Enhancing aqueous stability and radiative-charge-transfer efficiency of CsPbBr3 perovskite nanocrystals via conductive silica gel coating

Abstract

The poor aqueous stability of perovskite nanocrystals (NCs) limits their electrochemical applications. Herein, we reported a waterproof and conductive silica gel shell encapsulating CsPbBr3 NCs, enhancing its aqueous stability and radiative-charge-transfer efficiency. Upon introducing small volume of CsBr aqueous solution in hexane containing tetramethoxysilane (TMOS) and Cs4PbBr6 NCs, the conversion reaction of Cs4PbBr6 → CsPbBr3+3CsBr was triggered to form Cs4PbBr6@CsPbBr3@silica gel (CsBr) hybrid. The silica gel shell can block the contact between CsPbBr3 NCs and bulk aqueous phase. The CsBr enclosed in the silica gel can reduce the conversion rate and increase dramatically the electrical conductivity of the silica gel. The electrochemiluminescence (ECL) of CsPbBr3 NCs in aqueous phase was enhanced greatly. The strong ECL of CsPbBr3 NCs in the hybrid was still observed after stored in CsBr solution for 30 day. The as-obtained perovskite hybrid displays improved electrochemical charge-injecting performance and radiative-charge-transfer in ECL. Annihilation ECL demonstrates that all the electrons injected onto the perovskite hybrid can recombine with the holes injected onto it for light-emitting. Both annihilation and co-reactant ECL, as well as photoluminescence reveal that encapsulating CsPbBr3 NCs into a conductive and waterproof silica gel shell is favorable to enhance aqueous performance of perovskite NCs with negligible effects on their excited states. The ECL of the core-shell perovskite hybrid was applied to detect dopamine in the concentration range of 0.01–10 μM, with the limit of detection of 3 nM.