We show that the recombination rate from excitons in Lead Halide Perovskite (LHP) polycrystalline thin films is suppressed, rather than enhanced, when they are placed on hyperbolic metamaterials and a plasmonic substrate by 30% and 50%, respectively. We reveal that these LHP films enjoy a dominant in-plane transition dipole, which is responsible for the decrease in the recombination rate. In triple cation LHPs we observe a 10-fold decrease in the recombination rate, comparable to recombination rate suppression obtained by Photonic Crystal cavities. By controlling the recombination rate of LHPs, we demonstrate a 250% increase in photoresponsivity of LHP-based photodetectors.
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