Nonlinear Response and Origin of Slow Component of Two-Dimensional Perovskite Scintillator

Two-dimensional organic-inorganic perovskites have displayed significant potential as scintillators in radiation detection, owing to their outstanding scintillation properties, including fast decay time and high light yield. Understanding the nonlinear response and the origin of the slow component is crucial for their application in pulsed radiation environments, necessitating an in-depth investigation. In this study, we successfully synthesized lithium-doped phenylethylammonium lead bromide (LPEA) perovskite single crystals and conducted a comprehensive analysis of their scintillation performance. LPEA exhibited intense blue emission peaks at 411 and 434 nm when excited by a 320 nm laser and X-rays, respectively, with a relatively narrow emission spectrum (full width at half-maximum of 11 and 27 nm). Under Cs-137 excitation, LPEA displayed two decay components: an 8 ns component accounting for 90% of the decay and a 22 ns component accounting for the remaining 10%. We investigated the nonlinear response under pulsed radiation excitation with varying energies and dose rates. Our results demonstrated that LPEA exhibited a nonlinear response under high dose-rate excitation, with the nonlinearity becoming more pronounced as the energy and dose rate of the radiation source increased. To provide a detailed explanation of the nonlinear response, we developed a novel photophysical model consisting of bright and dark states. According to our findings, the increased contribution of the dark state accounted for the nonlinear response of LPEA. Additionally, we confirmed that the dark state was responsible for the slow component observed in the decay behavior.