Ultrabroad-emitting CuGaS2/ZnS quantum dots for high-color-quality white light-emitting diodes

A cost-effective CuGaS 2 /ZnS QD synthesis achieves ultrabroadband white emission with a FWHM of 257.9 nm and PLQY of 34.5%. • Cu/Ga ratio and coating temperature regulate defect trapping and carrier relaxation for tunable ultrabroadband emission. • QD-based pc-WLEDs deliver high-quality white light with CIE (0.348, 0.359), CRI of 94.9, CCT of 4915 K, and EQE of 23.8%. Colloidal I-III-VI QDs have emerged as promising candidates for environmentally benign next-generation illumination owing to their facile synthesis, low toxicity, and exceptional optoelectronic properties, yet achieving high-quality white-light emission remains challenging. Herein, we report a cost-effective and sustainable synthesis of CuGaS 2 /ZnS QDs exhibiting ultrabroadband white-light emission with a full width at half maximum (FWHM) of 257.9 nm and a robust photoluminescence quantum yield (PLQY) of 34.5%. Mechanistic investigations reveal that Cu/Ga compositional engineering regulates Cu vacancies, suppressing intrinsic nonradiative recombination while stabilizing shallow-defect-related high-energy emission. Concurrently, temperature-dependent shell growth may regulate interfacial cation redistribution and defect configurations, thereby modulating cation-disorder-associated localized STE-like states, contributing to long-lived low-energy emissions. Through the synergistic suppression of nonradiative recombination and modulation of carrier relaxation and trapping dynamics, the coating temperature redistributes carrier populations between intrinsic and defect-related states, enabling stable dual emission and highly tunable ultrabroadband emission across the entire visible spectrum. Furthermore, phosphor-converted white light-emitting diodes (pc-WLEDs) fabricated by integrating CuGaS 2 /ZnS QDs with red-emitting CuInS 2 /ZnS QDs deliver high-fidelity white-light emission with a color rendering index (CRI) of 94.9 and an external quantum efficiency of 23.8%, closely reproducing the spectral characteristics of natural sunlight and highlighting their promise for solid-state lighting and display technologies. Download: Download high-res image (123KB) Download: Download full-size image