One-step microwave-assisted synthesis of water soluble CdSe quantum dots for white light-emitting diodes with excellent color rendering

Thiol-capped and red-emitting CdSe quantum dots (QDs) have been successfully synthesized in the air without hot-injection by one-step microwave method with friendly environment. The size and optical properties can be tuned by changing the reaction time, growth temperature, microwave power, and the Cd2+/Se molar ratio. The as-prepared CdSe QDs were mixed with the yellow-emitting YAG:Ce phosphor and coated onto a blue LED chip, a white LED with an excellent color rendering property was obtained. It exhibited a luminous efficiency of 67 lm/W and a Ra as high as 85, which is acceptable for general lighting. It indicates that the combination of the phosphor and QD in LEDs should be a good solution to obtain white light sources with high color rendering.

The schematic diagram for synthesis of CdSe QDs (the experimental procedure was from step (a) to step (e)). CdSe QDs capped with thiol ligands were successfully synthesized through the interaction of cadmium thiol complexes with Se2− by a simple one-step approach which does not require the separated preparation of Se precursor (Na2SeSO3) under the protection of inert atmosphere.Figure optionsDownload as PowerPoint slideHighlights
► CdSe QDs were synthesized by a simple one-step microwave-assisted approach.
► The size and optical property can be tuned by controlling preparation condition.
► A WLED was fabricated with a mixture of yellow YAG:Ce3+ and red-emitting CdSe QDs.
► The WLED exhibited a luminous efficiency of 67 lm/W and a Ra as high as 85.
► The optical properties of the obtained WLED are acceptable for general lighting.