Ferroelectric Alignment of Organic Cations Inhibits Nonradiative

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Ferroelectic Alignment of Organic Cations Inhibits Non-Radiative Electron-Hole Recombination in Hybrid Perovskites: Ab Initio Non-Adiabatic Molecular Dynamics Joanna Jankowska, and Oleg V. Prezhdo J. Phys. Chem. Lett., Just Accepted Manuscript • DOI: 10.1021/acs.jpclett.7b00008 • Publication Date (Web): 01 Feb 2017 Downloaded from http://pubs.acs.org on February 2, 2017

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The Journal of Physical Chemistry Letters

Ferroelectic Alignment of Organic Cations Inhibits Non-Radiative Electron-Hole Recombination in Hybrid Perovskites: Ab Initio Non-Adiabatic Molecular Dynamics Joanna Jankowska∗,†,‡ and Oleg V. Prezhdo∗,‡ Institute of Physics, Polish Academy of Sciences, 02-668 Warsaw, Poland, and Department of Chemistry, University of Southern California, Los Angeles, CA 90089, USA E-mail: [email protected]; [email protected]

∗

To whom correspondence should be addressed Institute of Physics, Polish Academy of Sciences, 02-668 Warsaw, Poland ‡ Department of Chemistry, University of Southern California, Los Angeles, CA 90089, USA †

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Abstract Hybrid organic-inorganic perovskites show impressive potential for photovoltaic applications and currently give rise to one of the most vibrant research areas in the field. Until recently, the electrostatic interactions between their organic and inorganic components were considered mostly for stabilization of the fragile perovskite structure. We study the effect of local interactions of polar C-N bonds in the organic layer on the nonradiative electron-hole recombination in the recently reported room-temperature ferroelectric hybrid perovskite – (benzylammonium)2 PbCl4 . Using non-adiabatic molecular dynamics and real-time time-dependent density functional theory, we show that ferroelectric alignment of the polar groups weakens the electron-phonon non-adiabatic coupling and inhibits the non-radiative charge recombination. The effect is attributed to suppression of contributions of higher frequency phonons to the electron-phonon coupling. The coupling is dominated in the ferroelectric phase by slower collective motions. We also demonstrate the importance of van der Waals interactions for the charge-phonon relaxation in the hybrid perovskite systems. Combined with the longrange charge separation achievable in the ferroelectric phase, the weakened electronphonon coupling indicates that ferroelectric order in hybrid perovskites can lead to increased excited state lifetimes and improved solar energy conversion performance.

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Due to their numerous outstanding optical and electronic properties, hybrid organicinorganic perovskites (HOIP) are currently identified among the most promising materials for photovoltaic applications. In particular, hybrid perovskites stand out with their large light absorption coefficients, 1–3 long and balanced electron and hole diffusion lengths, 4–6 and high dielectric constants. 7–9 Furthermore, the bandgap (BG) in these materials is easily tunable through structural modifications, 10–14 spanning values from ultraviolet to near-infrared and, thus, allowing for almost perfect match with the desired optimum absorption range for the solar cells. 15,16 Apart from their excellent photophysical properties, hybrid perovskites attract much attention due to low cost of their production process. 17–19 All these features, being systematically improved since the initial recognition of hybrid perovskites as robust photovoltaic media, 20,21 contribute to the unprecedentedly rapid progress in the perovskitebased solar cells efficiency, which has been recently reported to reach 21.1% for a mixedcation material. 22 The ongoing material-research efforts towards the further enhancement of the perovskites performance cover number of issues, with the doping effects and material durability playing a prominent role. 23–30 Numerous thorough and up-to-date review articles are available on the subject. 9,31–35 In addition to the basic requirements usually raised for light-harvesting materials, one may consider other features which can enhance the overall photovoltaic performance, such as ferroelectricity of the active medium. 36,37 Macroscopic ferroelectric effects are known to support photoexcited charge carrier separation and are considered as possible origin for the observed switchable anomalous photovoltaic effect, in which the photogenerated voltage reaches values far beyond the bandgap limit. 9,37–39 Moreover, combining ferroelectricity and phototriggered electric response opens possibility for novel material applications, such as memory storage media, field effect transistors, etc. 40–44 This topic has been widely investigated for the purely inorganic perovskites. 45–49 Merging favorable photovoltaic and synthetic properties of hybrid perovskites with the ferroelectric effects has been thus recognized as a promising direction for future HOIP device development. An important step towards this goal, Liao et al.



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has recently reported synthesis of the first hybrid-perovskite room-temperature ferroelectric semiconductor. 50 The observed HOIP ferroelectricity is attributed to the relative orientation of polar C-N bonds in the material’s organic cation component. 50,51 Investigations in the field of HOIP materials cover a rich set of topics; however, up to now, electrostatic interactions between the organic and inorganic constituents in hybrid perovskites have been mostly considered in terms of stabilization of the perovskite structure. This stabilization is controlled through matching between the size of the organic linking group and the optimal shape of the inorganic framework. 33,52 Additionally, the extent of the organic molecule in the direction perpendicular to the inorganic plane controls dimensionality of the inorganic subsystem active in the photovoltaic process. 10,52,53 The newly observed highlyordered and stable ferroelectric orientation of the polar C-N bonds in HOIPs raises new questions for the possible role and impact of the interlayer interactions on the photovaltaic performance, especially since the C-N moiety acts as an universal linker to the inorganic framework in the hybrid perovkites family (with the formamidinium cation mentioned by the being a notable exception). Some very recent studies have been devoted to the polar group orientation effects on the basic HOIP photovoltaic properties, such as charge carriers interaction screening and separation 54–56 or possible dynamics changes of the BG character from direct to indirect. 57 Also, polar group reorientation effects on the thermal transport have been recently analyzed. 58 These latest emerging reports set up new direction in the perovskite properties studies, now placing the issue of organic-inorganic component interactions as one of the possible keys to understanding the preeminent photovoltaic properties of the hybrid perovskite family. In this letter, we apply ab initio non-adiabatic molecular dynamics (NAMD) to investigate the effect of the local electric order within the organic HOIP layer on the non-radiative hole-electron recombination rate, which has a strong influence on efficiencies of photovoltaic, photocatalytic and related devices. We demonstrate that electrostatic interactions between the organic and inorganic subsystems have a strong effect on the electron-phonon non-


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adiabatic coupling (NAC) and excited state lifetime. Ferroelectric arrangement of polar organic groups suppresses coupling of the electronic subsystem to higher-frequency phonons and inhibits the charge recombination. The suppressed charge-phonon interactions works hand-in-hand with the long-range effects, such as electron-hole separation and improved carriers mobility, 59–61 which altogether can lead to longer excited state lifetimes and improved solar cell performance. We also demonstrate the important role of the inclusion of dispersive van der Waals interactions in the studies on HOIP materials structural and electronic properties, and electron-vibrational dynamics. We focus on the room-temperature ferroelectric HOIP material proposed by Liao et al. 50 – (benzylammonium)2 PbCl4 , for its proved stable regular orientation of the polar C-N bonds, enabling unambiguous interpretation of the polar order effects. Our analysis starts with choice of model crystal cells to represent the experimentally observed ferro- and paraelectric phases. The ferroelectric phase (Fig. 1 a. and c.) has been modeled directly with a single crystal form, ferro, in which all polar C-N bonds are fully aligned and which was found the most energetically stable among other possible isomers. To map the paraelectric phase (Fig. 1 b. and d.), we choose two structures: the anti-ferro form with zero net electric dipole moment per crystal cell and mixed form in which the disordered paraelectric phase character is modeled through mixture of aligned and anti-aligned C-N bonds pairs. These forms were found to be less stable energetically than the ferro form by 0.16 and 0.09 eV, respectively. In all cases, the crystal cell includes two pairs of benzylammonium cations further duplicated according to the base-centered cell type (eight organic units altogether, with Pb4 Cl16 N8 C56 H80 total cell composition), thus allowing for characterization of nearestdipole-neighbor interactions. Fig. 2 illustrates total and atom-projected density of states calculated for the most stable ferro form. The data show that the top of the valence band is dominated by the halogen orbitals (of p character) and contributions from the organic cation (mostly p orbitals of the aromatic carbon atoms); at the same time, the bottom of the conduction band con-



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Figure 1: Structure of (benzylammonium)2 PbCl4 with its two phases exhibiting different electric properties: (a.) Ferroelectric Cmc2(1), and (b.) Paraelectric Cmca. Atomic color coding: grey – Pb, green – Cl, dark blue – N, orange – C, and turquoise – H. Dashed black octahedra highlight the lead-chlorine layer structure. Purple arrows in (a.) and green rectangles in (b.) indicate the aligned (ferroelectric) and disordered (paraelectric) C-N bonds orientations responsible for the total material dipole moment. Panels (c.) and (d.) show top view of the crystal cells chosen to model the two phases. (c) Structure representing the ferroelectric phase; (d) two structures representing the paralectric phase. Black dots mark the Pb atoms positions, and polygons illustrate the network of the in-plane Cl atoms occupying the polygons corners. Polygon color marks the micro-domain polarization: purple/green is used for ferroelectric/anti-ferroelectric dipole moment alignment, respectively. In addition, red and dark-blue arrows show the dipole moment orientation for the upper and lower organic layers. Black dashed-line squares mark the bc-plane cross-section of the unit cell.


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sists predominantly of the Pb s orbital functions. A similar picture, staying in line with typically observed HOIP patterns, has been found for the paraelectric forms: the corresponding figures have been included in the Supporting Information (SI, Fig. S1). HOMO and LUMO orbitals calculated at the Γ k-point are shown as inset in Fig. 2. The active space for the NAMD simulations consisted of these two orbitals, HOMO and LUMO, as they correspond to the lowest-energy hole-electron pair configuration and since the recently reported photogenerated-charge cooling timescales calculated for a similar system were found to lie in an ultrafast sub-picosecond regime, 62 much faster than the expected hole-electron recombination dynamics. This effect, together with the direct BG character of the material reported by Liao et al., 50 justifies the limitation to the single k-point sampling of the Brillouin zone for the dynamics calculation. It should be also noted that the present study does not account for the spin-orbit coupling (SOC) effects, recognized to cause a down-shift of the lowest conduction-band states energies in HOIPs. 35,63,64 Instead, we use a scalar-relativistic DFT approach known for reproducing accurately interstate-energy differences, which are important in estimation of the non-adiabatic transition probabilities.

Figure 2: Total density of states (DOS) and projected DOS (pDOS) calculated for the ferro form: total DOS – black, Pd pDOS – red, Cl pDOS– green, and organic part pDOS – blue solid lines, respectively. The inset shows calculated charge-density isosurfaces for HOMO and LUMO orbitals.



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After thermal equilibration at room temperature (300 K), the 15 ps long NAMD simulations have been performed. The energy- and time-related results of the simulation are summarized in Table 1. The canonically averaged BG values shown in the first column concentrate around 3.50 eV for the all three forms of the perovskite; in particular, the 3.56 eV value for the ferro form matches very well the experimentally measured 3.65 eV bandgap. The pure-dephasing times indicate ultrafast decoherence effects (≤ 10 fs) and also remain comparable in all cases. The main quantities of interest, the calculated recombination times (τ ), reveal an increasing trend in the anti-ferro → mixed → ferro sequence: thus, structures representing the paraelectric phase, anti-ferro and mixed, exhibit faster electron-hole recombination than the fully-ordered ferro structure. This difference in charge recombination dynamics stays in line with a tendency observed for mean electron-phonon NAC. In order to gain understanding of physical nature of the observed phenomenon, one needs to take a deeper look at the dynamics-related properties of the system, standing behind the NAC value. Table 1: Canonically averaged bandgap and its standard deviation (σBG ), absolute value of NAC, pure-dephasing time, and non-radiative electron-hole recombination time (τ ) for studied perovskite forms. Form

Bandgap / eV ferro 3.56 anti-ferro 3.37 mixed 3.41

σBG / meV 0.13 0.11 0.10

|NAC| / meV 0.658 0.849 0.768

Dephasing / fs 7.5 8.0 10.0

τ / ps 800 559 612

In Fig. 3 one can see a correlation relation between BG and NAC absolute value, plotted for the all three forms. While the data obtained for anti-ferro and mixed show relatively narrow BG energies distribution with NAC modulus reaching loosely the 3 meV range, the most-ordered ferro form shows higher BG with a long but sparse tail of low-energy values and truncated NAC distribution, limited to 2 meV. A combination of smaller coupling and larger gap observed for ferro favors slower relaxation. On the contrary, thermal fluctuations that decrease the energy gap and simultaneously increase the NAC provide the most important 8 ACS Paragon Plus Environment

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contribution to the non-radiative relaxation pathway, enhancing the relaxation rate in antiferro and mixed.

Figure 3: Correlation plot of BG vs. NAC absolute value for all studied forms; ferro – black, anti-ferro – red, and mixed – green. In order to obtain further insights into the electron-phonon coupling, we report the power spectra, Fig. 4, calculated as Fourier transforms of the autocorrelation functions of the BG oscillations. Again, we observe similarity between the paraelectric anti-ferro and mixed forms, which differ from the ferro structure. Specifically, in the ordered ferro case the vibration frequencies having the highest impact on the bandgap energy are concentrated in the lowest energy region: frequencies below 100 cm−1 contribute 72% to the overall integratedspectrum intensity, mostly corresponding to polar C-N group rocking in the direction parallel to the inorganic plane. The high intensity indicates strong impact on the BG oscillations and is responsible for the observed fast dephasing (see Table 1). At the same time, in the disordered phases, anti-ferro and mixed, we observe much smaller intensity of the low-energy peaks (48% and 55% integrated intensity below 100 cm−1 , respectively), with visible contributions from the higher-frequency phonons, explaining the higher mean NAC value observed for the anti-ferro and mixed forms. The explicit relative intensities of peaks lying in the low-energy part of the spectrum are shown in Table S1 in the SI. It should be also stressed that in the course of our study we witnessed a fundamental role of the van der Waals interactions inclusion for a proper description of the electronic structure response to the nuclei dynamics. Without this correction one arrives with a noticeably 9 ACS Paragon Plus Environment


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different NAMD results, showing much weaker response of the flexible organic component to the inorganic layer vibrations; therefore the NAC distribution, and power spectrum shape are also strongly affected. For comparison, we show the uncorrected results in the SI (Table S2 and Figs. S2-S3).

Figure 4: Power spectra (continuous solid lines) and low-energy IR vibrational spectra (vertical ticks) for all studied forms: ferro – black, anti-ferro – red and mixed – green. The gray ticks in the background mark energetic positions of all modes calculated for particular form, regardless if they are IR-active or not. In summary, we used state-of-the-art ab initio non-adiabatic molecular dynamics simulations to model how local electric order in a ferroelectric HOIP material affects the holeelectron recombination. For our study, we chose the (benzylammonium)2 PbCl4 material, for which a room-temperature stable ferroelectric phase was reported recently. We found that the ferroelectric phase exhibits slower electron-hole recombination than the crystal forms representing the paraelectric phase. To understand the reasons, we considered in detail the key electronic structure features and their dynamic characteristics. We established that, despite similar bandgaps and pDOS spectra of all forms, the electron-phonon NAC distributions are notably different. In particular, the higher NAC value tail is missing in 10 ACS Paragon Plus Environment

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the ferroelectric phase. This observation underlines the crucial role of dynamics effects in identification and understanding of the material features that influence the electron-hole recombination process. The difference of the ferroelectric phase from the other structures finds further manifestation in the electron-phonon power spectrum. The ferroelectric order suppresses electronic coupling to higher frequency modes. The suppression is responsible for the lower NAC values and slower recombination dynamics. Finally, in the course of the investigation, we identified the essential role of the inclusion of dispersive van der Waals interactions, not only for the structural and electronic properties of HOIP materials, but also for the electron-phonon dynamics. The reported study generates important insights into the fundamental mechanisms responsible for charge recombination and loss of photovoltaic efficiency in hybrid organic-inorganic perovskites. Combined with the long-range charge separation and improved carrier mobilities expected in ferroelectric systems, the suppressed electron-hole recombination acts further to extend excited state lifetimes and enhance solar energy conversion efficiencies. Though the reported study focuses on a single perovskite system, (benzylammonium)2 PbCl4 , the uncovered difference between the ordered and disordered phases should be generic, due to the universal presence of the polar C-N moiety in the HOIP family of compounds and the general importance of lower frequency collective vibrational motions in ordered ferroelectric systems. Computational Methods. We employ the plane-wave density functional theory approach, as implemented in Quantum Espresso program package, 65 to describe the electronic properties of the hybrid perovskite system. The crystal structure parameters and initial atomic coordinates have been taken from Ref.; 66 the latter have been further re-optimized. For the optimized structure coordinates please refer to Tables S2-S4 in the SI. For all electronic calculations we used the Perdew-Burke-Ernzerhof (PBE) exchange-correlation functional with ultrasoft pseudopotential including nonlinear-core and scalar-relativistic corrections, the Grimme’s DFT-D2 dispersion correction was also applied. 67,68 The basis set energy cutoff was set to 60 Ry. For the structural optimization, molecular dynamics and DOS calcu-



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lations an uniform Monkhorst-Pack mesh of 6 × 6 × 6 k-points was used, while in other cases (NAC and NAMD) the calculations comprised the Γ-point only. The chosen approach, despite possible limitations arising from restricted k- (electrons) and q- (phonons) momentum space sampling, 69 has been considered a method of choice for the aimed NAMD analysis due to its affordability and innate capability of explicit treatment of the anharmonic effects, expected to play an important role in the studied system. 58,70,71 Following a 500 fs thermalization dynamics at 300 K performed under the Andersen thermostat conditions, 3.1 ps microcanonical trajectories were generated and used to sample initial conditions for the extended 15 ps non-adiabatic dynamics study with a timestep set to 1 fs (the molecular parameters acquired during the 3.1 ps simulation were repeated periodically). The NAMD calculation was performed using the decoherence induced surface hopping approach (DISH), 72 implemented with the PYXAID code 73,74 under the classical path approximation. The non-adiabatic effects have been averaged over 1000 trajectories, each of them involving 1000 realizations of the stochastic surface hopping process, in order to achieve high quality timescale estimations. The non-radiative electron-hole recombination timescales (τ ) have been obtained from an exponential fit to the population change, in its short-time approximation: exp (−t/τ ) ≈ 1−t/τ . The integration of the power spectra covered frequency region up to 500 cm−1 . The atomic structure and orbital visualizations have been obtained with XCrysDen software. 75

Acknowledgement JJ thanks the Kosciuszko Foundation for generous support through the Kosciuszko Foundation Grant for young researchers. OVP acknowledges support of the USA National Science Foundation, grant CHE-1565704.


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References (1) Wolf, S. D.; Holovsky, J.; Moon, S.-J.; Lper, P.; Niesen, B.; Ledinsky, M.; Haug, F.-J.; Yum, J.-H.; Ballif, C. Organometallic Halide Perovskites: Sharp Optical Absorption Edge and Its Relation to Photovoltaic Performance. J. Phys. Chem. Lett. 2014, 5, 1035–1039. (2) Kim, H.-S.; Lee, J.-W.; Yantara, N.; Boix, P. P.; Kulkarni, S. A.; Mhaisalkar, S.; Grätzel, M.; Park, N.-G. High Efficiency Solid-State Sensitized Solar Cell-Based on Submicrometer Rutile TiO2 Nanorod and CH3NH3PbI3 Perovskite Sensitizer. Nano Lett. 2013, 13, 2412–2417. (3) Yin, W. J.; Shi, T.; Yan, Y. Unique properties of halide perovskites as possible origins of the superior solar cell performance. Adv. Mater. 2014, 26, 4653–4658. (4) Stranks, S. D.; Eperon, G. E.; Grancini, G.; Menelaou, C.; Alcocer, M. J. P.; Leijtens, T.; Herz, L. M.; Petrozza, A.; Snaith, H. J. Electron-Hole Diffusion Lengths Exceeding 1 Micrometer in an Organometal Trihalide Perovskite Absorber. Science 2014, 342, 341–344. (5) Piatkowski, P.; Cohen, B.; Ponseca, C. S.; Salado, M.; Kazim, S.; Ahmad, S.; Sundström, V.; Douhal, A. Unraveling Charge Carriers Generation, Diffusion, and Recombination in Formamidinium Lead Triiodide Perovskite Polycrystalline Thin Film. J. Phys. Chem. Lett. 2016, 7, 204–210. (6) Piatkowski, P.; Cohen, B.; Ramos, J. F.; Di Nunzio, M. R.; Mohammad K., N.; Grätzel, M.; Ahmad, S. Direct Monitoring of Ultrafast Electron and Hole Dynamics in Perovskite Solar Cells. Phys. Chem. Chem. Phys. 2015, 17, 14674–14684. (7) Juarez-Perez, E.; Sanchez, R.; Badia, L.; Garcia-Belmonte, G.; Kang, Y.; Mora-Sero, I.; Bisquert, J. Photoinduced giant dielectric constant in lead halide perovskite solar cells. J. Phys. Chem. Lett. 2014, 5, 2390–2394. 13 ACS Paragon Plus Environment


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

(8) Lin, Q.; Armin, A.; Nagiri, R. C. R.; Burn, P. L.; Meredith, P. Electro-optics of perovskite solar cells. Nat. Photonics 2014, 9, 106–112. (9) Fan, Z.; Sun, K.; Wang, J. Perovskites for photovoltaics: a combined review of organicinorganic halide perovskites and ferroelectric oxide perovskites. J. Mater. Chem. A 2015, 3, 18809–18828. (10) Papavassiliou, G. C.; Koutselas, I. B. Structural, optical and related properties of some natural three- and lower-dimensional semiconductor systems. Synthetic Metals 1995, 71, 1713–1714, Proceedings of the International Conference on Science and Technology of Synthetic Metals (ICSM ’94). (11) Noh, J. H.; Im, S. H.; Heo, J. H.; Mandal, T. N.; Seok, S. I. Chemical Management for Colorful, Efficient, and Stable InorganicOrganic Hybrid Nanostructured Solar Cells. Nano Lett. 2013, 13, 1764–1769. (12) Amat, A.; Mosconi, E.; Ronca, E.; Quarti, C.; Umari, P.; Nazeeruddin, M. K.; Grätzel, M.; Angelis, F. D. Cation-Induced Band-Gap Tuning in Organohalide Perovskites: Interplay of SpinOrbit Coupling and Octahedra Tilting. Nano Lett. 2014, 14, 3608–3616. (13) Jacobsson, J. T.; Correa-Baena, J.-P.; Pazoki, M.; Saliba, M.; Schenk, K.; Grätzel, M.; Hagfeldt, A. Exploration of the compositional space for mixed lead halogen perovskites for high efficiency solar cells. Energy Environ. Sci. 2016, 9, 1706–1724. (14) Mittal, M.; Jana, A.; Sarkar, S.; Mahadevan, P.; Sapra, S. Size of the Organic Cation Tunes the Band Gap of Colloidal Organolead Bromide Perovskite Nanocrystals. J. Phys. Chem. Lett. 2016, 7, 3270–3277. (15) Shockley, W.; Queisser, H. J. Detailed Balance Limit of Efficiency of p-n Junction Solar Cells. J. Appl. Phys. 1961, 32, 510–519.


Page 14 of 22

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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


(16) Pellet, N.; Gao, P.; Gregori, G.; Yang, T. Y.; Nazeeruddin, M. K.; Maier, J.; Grätzel, M. Mixed-organic-cation perovskite photovoltaics for enhanced solar-light harvesting. Angew. Chemie - Int. Ed. 2014, 53, 3151–3157. (17) Mitzi, D. B.; Yuan, M.; Liu, W.; Kellock, A. J.; Chey, S. J.; Deline, V.; Schrott, A. G. A High-Efficiency Solution-Deposited Thin-Film Photovoltaic Device. Adv. Mater. 2008, 20, 3657–3662. (18) Todorov, T.; Mitzi, D. B. Direct Liquid Coating of Chalcopyrite Light-Absorbing Layers for Photovoltaic Devices. Eur. J. Inorg. Chem. 2010, 2010, 17–28. (19) Snaith, H. J. Perovskites : The Emergence of a New Era for Low-Cost , High-. J. Phys. Chem. Lett. 2013, 4, 3623–3630. (20) Mitzi, D. B.; Feild, C. A.; Harrison, W. T. A.; Guloy, A. M. Conducting tin halides with a layered organic-based perovskite structure. Nature 1994, 369, 467–469. (21) Kagan, C. R.; Mitzi, D. B.; Dimitrakopoulos, C. D. Organic-Inorganic Hybrid Materials as Semiconducting Channels in Thin-Film Field-Effect Transistors. Science 1999, 286, 945–947. (22) Saliba, M.; Matsui, T.; Seo, J.-Y.; Domanski, K.; Correa-Baena, J.-P.; Nazeeruddin, M. K.; Zakeeruddin, S. M.; Tress, W.; Abate, A.; Hagfeldt, A. et al. Cesiumcontaining triple cation perovskite solar cells: improved stability, reproducibility and high efficiency. Energy Environ. Sci. 2016, 9, 1989–1997. (23) Liu, J.; Prezhdo, O. V. Chlorine Doping Reduces Electron-Hole Recombination in Lead Iodide Perovskites: Time-Domain Ab Initio Analysis. J. Phys. Chem. Lett. 2015, 6, 4463–4469. (24) Long, R.; Liu, J.; Prezhdo, O. V. Unravelling the Effects of Grain Boundary and Chem-



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ical Doping on Electron-Hole Recombination in CH3NH3PbI3 Perovskite by TimeDomain Atomistic Simulation. J. Am. Chem. Soc. 2016, 138, 3884–3890. (25) Edri, E.; Kirmayer, S.; Kulbak, M.; Hodes, G.; Cahen, D. Chloride Inclusion and Hole Transport Material Doping to Improve Methyl Ammonium Lead Bromide PerovskiteBased High Open-Circuit Voltage Solar Cells. J. Phys. Chem. Lett. 2014, 5, 429–433. (26) Wang, J. T.-W.; Wang, Z.; Pathak, S. K.; Zhang, W.; DeQuilettes, D.; Wisnivesky, F.; Huang, J.; Nayak, P.; Patel, J.; hanis Yusof, et al. Efficient Perovskite Solar Cells by Metal Ion Doping. Energy Environ. Sci. 2016, 9, 2892–2901. (27) Long, R.; Fang, W.-H.; Prezhdo, O. V. Moderate Humidity Delays Electron-Hole Recombination in Hybrid Organic-Inorganic Perovskites: Time-Domain Ab Initio Simulations Rationalize Experiments. J. Phys. Chem. Lett. 2016, 3215–3222. (28) Tong, C.-J.; Geng, W.; Tang, Z.-K.; Yam, C.-Y.; Fan, X.-L.; Liu, J.; Lau, W.-M.; Liu, L.-M. Uncovering the Veil of the Degradation in Perovskite CH3NH3PbI3 upon Humidity Exposure: A First-Principles Study. J. of Phys. Chem. Lett. 2015, 6, 3289– 3295. (29) Lee, J. W.; Kim, D. H.; Kim, H. S.; Seo, S. W.; Cho, S. M.; Park, N. G. Formamidinium and cesium hybridization for photo- and moisture-stable perovskite solar cell. Adv. Energy Mater. 2015, 5 . (30) Wang, F.; Geng, W.; Zhou, Y.; Fang, H.-H.; Tong, C.-J.; Loi, M. A.; Liu, L.-M.; Zhao, N. Phenylalkylamine Passivation of Organolead Halide Perovskites Enabling High-Efficiency and Air-Stable Photovoltaic Cells. Adv. Mater. 2016, 28, 9986–9992. (31) Brenner, T. M.; Egger, D. a.; Kronik, L.; Hodes, G.; Cahen, D. Hybrid organic-inorganic perovskites: low-cost semiconductors with intriguing charge-transport properties. Nat. Rev. Mater. 2016, 1, 15007–15023.


Page 16 of 22

Page 17 of 22

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


(32) Seo, J.; Noh, J. H.; Seok, S. I. Rational Strategies for Efficient Perovskite Solar Cells. Acc. Chem. Res. 2016, 49, 562–572. (33) Chen, Q.; Marco, N. D.; Michael, Y.; Song, T.-b.; Chen, C.-c.; Zhao, H. Under the spotlight : The organic inorganic hybrid halide perovskite for optoelectronic applications. Nano Today 2015, 10, 355–396. (34) Berry, J.; Buonassisi, T.; Egger, D. A.; Hodes, G.; Kronik, L.; Loo, Y. L.; Lubomirsky, I.; Marder, S. R.; Mastai, Y.; Miller, J. S. et al. Hybrid Organic-Inorganic Perovskites (HOIPs): Opportunities and Challenges. Adv. Mater. 2015, 27, 5102–5112. (35) Pedesseau, L.; Sapori, D.; Traore, B.; Robles, R.; Fang, H. H.; Loi, M. A.; Tsai, H.; Nie, W.; Blancon, J. C.; Neukirch, A. et al. Advances and Promises of Layered Halide Hybrid Perovskite Semiconductors. ACS Nano 2016, 10, 9776–9786. (36) Yuan, Y.; Xiao, Z.; Yang, B.; Huang, J. Arising applications of ferroelectric materials in photovoltaic devices. J. Mater. Chem. A 2014, 2, 6027–6041. (37) Butler, K.; Frost, J.; Walsh, A. Ferroelectric materials for solar energy conversion: photoferroics revisited. Energy Environ. Sci. 2015, 8, 838–848. (38) Fridkin, V. M.; Popov, B. Anomalous photovoltaic effect in ferroelectrics. Uspekhi Fiz. Nauk 1978, 126, 657–671. (39) Yang, S. Y.; Seidel, J.; Byrnes, S. J.; Shafer, P.; Yang, C.-H.; Rossell, M. D.; Yu, P.; Chu, Y.-H.; Scott, J. F.; Ager, J. W. et al. Above-bandgap voltages from ferroelectric photovoltaic devices. Nat. Nanotechnol. 2010, 5, 143–147. (40) Gan, B. K.; Yao, K.; Lai, S. C.; Chen, Y. F.; Goh, P. C. An ultraviolet (UV) detector using a ferroelectric thin film with in-plane polarization. IEEE Electron Device Lett. 2008, 29, 1215–1217.



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

(41) Guo, R.; You, L.; Zhou, Y.; Lim, Z. S.; Zou, X.; Chen, L.; Ramesh, R.; Wang, J. Nonvolatile memory based on the ferroelectric photovoltaic effect. Nat. Commun. 2013, 4, 1990. (42) Hu, Z.; Tian, M.; Nysten, B.; Jonas, A. M. Regular arrays of highly ordered ferroelectric polymer nanostructures for non-volatile low-voltage memories. Nat. Mater. 2009, 8, 62–67. (43) Lee, D.; Yang, S. M.; Kim, T. H.; Jeon, B. C.; Kim, Y. S.; Yoon, J. G.; Lee, H. N.; Baek, S. H.; Eom, C. B.; Noh, T. W. Multilevel data storage memory using deterministic polarization control. Adv. Mater. 2012, 24, 402–406. (44) Scott, J. F. Applications of modern ferroelectrics. Science 2007, 315, 954–959. (45) Cohen, R. E. Origin of ferroelectricity in perovskite oxides. Nature 1992, 358, 136–138. (46) Bhattacharya, K.; Ravichandran, G. Ferroelectric perovskites for electromechanical actuation. Acta Mater. 2003, 51, 5941–5960. (47) Nuraje, N.; Su, K. Perovskite ferroelectric nanomaterials. Nanoscale 2013, 5, 8752–80. (48) Grinberg, I.; West, D. V.; Torres, M.; Gou, G.; Stein, D. M.; Wu, L.; Chen, G.; Gallo, E. M.; Akbashev, A. R.; Davies, P. K. et al. Perovskite oxides for visible-lightabsorbing ferroelectric and photovoltaic materials. Nature 2013, 503, 509–12. (49) Saidi, W. A.; Martirez, J. M. P.; Rappe, A. M. Strong Reciprocal Interaction between Polarization and Surface Stoichiometry in Oxide Ferroelectrics. Nano Lett. 2014, 14, 6711–6717. (50) Liao, W.-Q.; Zhang, Y.; Hu, C.-L.; Mao, J.-G.; Ye, H.-Y.; Li, P.-F.; Huang, S. D.; Xiong, R.-G. A lead-halide perovskite molecular ferroelectric semiconductor. Nat. Commun. 2015, 6, 7338.


Page 18 of 22

Page 19 of 22

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


(51) Stroppa, A.; Quarti, C.; De Angelis, F.; Picozzi, S. Ferroelectric Polarization of CH3NH3PbI3: A Detailed Study Based on Density Functional Theory and Symmetry Mode Analysis. J. Phys. Chem. Lett. 2015, 2223–2231. (52) Mitzi, D. B. Templating and structural engineering in organic-inorganic perovskites. J. Chem. Soc. Dalt. Trans. 2001, 1–12. (53) Quan, L. N.; Yuan, M.; Comin, R.; Voznyy, O.; Beauregard, E. M.; Hoogland, S.; Buin, A.; Kirmani, A. R.; Zhao, K.; Amassian, A. et al. Ligand-Stabilized ReducedDimensionality Perovskites. J. Am. Chem. Soc. 2016, 138, 2649–2655. (54) Ma, J.; Wang, L.-W. Nanoscale Charge Localization Induced by Random Orientations of Organic Molecules in Hybrid Perovskite CH3NH3PbI3. Nano Lett. 2015, 15, 248– 253. (55) Nie, W.; Blancon, J.; Neukirch, A. J.; Appavoo, K.; Tsai, H.; Chhowalla, M.; Alam, M. A.; Sfeir, M. Y.; Katan, C.; Even, J. et al. Light-activated photocurrent degradation and self-healing in perovskite solar cells. Nat. Commun. (in Press.) 2016, 7, 1–9. (56) Neukirch, A. J.; Nie, W.; Blancon, J.-C.; Appavoo, K.; Tsai, H.; Sfeir, M. Y.; Katan, C.; Pedesseau, L.; Even, J.; Crochet, J. J. et al. Polaron Stabilization by Cooperative Lattice Distortion and Cation Rotations in Hybrid Perovskite Materials. Nano Lett. 2016, 16, 3809–3816. (57) Motta, C.; El-Mellouhi, F.; Kais, S.; Tabet, N.; Alharbi, F.; Sanvito, S. Revealing the role of organic cations in hybrid halide perovskite CH3NH3PbI3. Nat. Commun. 2015, 6, 7026. (58) Hata, T.; Giorgi, G.; Yamashita, K. The effects of the organic-inorganic interactions on the thermal transport properties of CH 3 NH 3 PbI 3. Nano Lett. 2016, 2749–2753.



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 20 of 22

(59) Frost, J. M.; Butler, K. T.; Brivio, F.; Hendon, C. H.; van Schilfgaarde, M.; Walsh, A. Atomistic origins of high-performanc1. Frost, J. M. et al. Atomistic origins of highperformance in hybrid halide perovskite solar cells. Nano Lett. 14, 258490 (2014).e in hybrid halide perovskite solar cells. Nano Lett. 2014, 14, 2584–90. (60) Liu, S.; Zheng, F.; Koocher, N. Z.; Takenaka, H.; Wang, F.; Rappe, A. M. Ferroelectric Domain Wall Induced Band Gap Reduction and Charge Separation in Organometal Halide Perovskites. J. Phys. Chem. Lett. 2015, 6, 693–699. (61) Pecchia, A.; Gentilini, D.; Rossi, D.; Auf Der Maur, M.; Di Carlo, A. Role of Ferroelectric Nanodomains in the Transport Properties of Perovskite Solar Cells. Nano Lett. 2016, 16, 988–992. (62) Madjet, M. E.-A. E.-A.; Akimov, A.; El-Mellouhi, F.; Berdiyorov, G.; Ashhab, S.; Tabet, N.; Kais, S. Enhancing the Carrier Thermalization Time in Organometallic Perovskites by Halide Mixing. Phys. Chem. Chem. Phys. 2016, 18, 5219–5231. (63) Even, J.; Pedesseau, L.; Jancu, J.-M.; Katan, C. Importance of SpinOrbit Coupling in Hybrid Organic/Inorganic Perovskites for Photovoltaic Applications. J. Phys. Chem. Lett. 2013, 4, 2999–3005. (64) Quarti, C.; Mosconi, E.; De Angelis, F. Structural and electronic properties of organohalide hybrid perovskites from ab initio molecular dynamics. Phys. Chem. Chem. Phys. 2015, 17, 9394–9409. (65) Giannozzi, P.; Baroni, S.; Bonini, N.; Calandra, M.; Car, R.; Cavazzoni, C.; Ceresoli, D.; Chiarotti, G. L.; Cococcioni, M.; Dabo, I. et al. QUANTUM ESPRESSO: a modular and open-source software project for quantum simulations of materials. J. Phys.:Condens. Matter 2009, 21, 395502. (66) Bhattacharya, R.;

Sinha, M.;

Dey, R.;

Righi, L.;


Bocelli, G.;

Ghosh, A.

Page 21 of 22

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


Synthesis,

crystal

structure

and

thermochromism

of

benzimidazolium

tetrachlorocuprate:(C7 H7 N2 )2 [CuCl4 ]. Polyhedron 2002, 21, 2561–2565. (67) Grimme, S. Semiempirical GGA-type density functional constructed with a long-range dispersion correction. J. Comput. Chem. 2006, 27, 1787–1799. (68) Barone, V.; Casarin, M.; Forrer, D.; Pavone, M.; Sambi, M.; Vittadini, A. Role and effective treatment of dispersive forces in materials: Polyethylene and graphite crystals as test cases. J. Comput. Chem. 2009, 30, 934–939. (69) Giustino, F.; Cohen, M.; Louie, S. Electron-phonon interaction using Wannier functions. Phys. Rev. B 2007, 76, 1–19. (70) Brivio, F.; Frost, J. M.; Skelton, J. M.; Jackson, A. J.; Weber, O. J.; Weller, M. T.; Go˜ ni, A. R.; Leguy, A. M. A.; Barnes, P. R. F.; Walsh, A. Lattice dynamics and vibrational spectra of the orthorhombic, tetragonal, and cubic phases of methylammonium lead iodide. Phys. Rev. B - Condens. Matter Mater. Phys. 2015, 92, 1–8. (71) Mosconi, E.; Quarti, C.; Ivanovska, T.; Ruani, G.; De Angelis, F. Structural and electronic properties of organo-halide lead perovskites: a combined IR-spectroscopy and ab initio molecular dynamics investigation. Phys. Chem. Chem. Phys. 2014, 16, 16137– 16144. (72) Jaeger, H. M.; Fischer, S.; Prezhdo, O. V. Decoherence-induced surface hopping. J. Chem. Phys. 2012, 137, 22A545. (73) Akimov, A. V.; Prezhdo, O. V. The PYXAID Program for Non-Adiabatic Molecular Dynamics in Condensed Matter Systems. J. Chem. Theory Comput. 2013, 9, 4959– 4972. (74) Akimov, A. V.; Prezhdo, O. V. Advanced capabilities of the PYXAID program: Inte-



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

gration schemes, decoherence effects, multiexcitonic states, and field-matter interaction. J. Chem. Theory Comput. 2014, 10, 789–804. (75) Kokalj, A. Computer graphics and graphical user interfaces as tools in simulations of matter at the atomic scale. Comp. Mater. Sci. 2003, 28, 155–168.


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Ferroelectric Alignment of Organic Cations Inhibits Nonradiative

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