Recent Progress of Eco-friendly Lead-free Halide Perovskite Light-Emitting Diodes

Metal halide perovskites (MHPs) are promising candidate materials for next-generation optoelectronic device applications such as light-emitting diodes (LEDs), solar cells, and photodetectors. However, the toxicity and poor stability issues of lead-based MHPs (LHPs) are still challenging to fulfill a restriction of hazardous substances directive (RoHS) and industrial standards for the commercialization of LHP devices. Therefore, eco-friendly and lead-free halide perovskites (EHPs), which are superior to LHPs, should be developed. In this review, we will review the promising strategies to substitute a lead cation with non-toxic metal cations such as tin (Sn), bismuth (Bi), antimony (Sb), and copper (Cu), and discuss the synthetic methods, crystal structures, luminescent properties, and their LED applications.