Recent Advances and Optoelectronic Applications of Lead-Free Halide Double Perovskites.

Organic-inorganic metal halide perovskites (most notably CH 3 NH 3 PbI 3 ) have demonstrated remarkable physical attributes for photovoltaic and diverse optoelectronic applications, whereas the concerns on toxicity of the lead (Pb) content in chemical composition still motivate further exploration of new nontoxic candidates. Lead-free halide double perovskites (HDPs), designed by the rational chemical substitution of Pb 2+ with other nontoxic candidate elements, are recently booming as fascinating alternative to Pb-based counterparts. Herein, we overview recent advances in crystal structures, physical properties and versatile optoelectronic applications of lead-free HDPs, such as solar cells, photodetectors, X-ray detectors and light-emitting diodes. Perspectives to improve physical and photoelectric properties of the existing HDP materials have also been discussed that will favor future development of new lead-free HDP candidates.