Unraveling the Effect of Surface Ligands on the Auger Process in anInorganic Perovskite Quantum-Dot System

This work systematically scrutinizes the role of surface-ligand modification inaffecting the Auger process in a porotype perovskite system of CsPbBr3-octanoic acid (OcA)and CsPbBr3-oleic acid (OA) quantum dots (QDs), by means of steady-state/time-resolved/temperature-dependent photoluminescence spectroscopy and ultrafast transient absorptionspectroscopy. The difference in the ligand chain length (i.e., C8and C18alkyl chains for OcAand OA, respectively) is found to significantly affect Auger recombination and hot-carriercooling processes. More importantly, we provide fresh insight into the involved carrierdynamics; i.e., the modification of CsPbBr3QDs with short-chain (long-chain) ligand leads tothe formation of trapped (free) carriers, which causes a pronounced difference in the ability tosuppress the detrimental Auger process. In addition, a careful analysis of spectral evolutionreveals that the Auger suppression is related to the carrier population of a certain transitionstate. The valuable mechanistic information gleaned from the exciton/carrier dynamicsperspective would assist in surface engineering through a facile ligand-modification strategytoward rational design and optimization of QD-based photoelectrochemical applications.

Automated summary

This work systematically investigates the role of surface-ligand modification on the Auger process in CsPbBr3 quantum dots. The results show that the length of the ligand chain greatly affects Auger recombination and hot-carrier cooling processes. Short-chain (long-chain) ligand modification leads to the formation of trapped (free) carriers, which significantly suppresses the detrimental Auger process.