Spectral broadening of Cu-In-Zn-S quantum dot color converters for high color rendering white lighting device

We report the synthesis of quaternay Cu-In-Zn-S (CIZS) core/ZnS shell quantum dots (QDs) that possess the emission wavelengths suitable as color converters for white light-emitting diode (LED) fabrication. For the demonstration of high color rendering white QD-LEDs enabled by a more complete white spectral coverage, the synthetic effort on CIZS QDs exhibiting the photoluminescence (PL) as broad as possible is made. The amount of 1-dodecanethiol (DDT) used in CIZS core synthesis is found to critically affect the spectral shape and consequent bandwidth of QD emission. The QD PL is systematically, progressively broadened with increasing DDT amount, achieving an unprecedented bandwidth up to ~240 nm. The CIZS/ZnS QDs that are synthesized with different DDT amounts are indiviually tested as color converters for the fabrication of white QD-LEDs and thier performance is compared. The resulting devices exhibit color rendering index (CRI) values in the range of 74-95, depending on CIZS/ZnS QDs used. This exceptional CRI of 95 is a record quantitiy obtainable by use of a single QD color converter.