Photo-induced enhancement of lattice fluctuations in metal-halide perovskites

• DOI: 10.1038/s41467-022-28532-0
• Publication Date: 2022-02-23T11:03:09Z
• Authors: Mingcong Wang; Yajun Gao; Kai Wang; Jiang Liu; Stefaan De Wolf; Frédéric Laquai
• Keywords: Photoexcitation; Lattice (music); Charge carrier

The optoelectronic properties of metal-halide perovskites (MHPs) are affected by lattice fluctuations. Using ultrafast pump-probe spectroscopy, we demonstrate that in state-of-the-art mixed-cation MHPs photo-induced bandgap narrowing occurs with a linear to super-linear dependence on the excited carrier density ranging from 1017 cm-3 above 1018 cm-3. Time-domain terahertz spectroscopy reveals localization increases density. Both observations, anomalous and increased can be rationalized magnitude fluctuations depends intrinsic instability MHP lattice. Our findings provide insight into processes following photoexcitation thus help develop concise picture photophysics this important class emerging semiconductors.