UC Riverside

Charge transfer (CT) is an essential part of life. Ubiquitous in nature, CT is the principal foundation for biological processes, solar-energy conversion and electronics. Understanding CT processes at the molecular and nanoscale levels and interface between them is essential for energy science, biomedical advances, and organic electronics. As important as interfacing, or “wiring,” molecular moieties with conducting solid substrates is for materials and device development, it still remains a formidable challenge. Over the last decade lead halide perovskite compositions have attracted tremendous interests due to their uniquely promising electronic and optical properties. The dynamic nature of ligand binding to such materials makes the wiring of CT molecular moieties to them especially challenging.

Here we show how effective interfacing between semiconducting all inorganic CsPbBr3 perovskite nanocrystals and electron donating molecules facilitates charge transfer. We illustrate the important dual benefits that a binding motif offers: (1) electronic coupling essential for efficient interfacial CT and (2) surface-trap passivation eliminating non-radiative pathways of exciton deactivation. Aliphatic amines show the strongest known propensity for perovskite surfaces. We show that an increase in the amounts of such Lewis bases etches the perovskite material, changing the shape and size of the nanocrystals and degrading them. Our results demonstrate that concentration control allows for optimal loading of amine moieties on perovskite nanomaterials without compromising their morphology, permitting efficient interfacial CT even in non-polar media. These findings reinforce and open doors for a wide range of photonics and electronics applications including solar-energy conversion, photocatalysis and molecular electronics.