Cascade perovskite single crystal for gamma-ray spectroscopy.

The halide lead perovskite single crystals (HLPSCs) have great potential in gamma-ray detection with high attenuation coefficient, strong defects tolerance, and large mobility-lifetime product. However, mobile halide ions would migrate under high external bias, which would both weaken the gamma-ray response and cause additional noise. Here, we report the gamma-ray PIN photodiodes made of cascade HLPSCs including both ion-formed and electron-hole-formed electrical junctions that could suppress the ions migration and improve the charges collection. Our photodiodes based on cascade HLPSCs (MAPbBr/MAPbBrCl/MAPbCl) show a wide halide-ion-formed depletion layer of ∼52 μm. The built-in potential along the wide ionic-formed junction ensures a high mobility-lifetime product of 1.1 × 10 cmV. As a result, our gamma-ray PIN photodiodes exhibit compelling response to Am, Cs, and Co; the energy resolution can reach 9.4%@59.5keV and 5.9%@662keV, respectively. This work provides a new path toward constructing high-performance gamma-ray detectors based on HLPSCs.