Metal halide perovskites exhibit outstanding optical and electronic properties, but are very sensitive to humidity and light-soaking. In this work, the photophysics of perovskites that have been exposed to such conditions are studied and, in this context, the impact of excess lead iodide (PbI2) is revealed. For exposed samples, the formation of subbandgap states and increased trap-assisted recombination is observed, using highly sensitive absorption and time-resolved photoluminescence (TRPL) measurements, respectively. It appears that such exposure primarily affects the perovskite surface. Consequently, on n–i–p device level, the spiro-OMeTAD/perovskite interface is more rapidly affected than its buried electron-collecting interface. Moreover, both stoichiometric and nonstoichiometric MAPbI3-based solar cells show reduced device performance mainly due to voltage losses. Overall, this study brings forward key points to consider in engineering perovskite solar cells with improved performance and material stability.
Bibliographical noteFunding Information:
This publication is based upon work supported by the King Abdullah University of Science and Technology (KAUST) Office of Sponsored Research (OSR) under Award No.: OSR‐2018‐CARF/CCF‐3079. E.U. and F.L. thank K. Vandewal and M. Baier for contributing to the setup for photothermal deflection spectroscopy (PDS). M.L. and A.V. acknowledge the support of Czech Science Foundation Project No. 17‐26041Y, Operational Programme Research, Development, and Education financed by the European Structural and Investment Funds and the Czech Ministry of Education, Youth and Sports (Project No. CZ.02.1.01/0.0/0.0/16_019/0000760 – SOLID21) and CzechNanoLab Research Infrastructure supported by MEYS CR (LM2018110).
© 2020 Wiley-VCH GmbH
- metal halide perovskites
- perovskite photophysics
- perovskite solar cells
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Atomic and Molecular Physics, and Optics
- Energy Engineering and Power Technology
- Electrical and Electronic Engineering