The working principle of hybrid perovskite gamma-ray photon counter

Gamma-ray spectroscopy that quantifies the gamma-ray energies is a critical technology widely needed in astrophysics, nuclear material detection and medical treatment. The key is to precisely count gamma-ray photons using sensitive detectors. In this paper, we investigate the operational principles of chlorine-doped methylammonium lead tribromide (MAPbBr_3−xCl_x) perovskite single crystal detectors that can efficiently count gamma-ray photon events with electrical pulses. Specifically, we find the main dark current originates from the thermally activated electron injection from the impurities, and using high work function contacts can block out the dark noise thus allows for efficient pulse collection at higher electrical fields ∼500 V/cm. As a result, we observe strong electrical pulses when exposing the detector under radioactive sources emitting gamma-ray photons at various energies. Our results also reveal the fundamental issues that prevent the reliable observation of photo-electric peak. This work suggest pathway towards energy resolved gamma-ray spectroscopy using perovskite crystal detectors.