Colloidal lead-free Cs_(2)AgBiBr_(6)double perovskite nanocrystals:Synthesis,uniform thin-film fabrication,and application in solution-processed solar cells

摘要

Recently developed lead-free double perovskite nanocrystals(NCs)have been proposed for the possible application in solutionprocessed optoelectronic devices.However,the optoelectronic applications of double perovskite NCs have been hampered due to the structural and chemical instability in the presence of polar molecules.Here,we report a facile strategy for the synthesis and purification of Cs_(2)AgBiBr_(6)double perovskite NCs that remained stable even after washing with polar solvent.This is realized with our efficient colloidal route to synthesize Cs_(2)AgBiBr_(6)NCs that involve stable and strongly coordinated precursor such as silvertrioctyl phosphine complex together with bismuth neodecanoate,which leads to a significantly improved chemical and colloidal stability.Using layer-by-layer solid-state ligand exchange technique,a compact and crack-free thin film of Cs_(2)AgBiBr_(6)NCs were fabricated.Finally,perovskite solar cells consisting of Cs_(2)AgBiBr_(6)as an absorber layer were fabricated and tested.