Substrate-modulated transition dipole moment orientation in perovskite nanocube thin film

Inorganic lead halide perovskite nanocrystals (CsPbX₃ (X=halide)) exhibit highly anisotropic, uniquely surface-sensitive emission [1]. Here, we explored how the unique surface sensitivity of perovskite nanocrystals can be exploited to modify the mode of light emission, as emission angle determines the efficiency of an electronic device. We show that the angular photoluminescence pattern of LHP nanocrystal thin films can be modified by changing its local optical/electronic environment through substrate modifications. LHP nanocubes were synthesized and deposited onto various substrates, including treated glass, LHP nanoplates, and a soft polymer (PMMA). We used Back Focal Plane fluorescence microscopy combined with an LDOS model to determine the mode of light emission, showing isotropic light emission for the polymer substrate and preferential emission into the substrate for all other samples. Thus, by depositing very thin layers of polymer or nanocrystals, we can strongly tune the light emission direction for this material system.



[1] M. J. Jurow, et al. Nano Lett. 19 (2019): 2489.