Gram-Scale Synthesis of Core–Gradient Shell CdSe/Cd_1–xZn_xSe_1–yS_y/ZnS Quantum Dots with R/G/B Emission Using Eco-Friendly Hydrolyzed Cooking Oils: Implications for Display Applications

We present a method for gram-scale synthesis of colloidal quantum dots (CQDs) with a quantum yield of up to 80% at room temperature and a narrow full width at half-maximum (FWHM) (<35 nm) in a wide range of emission wavelengths (480–619 nm) using a green solvent, cooking oil, either fresh or recycled. Hydrolyzing edible cooking oils such as soybean oil or waste cooking oil (i.e., a low-cost ($1.69/500 mL) and eco-friendly solvent), all in one step can easily generate various fatty acids, serving as green solvents and coordinating surfactants. Adjusting the conditions of hydrolysis such as the ratio of water to oil, reaction time, and temperature, we can control the amount of fatty acids (acting as solvents and ligands) generated from the cooking oil. The method of gram-scale synthesis of R/G/B-CQDs with the structure of a core/chemical composition gradient shell by a single-step method using inexpensive and environmentally benign cooking oils, either fresh or waste, will greatly contribute to the field of full-color displays and solid-state lighting.