Abstract
Hybrid lead-halide perovskites have emerged as an excellent class of photovoltaic materials. Recent reports suggest that the organic molecular cation is responsible for local polar fluctuations that inhibit carrier recombination. We combine low-frequency Raman scattering with first-principles molecular dynamics (MD) to study the fundamental nature of these local polar fluctuations. Our observations of a strong central peak in the cubic phase of both hybrid (CH3NH3PbBr3) and all-inorganic (CsPbBr3) lead-halide perovskites show that anharmonic, local polar fluctuations are intrinsic to the general lead-halide perovskite structure, and not unique to the dipolar organic cation. MD simulations indicate that head-to-head Cs motion coupled to Br face expansion, occurring on a few hundred femtosecond time scale, drives the local polar fluctuations in CsPbBr3.
| Original language | English |
|---|---|
| Article number | 136001 |
| Number of pages | 6 |
| Journal | Physical Review Letters |
| Volume | 118 |
| Issue number | 13 |
| DOIs | |
| Publication status | Published - 31 Mar 2017 |
Funding
This work was supported by the U.S. Department of Energy (DOE), Office of Science, Office of Basic Energy Sciences, with funding at Columbia University through the Energy Frontier Research Center under Grant No. DE-SC0001085 and at SLAC National Accelerator Laboratory through the AMOS program within the Chemical Sciences, Geosciences, and Biosciences Division. O. Y. acknowledges funding by the FP7 People program under the project Marie Curie Grant No. IOF-622653. M. A. P. acknowledges support of the Brazilian Agencies CNPq and Fapemig. L. Z. T acknowledges support of the Office of Naval Research, under Grant No. N00014-14-1-0761. F. Z. acknowledges support of the DOE Office of BES, under Grant No. DE-FG02-07ER46431. A. M. R. acknowledges support of the Office of Naval Research, under Grant No. N00014-12-1-1033. L. K. and D. A. E. were supported by a research grant from Dana and Yossie Hollander, in the framework of the Weizmann Institute of Science (WIS) Alternative Sustainable Energy Research Initiative (AERI). D. A. E. further acknowledges financial support by the Austrian Science Fund (FWF), Grant No. J3608-N20. M. G. K. acknowledges funding from a DOE-NNSA grant and thanks the National Nuclear Security Administration for Grant No. DE-NA0002522. We thank Shi Liu for valuable discussions. O. Y. and Y. G. contributed equally to this work.
All Science Journal Classification (ASJC) codes
- General Physics and Astronomy