Proceedings of nanoGe Spring Meeting 2022 (NSM22)
DOI: https://doi.org/10.29363/nanoge.nsm.2022.255
Publication date: 7th February 2022
Are all important non-radiative recombination centres in perovskites metastable?
Ivan G. Scheblykin
Chemical Physics and Nano Lund, Lund University, Sweden
Despite of very substantial efforts, it is still difficult to quantitatively account for charge dynamics in metal-halide perovskites over a broad range of excitation condition by the standard theoretical approaches of semiconductor physics.1
One aspect which has never been taken into account in any modelling of this kind is defect metastability. A defect state is metastable if, for example, it undergoes transition from its active state, in this state it induces strong non-radiative (NR) recombination, to its passive state where it does not influence charge dynamics at all.2 Obviously, defect metastability must influence charge carrier dynamics substantially, especially if switching of the defects is light or/and charge carrier concentration dependent. Evidence for the defect metastability is overwhelming:
1. Photoluminescence (PL) blinking of individual microcrystals and even grains of polycrystalline films.3
2. Reversible PL enhancement and PL bleaching4,5
3. Self-healing property of metal-halide perovskites in general terms6
I will discuss how we can see the metastable NR centers in action by observation of PL blinking. I will argue, that most probably all important defect states causing NR recombination, which scientists from all fields from fundamental to applied care about, are, in fact, metastable and see then in PL blinking experiments. So far, I do not see any experimental observations which would disprove to this hypothesis.
Despite that PL blinking in perovskites is known from 2015,7 so far there had been no real connection drawn from the results obtained on individual crystals and properties of films and devices. If all important defects are metastable, understanding this metastability becomes very crucial with PL micro spectroscopy as an ideal tool.
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