Dexter-type charge carrier transfer from colloidal metal halide perovskite nanocrystals (PNCs) showed potential in photocatalysis and photon upconversion applications. In this work, we demonstrated that through tunning the adsorption mode of molecular charge carrier acceptors, we were able to manipulate the dynamics of Dexter processes on the surface of CsPbBr<sub>3</sub> nanocrystals. On the pre-treated PNC surface, we realized the controlled adsorption of molecular acceptors, such as quinoline and naphthalene derivatives, by carefully selecting the binding strengths of the anchoring motifs of these molecular acceptors relative to the intrinsic surface ligands after modification. NMR spectroscopy and steady-state photoluminescence quenching experiments identified that the binding modes of molecular acceptors varied from dynamic exchange on and off the PNC surface to tight static anchoring. Time-resolved photoluminescence and transient absorption spectroscopy provided kinetic information for photo-induced hole transfer to the quinoline acceptor and triplet energy transfer to the naphthalene acceptor under different binding conditions. A quantitative evaluation of the binding of acceptors and the charge carrier migration rates suggests the existence of special sites on the PNC surface that matches particular binding motifs, which served as hot spots for efficient Dexter-type processes. The work provided design principles of surface ligand chemistry for fabricating photosensitizers that can utilize the superb optical property of the PNC.

Surface engineering strategy for manipulating Dexter charge carrier transfer on metal halide perovskite nanocrystals

ACS Spring 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.