Alcohol-Soluble Quantum Dots: Enhanced Solution Processability and Charge Injection for Electroluminescence Devices

General and versatile ligand exchange routes are developed for converting nonpolar solvent soluble quantum dots to alcohol-soluble. Through ligand exchange, long-chain methyl-terminated oleylamine on quantum dots' surface can be substituted by short-chain hydroxyl-terminated 6-mercaptohexanol, enabling their dispersibility in polar organic solvents including methanol, ethanol, isopropanol, and dimethylformamide. The resulted alcohol-soluble quantum dots maintained their optical properties and perfectly fit the requirements for solution-processed electroluminescence devices. Light emitting diode based on the alcohol-soluble quantum dots eclipsed their counterparts made from nonpolar solvent soluble quantum dots. The improvement of device performance is ascribed to decreased energy barriers and increased charge injection rate between charge transport layer and the emitting layer. The hydroxyl-terminated quantum dots provide a new materials platform for the design of highly efficient quantum dot light emitting diodes, and also enable an alternative route to achieve RGB display devices.