Proceedings of International Conference on Hybrid and Organic Photovoltaics (HOPV19)
DOI: https://doi.org/10.29363/nanoge.hopv.2020.095
Publication date: 6th February 2020
Methylammonium lead iodide (MAPI), which is the halide perovskite that is currently in the focus of photovoltaic research because of its high conversion efficiencies. In this contribution we discuss equilibrium space charge effects in MAPI and concentrate on the MAPI/TiO2 and MAPI/Al2O3 contacts. Irrespective of polarization phenomena building up under operation, already the equilibrium situation is dominated by space charge effects (built-in space charge). While such equilibrium space charge effects are only considered in terms of electronic charge carrier redistribution, we will apply a generalized picture that discusses both ionic and electronic redistribution. We fine that ionic carriers are not only relevant, but they even dictated the space charge potential which the electrons have to follow (fellow-traveler effect). Our analysis is based on the measurement of electronic and ionic conductivities in MAPI/TiO2 and MAPI/Al2O3 composites, a technique that has been successfully applied in solid states ionics [1-3]. Those findings give strong indications of ionically-driven equilibrium space potentials forming at the MAPI/TiO2 and MAPI/Al2O3 interfaces. This study provides a completely new perspective for interfacial research in lead halide perovskites.
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[3] H. Yamada, A. J. Bhattacharyya, J. Maier, Adv. Func. Mater. 2006, 16, 525-530.