How photogenerated I2 induces I-rich phase formation in lead mixed halide perovskites

0580310 - ÚMCH 2025 RIV US eng J - Journal Article
Zhou, Y. - van Laar, S. C. W. - Meggiolaro, D. - Gregori, L. - Martani, S. - Heng, J.-Y. - Datta, K. - Jiménez-López, J. - Wang, F. - Wong, E L. - Poli, I. - Treglia, A. - Cortecchia, D. - Prato, M. - Kobera, Libor - Gao, F. - Zhao, N. - Janssen, R. A. J. - De Angelis, F. - Petrozza, A.
How photogenerated I2 induces I-rich phase formation in lead mixed halide perovskites.
Advanced Materials. Roč. 36, č. 1 (2024), č. článku 2305567. ISSN 0935-9648. E-ISSN 1521-4095
Institutional support: RVO:61389013
Keywords : defects * metal halide semiconductors * optoelectronics
OECD category: Polymer science
Impact factor: 29.4, year: 2022
Method of publishing: Open access
https://onlinelibrary.wiley.com/doi/10.1002/adma.202305567

Bandgap tunability of lead mixed halide perovskites (LMHPs) is a crucial characteristic for versatile optoelectronic applications. Nevertheless, LMHPs show the formation of iodide-rich (I-rich) phase under illumination, which destabilizes the semiconductor bandgap and impedes their exploitation. Here, it is shown that how I2, photogenerated upon charge carrier trapping at iodine interstitials in LMHPs, can promote the formation of I-rich phase. I2 can react with bromide (Br−) in the perovskite to form a trihalide ion I2Br− (Iδ−-Iδ+-Brδ−), whose negatively charged iodide (Iδ−) can further exchange with another lattice Br− to form the I-rich phase. Importantly, it is observed that the effectiveness of the process is dependent on the overall stability of the crystalline perovskite structure. Therefore, the bandgap instability in LMHPs is governed by two factors, i.e., the density of native defects leading to I2 production and the Br− binding strength within the crystalline unit. Eventually, this study provides rules for the design of chemical composition in LMHPs to reach their full potential for optoelectronic devices.

Permanent Link: https://hdl.handle.net/11104/0350311