A near-ideal color rendering white solid-state lighting device copackaged with two color-separated Cu–X–S (X = Ga, In) quantum dot emitters

Abstract

I–III–VI chalcogenide quantum dots (QDs) are regarded as the most promising downconverters for the fabrication of high-efficiency, high-color rendering solid-state lighting devices, particularly enabled by their exceptional photoluminescence (PL) quantum yields (QYs) along with substantially Stokes-shifted, broad PL characters. In this work, we first synthesize highly efficient green Cu–Ga–S (CGS) and red Cu–In–S (CIS) QDs, having PL QYs of 85 and 83%, respectively, after elaborate ZnS shelling. Then, these two QD emitters that are well color-separated are simply copackaged in a single blue LED chip for the fabrication of tricolored white QD-light-emitting diodes (QD-LEDs). A series of white QD-LEDs with this novel QD combination are prepared by varying the weight ratio of the two QDs loaded. A QD-LED with an optimal weight ratio between CGS and CIS QDs produces a spectrally well-balanced tricolored white electroluminescence, possessing not only near-ideal color rendering index values of 94–97 but high luminous efficacies of 43.1–68.8 lm W⁻¹, depending on the driving current.