Metal halide perovskites (MHPs) have been developed rapidly in light-emitting diodes (LEDs), laser, solar cells, photodetectors and other fields in recent years due to their excellent photoelectronic properties, which attract more researchers’ attention. Perovskite LEDs show great promise in the next generation of lighting and display technologies, and external quantum efficiency (EQE) values of polycrystalline thin-film perovskite LEDs (PeLEDs) exceed 20%, which are undoubtedly identified as a big breakthrough in lighting and display fields. However, toxicity and instabilities of lead-based MHPs remain major obstacles limiting their further commercial applications. The exploration and development of lead-free MHPs (LFMHPs) are regarded as most facile strategies to solve these problems. Compared with lead-based perovskites, LFMHPs exhibit better stabilities and broadband emission. With continuous development of LFMHPs, their photoluminescence quantum yields (PLQYs) are up to 99%, facilitating them as ideal emitters. In this review, structures and features of LFMHPs are analyzed firstly, and preparation methods of LFMHP with various structures and configuration are discussed. Then, mechanisms and strategies for improving emission performance of white LEDs based on LFMHPs are demonstrated. Finally, their challenges in commercial production and perspectives are prospected.
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