Recent advancements and manipulation strategies of colloidal Cs_(2)B^(I)B^(III)X_(6)lead-free halide double perovskite nanocrystals

Double-metallic lead-free halide perovskites,Cs_(2)B^(I)B^(III)X_(6),sharing three-dimensional crystal structure,have been under the spotlight as the promising alternatives for the toxic and instable lead-based counterparts.Interest in Cs_(2)B^(I)B^(III)X_(6)motivates intense research into their colloidal nanocrystals(NCs).Recently,Cs_(2)B^(I)B^(III)X_(6)NCs have made great progress in the optical performance via alloying or doping,but there are still great challenges for optoelectronic applications.In this review,the latest advances of Cs_(2)B^(I)B^(III)X_(6)NCs in synthesis approaches,bandgap engineering,photoluminescence(PL)optimization,and applications are summarized.The focus is put upon the composition-property relationships of Cs_(2)B^(I)B^(III)X_(6)NCs,which is approached by discussing the influences of composition variation on the electronic states,carrier dynamics,and optical properties.The challenges and the corresponding improving strategies in the development of high-effective and stable Cs_(2)B^(I)B^(III)X_(6)NCs for device applications are also highlighted.It is believed that this review can deepen the understanding on this burgeoning material system and shed light on their future research directions.