Lead-free perovskites and derivatives enable direct and scintillation-type X-ray detection

Lead halide perovskites with excellent optoelectronic properties have attracted extensive attention and made amazing progress for X-ray detectors and imaging. However, lead is highly toxic to humans, animals and ecosystems, posing a great safety concern to its commercial application. It has become an urgent need to develop stable and environment-friendly lead-free alternatives. In this review, we summarize recent progress in lead-free halide perovskites (LFHPs) and derivatives toward X-ray detectors and imaging. First, we introduce the working principle of X-ray detectors and the key figure of merit in direct and indirect detection processes. In addition, we summarize state-of-the-art lead-free halide perovskites preparation methods. Furthermore, we comprehensively discuss the structural dimensions, optoelectronic properties of lead-free halide perovskites and their recent advances in X-ray detection and imaging. Meanwhile, the stabilities of LFHPs-based X-ray detectors are discussed. Finally, we outline several main issues of state-of-the-art LFHPs-based X-ray detectors and provide prospects to overcome these limitations.