title: Spatially Non-uniform Trap State Densities in Solution-Processed Hybrid Perovskite Thin Films.
abstract: The facile solution-processability of methylammonium lead halide (CH3NH3PbI3) perovskites has catalyzed the development of inexpensive, hybrid perovskite-based optoelectronics. It is apparent, though, that solution-processed CH3NH3PbI3 films possess local emission heterogeneities, stemming from electronic disorder in the material. Herein we investigate the spatially resolved emission properties of CH3NH3PbI3 thin films through detailed emission intensity versus excitation intensity measurements. These studies enable us to establish the existence of nonuniform trap density variations wherein regions of CH3NH3PbI3 films exhibit effective free carrier recombination while others exhibit emission dynamics strongly influenced by the presence of trap states. Such trap density variations lead to spatially varying emission quantum yields and correspondingly impact the performance of both methylammonium lead halide perovskite solar cells and other hybrid perovskite-based devices. Of additional note is that the observed spatial extent of the optical disorder extends over length scales greater than that of underlying crystalline domains, suggesting the existence of other factors, beyond grain boundary-related nonradiative recombination channels, which lead to significant intrafilm optical heterogeneities.
authors: Department of Chemistry and Biochemistry, University of Notre Dame , Notre Dame, Indiana 46556, United States.
authors: Sergiu
authors: S
authors: Draguta
authors: Department of Chemistry and Biochemistry, University of Notre Dame , Notre Dame, Indiana 46556, United States.|Nanotechnology Engineering, University of Waterloo , Waterloo, Ontario N2L 3G1, Canada.
authors: Siddharatha
authors: S
authors: Thakur
authors: Department of Chemistry and Biochemistry, University of Notre Dame , Notre Dame, Indiana 46556, United States.
authors: Yurii V
authors: YV
authors: Morozov
authors: Department of Chemistry and Biochemistry, University of Notre Dame , Notre Dame, Indiana 46556, United States.
authors: Yuanxing
authors: Y
authors: Wang
authors: Department of Chemical and Biomolecular Engineering, University of Notre Dame , Notre Dame, Indiana 46556, United States.|Radiation Laboratory, University of Notre Dame , Notre Dame, Indiana 46556, United States.
authors: Joseph S
authors: JS
authors: Manser
authors: Department of Chemistry and Biochemistry, University of Notre Dame , Notre Dame, Indiana 46556, United States.|Department of Chemical and Biomolecular Engineering, University of Notre Dame , Notre Dame, Indiana 46556, United States.|Radiation Laboratory, University of Notre Dame , Notre Dame, Indiana 46556, United States.
authors: Prashant V
authors: PV
authors: Kamat
authors: Department of Chemistry and Biochemistry, University of Notre Dame , Notre Dame, Indiana 46556, United States.
authors: Masaru
authors: M
authors: Kuno