Bifunctional Ligand Strategy for Suppressing Perovskite Quantum Dot Defects and Enhancing Photodetector Performance

Although lead halide perovskite nanocrystals are promising for optoelectronic device applications, the instability of quantum dots and the low carrier transport efficiency of conventional long-chain ligands seriously hinder their further applications. To overcome these limitations, the terminal bifunctional ligands passivation strategy is employed in this paper to explore the effects of varying chain lengths, flexibilities, and conjugation degrees on carrier transport. The findings demonstrate that bifunctional ligands can form connections between quantum dots. However, excessive chain length or low flexibility will result in an increase in defects and a decrease in the carrier transport efficiency between quantum dots. Methylammonium succinate ligands were selected to passivate the defects on the surface of the quantum dots while increasing the carrier-transfer efficiency between the quantum dots, allowing them to provide photodetector responsivities that are 96 times higher than those of conventional oleic acid-passivated quantum dots.