High-Resolution Flexible X-ray Imaging in a Two-Dimensional Mn²⁺-Doped Perovskite Scintillator

Flexible scintillator screens characterized by high spatial resolution, low cost, and a simple fabrication process are in significant demand for applications in medical diagnosis and industrial detection. Here, we have demonstrated a new Mn²⁺-doped two-dimensional (2D) Ruddlesden-Popper type perovskite, (4-tert-butylbenzylamine)₂PbBr₄:Mn, serving as a highly efficient scintillator candidate. Doping with Mn²⁺ induces a spin-forbidden internal transition (⁴T_1g → ⁶A_1g) that enhances the energy-transfer efficiency from the strongly bound excitons of the host material to the d electrons of the Mn²⁺ ions, ultimately leading to intense orange-red emission. This process enhances the photoluminescence quantum yield of (4-tert-butylbenzylamine)₂PbBr₄ (1) and decreases its self-absorption. Therefore, at the optimal Mn²⁺-doping concentration, 1:8.4%Mn²⁺ demonstrates a high light yield of 21,532 Ph/MeV and a low detection limit of 198.19 nGy_air s^-1, exceeding the performance of a commercial bismuth germanium oxide (BGO) scintillator. Furthermore, we combined ultrafine powders of 1:8.4%Mn²⁺ with poly(dimethylsiloxane) to fabricate flexible scintillator films. With the optimal film thickness and mass percentage of 1:8.4%Mn²⁺, the scintillator films achieve their maximum spatial resolution of 17.3 lp mm^-1. The above results indicate that the exceptional flexible scintillation imaging performance of 1:8.4%Mn²⁺ effectively addresses the shortcomings of current commercial scintillators, thereby providing a new option for the scintillator family.