Ambipolar Charge Transport in Perovskite CsPbBr <sub>3</sub> γ‐Ray Detectors with Superior Uniformity and Spectral Resolution by Zone Refining Processing
Bao Xiao, Yuquan Wang, Ning Ding, Haoming Qin, Nan‐Nan Shen, Xuchang He, Qihao Sun, Yihui He
Abstract
Abstract Perovskite semiconductor cesium lead bromide (CsPbBr 3 ) has demonstrated great promise as a new‐generation gamma‐ray detector. However, substantial challenges still present in reproducibly achieving optimal spectroscopic performance. The specific strategy for producing spectroscopic‐grade CsPbBr 3 crystals with high reproducibility and uniformity are still not clarified. Herein, efficient zone refining processing is developed for CsPbBr 3 crystals that facilitates impurity segregation to achieve an ultrahigh purity level of ≈1.42 ppm, therefore lowers trap density and balances charge transport. In a typical 30 mm diameter zone‐refined CsPbBr 3 ingot, all wafers exhibited remarkable energy resolutions of 6–12% and 3–8% for 241 Am and 57 Co γ‐rays under comparable electric fields. The crystals also exhibited an ambipolar charge transport characteristic, resemble to elemental semiconductors, with equivalent hole and electron mobility‐lifetime products averaging 5.42 × 10 −3 and 2.27 × 10 −3 cm 2 ∙V −1 , respectively. Consequently, over 95% of wafers achieved energy resolutions below 5% whereas 70% exceeded 3% for 137 Cs γ‐rays, demonstrating exceptional reproducibility and uniformity. Notably, a champion energy resolution of 1.3% with an outstanding photopeak‐to‐Compton (P/C) ratio of ≈5.3 is attained in an ambipolar planar detector. It is anticipated that this work shall expedite scalable manufacturing and practical applications of CsPbBr 3 detectors.