Synthesis of Mn-doped CuGaS2 quantum dots and their application as single downconverters for high-color rendering solid-state lighting devices

Photoluminescence (PL) of quantum dots (QDs) can be modulated by doping transition metal ions into them, yielding either only a dopant-related single PL band with an excitonic emission entirely quenched or multiple PL bands with a dopant-related PL superposed, depending on the host QD composition targeted. Herein, we attempt Mn doping into green-emitting CuGaS2 (CGS) QDs through surface adsorption and lattice diffusion strategy. The resulting Mn-doped, ZnS-shelled CGS or CGS: Mn/ZnS QDs exhibit two distinct PL bands associated with host QD defect and dopant emissions. The spectral ratio of such two PL components is facilely tunable by varying Mn concentration. A series of CGS: Mn/ZnS QDs possess high PL quantum yields in the range of 74-76% regardless of Mn concentration. Taking full advantage of the wide PL coverage of green-to-red and efficient absorption capability at the blue region of the present doped QDs, they are packaged as single downconverters with a blue light-emitting diode (LED) chip to fabricate a high-color rendering solid-state lighting device. Various electroluminescent characteristics of white QD-LED are evaluated as a function of QD doping concentration and input current and discussed in detail. (c) 2018 Optical Society of America under the terms of the OSA Open Access Publishing Agreement