Lead (Pb) halide perovskite nanocrystals, with the general formula APbX3, where A=CH3NH3+, CH(NH2)2+, or Cs+ and X=Cl−, Br−, or I−, have emerged as a class of materials with promising properties due to their remarkable optical properties and solar cell performance. However, important issues still need to be addressed to enable practical applications of these materials, such as instability, mass production, and Pb toxicity. Recent studies have carried out the replacement of Pb by various less‐toxic cations as Sn, Ge, Sb, and Bi. This variety of chemical compositions provide Pb‐free perovskite and metal halide nanostructures with a wide spectral range, in addition to being considered less toxic, therefore having greater practical applicability. Highlighting the necessity to address and solve the toxicity problems related to Pb‐containing perovskite, this review considers the prospects of the Pb‐free perovskite, involving synthesis methods, and properties of them, including advantages, disadvantages, and applications.

Despite all the recent progress on understanding the optoelectronic and structural properties of the CsPbX3 perovskite nanocrystals (PNCs), the impact of the ligands on their photostability, under continuous UV light...