Transition-metal dichalcogenides like tungsten disulfide (WS 2 ) are luminescent but still bear low quantum yields and hardly meet the requirement of practical applications. Here, we developed a hot-injection method to prepare highly luminescent WS 2 quantum dots with tunable particle size in a noncoordinating solvent, some that are even smaller than its Bohr radius. The as-synthesized WS 2 quantum dots exhibit a narrow size distribution and a high photoluminescence quantum yield of 32%, the highest record compared to the known reports. The WS 2 quantum dot layer was employed to fabricate white light-emitting diodes with a maximum brightness of 507 cd/m 2 , adjustable color temperatures from 4100 to 10 000 K, and excellent color rendering index of 91. These results confirm the promising optoelectronic applications of WS 2 quantum dots.

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The liquid-type carbon dot-based LEDs exhibited the luminous efficiency of 44.36 lm W−1, which was 2.27 times higher than that of solid devices.