Ultrafast (600 ps) Vacuum‐UV Reflective Scintillation Enabled by Surface Exciton Recombination in Layered Perovskite PEA ₂ PbBr ₄

Abstract

Abstract Vacuum ultraviolet (VUV) photodetection is pivotal for space exploration and radiation monitoring, yet its dynamic imaging capability is significantly hindered by the slow response of conventional scintillators. However, existing scintillators exhibit microsecond‐to‐nanosecond decay time, failing to meet sub‐nanosecond ultrafast imaging demands. Here, we uncovered a surface exciton recombination mechanism in layered perovskite PEA 2 PbBr 4 , where lattice contraction induced exciton localization, achieving ultrafast decay time of 600 ps—over 100‐fold faster than commercial scintillation. A reflective optical configuration was designed to suppress self‐absorption, improving the light utilization efficiency. This work established a material paradigm for ultrafast dynamic imaging and opens avenues for advancing space science and high‐energy physics detection.