Preserving the stability of Sn-based halide perovskites is a primary concern in developing photovoltaic light-absorbing materials for lead-free perovskite solar cells. Whereas the addition of SnX2 (X = F, Cl, Br) has been demonstrated to improve the photovoltaic performance of Sn halide perovskite solar cells, the mechanistic roles of SnX2 in the performance enhancement have not yet been studied appropriately. Here we perform a comparative study of CsSnI3 films and devices and examine how SnX2 additives affect their stability, and the results are corroborated by first-principles-based theoretical calculations. Unlike the conventional belief that the additives annihilate defects, we find that the additives effectively passivate the surface and stabilize the perovskite phase, promoting the stability of CsSnI3. Our mechanism suggests that SnBr2, which shows ca. 100 h of prolonged stability along with a high power conversion efficiency of 4.3%, is the best additive for enhancing the stability of CsSnI3.
Bibliographical noteFunding Information:
This research was supported by National R&D Program through the National Research Foundation of Korea (NRF) (NRF-2015M1A2A2055836, NRF-2018R1A2B6007888, NRF-2017M3A7B4041698) and New & Renewable Energy Core Technology Program of the Korea Institute of Energy Technology Evaluation and Planning (KETEP) (No. 20183010013820). Supercomputing resources including technical support were supported by the Supercomputing Center/ Korea Institute of Science and Technology Information (KSC-2017-C2-0038).
© 2018 American Chemical Society.
ASJC Scopus subject areas
- Materials Science(all)
- Physical and Theoretical Chemistry