scattering (GIWAXS) measurements were carried out to further analyze the crystal orientation and crystalline quality in the H-PEA and F-PEA perovskites films. Figure 1a and 1b compares the GIWAXS patterns of these two cases and the corresponding intensity versus q (where q is the scattering vector (q = 4π sin(θ)/λ). The position of reﬂection peaks are almost the same, which consists with the result of XRD. Moreover, figure 1c and 1d present the out-plane XRD patterns of H-PEA and F-PEA films from GIWAXS measurements. A wide XRD pattern at about 14° found in this study could be caused by too thick film or a wide distribution of Xray wavelength, and this has been observed in other reports.32 Clearly, the peak intensity for the (111) plane is larger than that of the (020) plane for the F-PEA film. This is opposite for the H-PEA films. This result indicates fluoro-substitution induces a preferential orientation in the RP phase perovskite film on substrates. Two additional secondary diffraction with peaks 2θ at 6.6° corresponding to the (040) plane and 28.6° corresponding to the (222) plane was observed in the F-PEA films. This demonstrates an increased crystallinity in the sample. Figure 1e clearly illustrates the respective diffraction planes in the F-PEA films. Moreover, figure S2c shows the full width at half-maximum (FWHM) of four samples for the diffraction peaks of (111) plane. The FWHM of the F-PEA, Cl-PEA, and Br-PEA is 0.257°, 0.194°, and 0.185°, respectively, narrower than that of the H-PEA (0.296°). The decreased FWHM indicates the high 6


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crystallinity. The increased crystallinity of the F-PEA film might derive from the interaction between the fluorine and the hydrogen in adjacent benzene rings through hydrogen bonds which could promote an interaction of organic cations in layer spaces. The effect of electron-withdrawing group on the optical properties of layered perovskites was further investigated with UV-vis absorption spectroscopy and steadystate photoluminescence (PL) spectroscopy measurements. All the samples were spincoated on plasma-cleaned glass substrates. Figure S3 depicts the top surface scanning electron microscope (SEM) images for four samples. It can be seen that all of the perovskite films are smooth, dense and pore-free morphology. In comparison to the pristine H-PEA film with the absorption onset at ca. 730 nm, the X-PEA (X=F, Cl, Br) films exhibited red-shift with the absorption onset at ca. 771 nm, 776 nm and 780 nm (Figure S4). In addition, after excited at 532 nm, the four sample showed a strong emission peak (Figure 2a) in the visible range, which gradually shifts from 725 nm for H-PEA, to 757 nm, 762 nm, and 764 nm for F-PEA, Cl-PEA, and Br-PEA perovskite films, respectively. This is fully consistent with their absorption characteristic. For the RP phase perovskite materials, the inorganic network framework determines the band gaps, while the organic cations play the role on optical properties via their affect onto the inorganic [BX6]4− octahedral layers.19 We further synthesized X-PEA2PbI4 (X=F, Cl, Br) single crystals to study the impact of organic cations on inorganic layer. Specifically, the angle α of Pb-I-Pb, which is directly related to the optical properties of the layered RP perovskites,20,21 was selected to determine the most immediate impact

Figure 2. (a) Steady-state PL spectra of H-PEA and X-PEA (X=F, Cl, Br) RP perovskite films on the glass substrates. (b) Schematic representation of X-PEA2PbI4 structure with Pb-I-Pb angle (α) and intramolecular hydrogen bonding. (C) Energy band alignment of the H-PEA and X-PEA (X=F, Cl, Br)-based perovskite solar cells. 7



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of NH3(CH2CH2+-) on the inorganic sheets. A large angle α means the diminished effect of the organic cation on the inorganic sheets. 29The angle α (Figure 2b) was estimated to be 151.3° for H-PEA2PbI430, 152.9° for F-PEA2PbI4, 153.6° for Cl-PEA2PbI4, and 152.6° for Br-PEA2PbI4, respectively. This result strongly verifies that a substitution of electron-withdrawing component at the 4-position on phenyl group can significantly reduce the distortion of inorganic sheets and weaken the electrostatic interaction among them. F, Cl and Br have an impact on benzene ring: electron donation by conjugation and electron withdrawal by induction, but the latter is even more dramatic. Therefore, there is a significant interaction between NH3(CH2CH2+-) as the hydrogen bond donor and the aromatic ring with the 4-position substituent as a hydrogen bond acceptor. The strong effect can be proved by a shortened distance between N(H3CH2CH2+-) and C (in benzene ring and bonding to CH2CH2NH3) as shown in Figure 2b indicated with a double sided arrow, where F-PEA2PbI4, Cl-PEA2PbI4 and Br-PEA2PbI4 are 2.972 Å, 2.959 Å, and 2.976 Å, respectively, compared with the reference of H-PEA2PbI4 being 2.989Å. Besides, from the single crystal X-ray diffraction of F-PEA2PbI4, the distance of the fluorine and the hydrogen in adjacent benzene rings is about 2.7 Å within the range of hydrogen bonds, which would facilitate the interaction of organic cations in layer spaces. Moreover, the reduction of electrostatic interaction between the positively charged NH3(CH2CH2-) and negatively charged [PbX6]4- lattice can be evidenced by an increased valence-band maximum (VBM) of RP phase perovskites due to the disturbance of the antibonding hybrid state of Pb s and I p orbitals in the octahedral network by cations.23, 24 The VBM of H-PEA2PbI4 and X-PEA2PbI4 (X= F, Cl, Br) were evaluated to be 5.90 eV, 5.81 eV, 5.72 eV and 5.72 eV through ultraviolet photoelectron spectroscopy characterization (Figure 2c and Figure S5). To explore the impact of electron-withdrawing group on the exciton-binding energy of the RP phase perovskites, we measured the stable-state photoluminescence spectrum of the perovskite films under different temperatures (80-280K). The temperaturedependent PL peak wavelength is shown in Figure 3a. We find all of the phase transition point in the temperature region around 160K according to the shift of the PL peak wavelength,

which

is

consistent

with

the

orthorhombic-tetragonal

phase 8


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Figure 3. (a) Temperature-dependent PL peak wavelength on temperature of H-PEA and X-PEA (X=F, Cl, Br). The temperature-dependent integrated PL intensity on 1/T of (b) H-PEA and FPEA and (c) Cl-PEA and Br-PEA perovskite films on glass substrates. Error bars indicate the error from peak fitting. (d) Statistics of exciton-binding energy of 20 films made up of H-PEA or XPEA (X= F, Cl, Br). 9



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transition temperature of MAPbI3.22 The same phase transition temperature probably comes from the same composition of inorganic sheets. Furthermore, we calculated the exciton-binding energy (Eb) of 20 films made up of H-PEA or X-PEA (X= F, Cl, Br) by fitting the temperature-dependent PL spectra above 160 K (Figure 3b, 3c and 3d) with following equation since the tetragonal phase is stable above 160 K,

I (T) 

I0 E 1+A exp( b ) kbT

(1)

where I0 is the PL intensity extrapolated at 0 K, A is a constant, Eb is the binding energy, and kb is the Boltzmann constant.25 The average Eb of H-PEA and X-PEA (X= F, Cl, Br) approximately were evaluated to be 144.8 meV, 114.5 meV, 117.6 meV, and 123.7 meV, respectively. Clearly, the incorporation of electron-withdrawing groups plays an important role in the decrease of the exciton-binding energy, which stems from reducing the impact of 2D quantum and dielectric confinement. Figure 4a and 4b present the time-resolved photoluminescence (TRPL) decay spectra of H-PEA and F-PEA films and Cl-PEA and Br-PEA films, respectively, deposited on nonconductive glass. A bi-exponential decay model was used to fit the TRPL data and the results are list in Table S3. The shorter lifetime (τ1) is attributed to trap state components and the longer lifetime (τ2) to the bulk carrier recombination.26,27 We used the longer carrier lifetime for comparison. Obviously, the lifetime of 31.60 ns for the pristine film was prolonged to 72.00 ns for the F-PEA, 50.12 ns for the Cl-PEA,

Figure 4. PL decay profiles of (a) H-PEA and F-PEA and (b) Cl-PEA and Br-PEA perovskites on the glass substrate. 10


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and 43.58 ns for the Br-PEA, which are ascribed to the decrease of the exciton-binding energy.17 The hole and electron mobility of these samples were evaluated with spacecharge-limited current method as shown in Table 1 and Figure S6. The device structures were

FTO/NiOx/perovskites/spiro-OMeTAD/Au

for

hole-only

devices

and

FTO/SnO2/perovskites/PC61BM/BCP/Ag for electron-only devices. Interestingly, we find the charge carrier mobility has been increased by the fluoro- and chlorosubstitution on the 4-position of phenyl group in PEA+ of the RP phase perovskite thin films. Apparently, the F-PEA possesses the highest electron mobility (μe) of 2.84×10-4 cm2 V−1 s−1 and hole mobility (μh) of 3.02×10-4 cm2 V−1 s−1, partly owing to its improved Table 1. Charge carrier motilities of H-PEA and X-PEA (X=F, Cl, Br) perovskite films measured by the SCLC method. Device

μe (cm2 V-1s-1)

μh (cm2 V-1s-1)

μe /μh

HPEA

0.61×10-4

0.84×10-4

0.72

FPEA

2.84×10-4

3.02×10-4

0.94

ClPEA

1.08×10-4

1.33×10-4

0.81

BrPEA

0.47×10-4

0.66×10-5

7.12

crystallinity compared with H-PEA and an ordered orientation compared with Cl-PEA and Br-PEA. Besides, the ratio of μe to μh for the F- PEA (0.94) is the closest to 1 among the four samples. More balanced electron and hole mobility could contribute to charge collection and restrain recombination.29 Solar cells were fabricated with a configuration of FTO/NiOx/H-PEA2MA2Pb3I10 or X-PEA2MA2Pb3I10 (X=F, Cl, Br)/PC61BM/BCP/Ag and measured under a simulated AM 1.5 G illumination. Figure 5 shows the corresponding photocurrent density-voltage (J-V) curves of the PVSCs. The F-PEA device exhibited the highest power conversion efficiency (PCE) of 5.83% with short-circuit current density (Jsc) of 8.64 mA∙cm−2, open circuit voltage (Voc) of 1.09 V and fill factor (FF) of 61.9%. The H-PEA device showed a PCE of 3.06% with Jsc of 5.66mA∙cm−2, Voc of 1.10V and FF of 49.4%. The enhancement of efficiency for the F-PEA device could be attributed to the higher of Jsc 11



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Figure 5. J-V curves of H-PEA and X-PEA (X=F, Cl, Br) perovskite devices under AM 1.5G 1 sun (100 mW∙cm

−2)

illumination with 10 mV voltage steps and 40 ms delay time in a reverse scan

direction.

and FF. The Cl-PEA device showed a PCE of 3.91% with Jsc of 6.63 mA∙cm−2, Voc of 1.03V and FF of 57.1%. The Br-PEA device exhibited a PCE of 2.03% with Jsc of 4.07 mA∙cm−2, Voc of 0.96V and FF of 51.9%. Compared with the F-PEA, the poor photovoltaic performance of the Cl-PEA and Br-PEA probably derives from the parallel crystalline growth which is unsuited to photovoltaic applications due to the severe disturbance of charge migration. The response of the X-PEA (X=F, Cl, Br) to photons also extended to longer wavelength compared with that of the H-PEA (left coordinate, Figure S7), which is in line with the absorption spectrum, respectively. Besides, the integrated photocurrents from IPCE measurements closely match the JSC values from the J−V curve (right coordinate, Figure S7). This study introduces electron-withdrawing groups into organic cations to enhance absorption and reduce exciton-binding energy, which furtherly improve the PCE of layer RP perovskite solar cells. For concept-in-proof, atomic fluoro-, chloro-, and bromosubstitution on the 4-position of phenyl group in PEA+ are designed and synthesized for RP phase H-PEA2MA2Pb3I10 perovskite as a protocol. We have shown that a reducing disturbance to inorganic framework by such substituents could narrow 12


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the bandgaps of perovskite films. In addition, the obtained perovskites possess lower exciton-binding energies due to a reduction of 2D quantum and dielectric confinement effect. The planar structured perovskite solar cell using F-PEA2MA2Pb3I10 RP perovskite layer have attained a PCE of 5.8%, showing over 90% enhancement comparing to the H-PEA2MA2Pb3I10 control reference. On the basis of these findings, we believe that the appropriate choice of electron-withdrawing substituents in atomic scale might provide an alternative way to tailor the photovoltaic performance of layered perovskite solar cells. This control is given by modifying the structure and interaction of inorganic sheets through hydrogen bonding and steric effect by the impact of electron-withdrawing substituents. Furthermore, organic cations with functional groups or steric effect will offer the diverse of the optical and electronic properties of RP perovskites, which could be expected to provide more possibilities for RP perovskites in greater application areas and prospects. ASSOCIATED CONTENT Supporting Information 1 The Supporting Information is available free of charge on the ACS Publications website at http://pubs.acs.org. Experimental section, fabrication process, crystallographic details, characterization with SEM, UPS and photoelectronic properties Supporting Information 2 X-ray crystallographic data for FPEA2PbI4 (CIF) Supporting Information 3 X-ray crystallographic data for ClPEA2PbI4 (CIF) Supporting Information 4 X-ray crystallographic data for BrPEA2PbI4 (CIF) AUTHOR INFORMATION Corresponding Authors *E-mail: [email protected] (M.W.). Author Contributions These authors contributed equally to this work 13



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Notes The authors declare no competing financial interest. ACKNOWLEDGMENTS Financial support from the Natural Science Foundation of China (No. 21673091), t the NSFC Major International (Regional) Joint Research Project NSFC-SNSF (No. 51661135023), the Central Universities of Huazhong University of Science & Technology (2018KFYXKJC034), and the Double fist-class research funding of ChinaEU Institute for Clean and Renewable Energy (3011187029). The authors thank the Analytical and Testing Centre of Huazhong University of Science & Technology for the measurements of the samples.

REFERENCES (1) Proppe, A. H.; Quintero-Bermudez, R.; Tan, H.; Voznyy, O.; Kelley, S. O.; Sargent, E. H. Synthetic Control over Quantum Well Width Distribution and Carrier Migration in LowDimensional Perovskite Photovoltaics. J. Am. Chem. Soc. 2018, 140, 2890-2896. (2) Yan, L.; Hu, J.; Guo, Z.; Chen, H.; Toney, M. F.; Moran, A. M.; You, W.

General Post-

annealing Method Enables High-Efficiency Two-Dimensional Perovskite Solar Cells. ACS Appl. Mater. Interfaces 2018, 10, 33187-33197. (3) Li, Y.; Milic, J. V.; Ummadisingu, A.; Seo, J. Y.; Im, J. H.; Kim, H. S.; Liu, Y.; Dar, M. I.; Zakeeruddin, S. M.; Wang, P.; Hagfeldt, A.; Gratzel, M. Bifunctional Organic Spacers for Formamidinium-Based Hybrid Dion-Jacobson Two-Dimensional Perovskite Solar Cells. Nano Lett. 2019, 19, 150–157. (4) Ahmad, S.; Fu, P.; Yu, S.; Yang, Q.; Liu, X.; Wang, X.; Wang, X.; Guo, X.; Li, C. DionJacobson Phase 2D Layered Perovskites for Solar Cells with Ultrahigh Stability. Joule 2019, 3, 794-806 (5) Yao, K.; Wang, X.; Xu, Y.-X.; Li, F. ; Zhou, L. Multilayered perovskite materials based on polymeric-ammonium cations for stable large-area solar cell. Chem. Mater 2016, 28, 31313138. (6) Lai, H.; Kan, B.; Liu, T.; Zheng, N.; Xie, Z.; Zhou, T.; Wan, X.; Zhang, X.; Liu, Y.; Chen, Y. Two-Dimensional Ruddlesden-Popper Perovskite with Nanorod-like Morphology for Solar 14


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Cells with Efficiency Exceeding 15%. J. Am. Chem. Soc. 2018, 140, 11639-11646. (7) Smith, I. C.; Hoke, E. T.; Solis-Ibarra, D.; McGehee, M. D.; Karunadasa, H. I. A layered hybrid perovskite solar-cell absorber with enhanced moisture stability. Angew. Chem., Int. Ed. 2014, 126, 11414 –11417. (8) Tanaka, K.; Kondo, T. Bandgap and exciton binding energies in lead-iodide-based natural quantum-well crystals. Sci. Technol. Adv. Mater. 2004, 4, 599-604. (9) Mudd, G. W.; Svatek, S. A.; Ren, T.; Patane, A.; Makarovsky, O.; Eaves, L.; Beton, P. H.; Kovalyuk, Z. D.; Lashkarev, G. V.; Kudrynskyi, Z. R.; Dmitriev, A. I. Tuning the bandgap of exfoliated InSe nanosheets by quantum confinement. Adv. Mater. 2013, 25, 5714–5718. (10) Kitazawa, N. Excitons in two-dimensional layered perovskite compounds: (C6H5CH4NH3)2 Pb(Br,I)4 and (C6H5C2H4NH3)2Pb(Cl,Br)4. Mater. Sci. Eng., B 1997, 49, 233-238. (11) Mitzi, D. B.; Chondroudis, K.; Kagan, C. R. Design, Structure, and Optical Properties of Organic-Inorganic Perovskites Containing an Oligothiophene Chromophore. Inorg. Chem. 1999, 38, 6246-6256. (12) Cao, D. H.; Stoumpos, C. C.; Farha, O. K.; Hupp, J. T.; Kanatzidis, M. G. 2D Homologous Perovskites as Light-Absorbing Materials for Solar Cell Applications. J. Am. Chem. Soc. 2015, 137, 7843-7850. (13) Quan, L. N.; Yuan, M.; Comin, R.; Voznyy, O.; Beauregard, E. M.; Hoogland, S.; Buin, A.; Kirmani, A. R.; Zhao, K.; Amassian, A.; Kim, D. H.; Sargent, E. H. Ligand-Stabilized Reduced-Dimensionality Perovskites. J. Am. Chem. Soc. 2016, 138, 2649-2655. (14) Liao, Y.; Liu, H.; Zhou, W.; Yang, D.; Shang, Y.; Shi, Z.; Li, B.; Jiang, X.; Zhang, L.; Quan, L. N.; Quintero-Bermudez, R.; Sutherland, B. R.; Mi, Q.; Sargent, E. H.; Ning, Z. Highly Oriented Low-Dimensional Tin Halide Perovskites with Enhanced Stability and Photovoltaic Performance. J. Am. Chem. Soc. 2017, 139, 6693-6699. (15) Hong, X.; Ishihara, T.; Nurmikko, A. V. Dielectric confinement effect on excitons inPbI4-based layered semiconductors. Phys. Rev. B 1992, 45, 6961-6964. (16) Even, J.; Pedesseau, L.; Katan, C. Understanding quantum confinement of charge carriers in layered 2D hybrid perovskites. ChemPhysChem 2014, 15, 3733-3741. (17) Cheng, B.; Li, T.-Y.; Maity, P.; Wei, P.-C.; Nordlund, D.; Ho, K.-T.; Lien, D.-H.; Lin, C.-H.; Liang, R.-Z.; Miao, X.; Ajia, I. A.; Yin, J.; Sokaras, D.; Javey, A.; Roqan, I. S.; Mohammed, 15



Page 16 of 17

O. F.; He, J.-H. Extremely reduced dielectric confinement in two-dimensional hybrid perovskites with large polar organics. Commun. Phys.2018, 1:80. (18) Zhang, X.; Wu, G.; Yang, S.; Fu, W.; Zhang, Z.; Chen, C.; Liu, W.; Yan, J.; Yang, W.; Chen, H. Vertically Oriented 2D Layered Perovskite Solar Cells with Enhanced Efficiency and Good Stability. Small 2017, 13, 1700611. (19) Zhang, S.-F.; Chen, X.-K.; Ren, A.-M.; Li, H.; Bredas, J.-L. Impact of Organic Spacers on the Carrier Dynamics in 2D Hybrid Lead-Halide Perovskites. ACS Energy Lett. 2018, 4, 17-25. (20) Knutson J. L.; Martin J. D.; Mitzi D. B. Tuning the band gap in hybrid tin iodide perovskite semiconductors using structural templating. Inorg. Chem. 2005, 44, 4699-4705. (21) Xu, Z.; Mitzi, D. B.; Dimitrakopoulos, C. D.; Maxcy, K. R. Semiconducting perovskites (2XC6H4C2H4NH3)2SnI4 (X = F, Cl, Br): steric interaction between the organic and inorganic layers. Inorg. Chem. 2003, 42, 2031-2039. (22) Milot, R. L.; Eperon, G. E.; Snaith, H. J.; Johnston, M. B.; Herz, L. M. Temperature-Dependent Charge-Carrier Dynamics in CH3NH3PbI3 Perovskite Thin Films. Adv. Funct. Mater. 2015, 25, 6218-6227. (23) Matsuishi, K.; Ishihara, T.; Onari, S.; Chang, Y. H.; Park, C. H. Optical properties and structural phase transitions of lead-halide based inorganic–organic 3D and 2D perovskite semiconductors under high pressure. Phys. Status Solidi B 2004, 241, 3328-3333. (24) Lang, L.; Yang, J.-H.; Liu, H.-R.; Xiang, H. J.; Gong, X. G. First-principles study on the electronic and optical properties of cubic ABX3 halide perovskites. Phys. Lett. A 2014, 378, 290-293. (25) Wei, Y.; Li, M.; Li, R.; Zhang, L.; Yang, R.; Zou, W.; Cao, Y.; Xu, M.; Yi, C.; Wang, N.; Wang, J.; Huang, W. Efficient charge separation at multiple quantum well perovskite/PCBM interface. Appl. Phys. Lett. 2018, 113, 041103. (26) 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. 2019, 9, 1803024. (27) Li, H.; Lu, J.; Zhang, T.; Shen, Y.; Wang, M. Cation-Assisted Restraint of a Wide Quantum Well and Interfacial Charge Accumulation in Two-Dimensional Perovskites. ACS Energy Lett. 2018, 3, 1815-1823. 16


Page 17 of 17 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) Zhou, N.; Shen, Y.; Li, L.; Tan, S.; Liu, N.; Zheng, G.; Chen, Q.; Zhou, H. Exploration of Crystallization Kinetics in Quasi Two-Dimensional Perovskite and High Performance Solar Cells. J. Am. Chem. Soc. 2018, 140, 459-465. (29) Zhang, X.; Wu, G.; Fu, W.; Qin, M.; Yang, W.; Yan, J.; Zhang, Z.; Lu, X.; Chen, H. Orientation Regulation of Phenylethylammonium Cation Based 2D Perovskite Solar Cell with Efficiency Higher Than 11%. Adv. Energy Mater. 2018, 8, 1702498. (30) Billing, D. G. Acta Cryst. 2002, E58, m669-m671. (31) Simons,W. W. The Sadtler handbook of infrared spectra. Sadtler Research Laboratories, 1978. (32) Zhang, X.; Munir, R.; Xu, Z.; Liu, Y.; Tsai, H.; Nie, W.; Li, J.; Niu, T.; Smilgies, D. M.; Kanatzidis, M. G. Phase Transition Control for High Performance Ruddlesden-Popper Perovskite Solar Cells. Adv. Mater. 2018, 30, e1707166

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Atomic-Scale Tailoring of Organic Cation of Layered Ruddlesden

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