Gigantic suppression of recombination rate in 3D lead-halide perovskites for enhanced photodetector performance

Prolonging the carrier lifetime in lead-halide perovskite (LHP) can enable novel schemes for highly efficient energy-harvesting and photodetection applications. However, suppressing the recombination processes in LHP without chemical treatments remains an open challenge. Here we show that the recombination rate of three-dimensional LHP polycrystalline thin films can decrease significantly when placed on hyperbolic metamaterials. Through momentum-resolved imaging, we reveal that these LHP films possess a dominant in-plane transition dipole, which in turn is responsible for the decrease in the recombination rate. We observe a decrease in the recombination rate of a MAPbI₃ LHP thin film by ~50% and 30% when placed on a plasmonic mirror and a hyperbolic metamaterial, respectively. Furthermore, we discover a tenfold decrease in the recombination rate of (Cs_0.06FA_0.79MA_0.15)Pb(I_0.85Br_0.15)₃, and the origin of this giant reduction in the recombination process is discussed based on exciton-trapping dynamics. By controlling the recombination rate of LHPs, we demonstrate a 250% increase in photoresponsivity of LHP-based photodetectors. The resulting physical insights will provide novel means to enhance the efficiency of LHP-based optoelectronic and photonic devices.