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

Abstract 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 × 10 4 A W −1 ) and an external quantum efficiency (EQE) of 3 × 10 6 %. These numbers are among the highest for perovskite‐NC‐based photodetectors.