Promoting Band Splitting through Symmetry Breaking in Inorganic Halide Perovskite Single Crystals for High-Sensitivity X-ray Detection

We propose a band-splitting strategy driven by breaking the crystal structure symmetry by partially replacing Br– ions with larger I– ions in the CsPbBr3 single crystal (SC). Experimental results show that the photoelectric properties of the band-split SCs are significantly improved due to the asymmetric crystal structure and distinct band splitting, which inhibits ion migration and promotes transport of carriers, respectively. It is found that the band-split SCs exhibit higher resistivity, larger mobility-lifetime product, and lower ion migration than the pristine SCs. Therefore, detectors fabricated on the band-split SCs achieved a record X-ray detection sensitivity of 2.8 × 105 μC Gy–1 cm–2 for the inorganic perovskite, low detection limit of 18 nGy s–1, and high resolution of 12.7 lp mm–1 in imaging. In addition, the X-ray detection stability of the band-split SC detectors has also been significantly improved, and the detectors still show high sensitivity (1.2 × 104 μC Gy–1 cm–2) at temperatures of up to 100 °C.