Thermal instability of organic-inorganic hybrid perovskites will be an inevitable hurdle for commercialization. Recently, all-inorganic cesium lead halide perovskites, in particular, CsPbI2Br, have emerged as thermally stable and efficient photovoltaic light absorbers. However, the fundamental properties of this material have not been studied in detail. The crystal formation behavior of CsPbI2Br is investigated by examining the surface morphology, crystal structure, and chemical state of the perovskite films. We discover a previously uncharacterized feature that the formation of black polymorph through optimal annealing temperature proves to be critical to both solar cell efficiency and phase stability. Our optimized planar heterojunction solar cell exhibits a J-V scan efficiency of 10.7% and open-circuit voltage of 1.23 V, which far outperforms the preceding literature.
Bibliographical noteFunding Information:
We gratefully acknowledge the support from National Research Foundation of Korea (NRF) grant funded by the Korea government (NRF-2016R1A2A1A05005216 NRF-2016M3D3A1A01913254, NRF-2015M2A2A6A01045277, NRF-2014M3A7B4051747). This work was also partially supported by the Korea Institute of Energy Technology Evaluation and Planning (KETEP) granted financial resource from the Ministry of Trade, Industry and Energy (MOTIE), Republic of Korea (20163010012450).
All Science Journal Classification (ASJC) codes
- Materials Science(all)
- Physical and Theoretical Chemistry