Tailoring Charge Donor-Acceptor Interaction in CsPbBr3 Perovskite Nanocrystals through Ligand Exchange

TL;DR

This study demonstrates how ligand exchange in CsPbBr3 nanocrystals with short-chain butylamines modulates their interaction with TiO2, affecting optoelectronic properties and donor-acceptor interactions.

Contribution

It introduces a ligand exchange method to tailor charge donor-acceptor interactions in perovskite nanocrystals, impacting their optoelectronic behavior.

Findings

Butylamine ligands reduce photoluminescence intensity with TiO2 in solution.

Both ligand types show decreased PL lifetime in films with TiO2, indicating enhanced interactions.

TiO2 nanotubes increase nonradiative recombination more in butylamine-capped nanocrystals.

Abstract

The surface ligands in colloidal metal halide perovskites influence not only their intrinsic optoelectronic properties but also their interaction with other materials and molecules. We explore donor-acceptor interactions of CsPbBr3 perovskite nanocrystals with TiO2 nanoparticles and nanotubes by replacing long-chain oleylamine ligands with short-chain butylamines. Through post-synthesis ligand exchange, we functionalize the nanocrystals with butylamine ligands while maintaining their intrinsic properties. In solution, butylamine-capped nanocrystals exhibit reduced photoluminescence intensity with increasing TiO2 concentration but without any change in photoluminescence lifetime. Intriguingly, the Stern-Volmer plot depicts different slopes at low and high TiO2 concentrations, suggesting mixed static and sphere-of-action quenching interactions. Oleylamine-capped nanocrystals in solution, on the other hand, show no interaction with TiO2, as indicated by consistent photoluminescence intensities and lifetimes before and after TiO2 addition. In films, both types exhibit decreased photoluminescence lifetime with TiO2, indicating enhanced donor-acceptor interactions, which are discussed in terms of trap state modification and electron transfer. TiO2 nanotubes enhance nonradiative recombination more in butylamine-capped CsPbBr3 perovskite nanocrystals, emphasizing the role of ligand chain length.