Efficient Luminescent Halide Quadruple-Perovskite Nanocrystals via Trap-Engineering for Highly Sensitive Photodetectors.

The colloidal synthesis of a new type of lead-free halide quadruple-perovskite nanocrystals (NCs) is reported. The photoluminescence quantum yield and charge-carrier lifetime of quadruple-perovskite NCs can be enhanced by 96 and 77-fold, respectively, via metal alloying. Study of charge-carrier dynamics provide solid demonstrate that the PL enhancement is due to the elimination of ultrafast (1.4 ps) charge-carrier trapping processes in the alloyed NCs. Thanks to the high crystallinity, low trap-state density, and long carrier lifetime (193.4 μs), the alloyed quadruple-perovskite NCs can serve as the active material for high-performance photodetectors, which exhibit high responsivity (up to 0.98 × 104 A W-1 ) and an external quantum efficiency (EQE) of 3 × 106 %. These numbers are among the highest for perovskite-NC-based photodetectors.