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Correlated nanoimaging of structure and dynamics of cation-polaron coupling in hybrid perovskites

Wilcken, Roland1; Esses, Branden L.1; Nithyananda Kumar, Rachith S.1; Hurley, Lauren A.1; Shaheen, Sean E.1; Raschke, Markus B.1

Research facility: University of Colorado Boulder
Published Feb 06, 2025 on Dryad. https://doi.org/10.5061/dryad.zs7h44jkd

Data files

Feb 06, 2025 version files 891.50 MB
Feb 06, 2025 version files 891.50 MB

Abstract

Hybrid organic-inorganic perovskites exhibit high photovoltaic performance and other novel photonic functions. While polaron formation is believed to facilitate efficient carrier transport, the elementary processes of the underlying electron-lattice coupling are yet poorly understood because of the multi-scale chemical and structural heterogeneities. Here, we resolve in the combined ground and excited state spatio-spectral ultrafast nanoimaging how structural characteristics are related to both molecular cation and polaron dynamics. We observe nano-scale spatial variations of the formamidinium (FA) cation transient vibrational blue shifts used as a local probe of the non-local polaron-cation coupling. From the correlation with nano-movies of the polaron dynamics, we then infer how a softer more polarizable lattice supports stabile polarons and longer-lived residual carriers. This, together with a relative intra-grain homogeneity in contrast to high inter-grain heterogeneity thus suggests pathways for improved synthesis and device engineering, and that perovskite photonics performance is still far from any fundamental limits.