Abstract
Mixing halides in metal halide perovskites (MHPs) is an effective approach for adjusting the MHPs bandgap for applications in tandem solar cells. However, mixed-halide (MH-) MHPs undergo light-induced phase segregation (LIPS) under continuous illumination. Therefore, understanding the mechanism of LIPS is necessary for developing stable MH-MHPs. In this work, we investigated LIPS in layered (L) MHPs and discovered a critical role of spacer cations in LIPS. Through probing chemical changes of LIPS, we unveil light-induced iodide repulsion and the formation of Br-rich-phase in illuminated regions during LIPS. This discovery also gives insight into the LIPS process in three-dimensional (3D) MHPs. By further investigating LIPS in 3D MHPs, we reveal that LIPS induces not only the formation of Br-rich and I-rich domains but also an overall change of halide distribution along the film thickness direction. Moreover, LIPS is more significant in bulk due to a larger population of photogenerated charge carriers. Overall, this study reveals the chemical mechanism of LIPS in MHPs and its potential effect on device performance, offering insight into understanding the LIPS mechanism and improving the stability of MHPs.
| Original language | English |
|---|---|
| Article number | 100197 |
| Journal | Materials Today Nano |
| Volume | 18 |
| DOIs | |
| State | Published - Jun 2022 |
Funding
The work (materials synthesis and ToF-SIMS characterization) was supported by the Oak Ridge National Laboratory's Center for Nanophase Materials Sciences, a U.S. Department of Energy, Office of Science User Facility and through the DOE Office of Science Research Program for Microelectronics Codesign (sponsored by ASCR, BES, HEP, NP, and FES) through the Abisko Project, PM Robinson Pino (ASCR). This work uses instrumentation within ORNL's Materials Characterization Core provided by UT-Battelle, LLC under Contract No. DE-AC05-00OR22725 with the U.S. Department of Energy. M.A. acknowledges support from National Science Foundation (NSF), Award Number # 2043205. The work (materials synthesis and ToF-SIMS characterization) was supported by the Oak Ridge National Laboratory’s Center for Nanophase Materials Sciences, a U.S. Department of Energy, Office of Science User Facility and through the DOE Office of Science Research Program for Microelectronics Codesign (sponsored by ASCR, BES, HEP, NP, and FES) through the Abisko Project, PM Robinson Pino (ASCR). This work uses instrumentation within ORNL’s Materials Characterization Core provided by UT-Battelle, LLC under Contract No. DE-AC05-00OR22725 with the U.S. Department of Energy. M.A. acknowledges support from National Science Foundation (NSF) , Award Number # 2043205 . Notice: This manuscript has been authored by UT-Battelle, LLC, under Contract No. DE-AC0500OR22725 with the U.S. Department of Energy. The publisher, by accepting the article for publication, acknowledges that the United States Government retains a non-exclusive, paid-up, irrevocable, worldwide license to publish or reproduce the published form of this manuscript, or allow others to do so, for the United States Government purposes. The Department of Energy will provide public access to these results of federally sponsored research in accordance with the DOE Public Access Plan ( http://energy.gov/downloads/doe-public-access-plan ).
Keywords
- Chemical distribution
- Metal halide perovskites
- Phase segregation
- Spacer cation effect
