Realization of Narrow-Bandwidth Cu-Ga-S-Based Quantum Dots with Controllable Luminescence

Recently, I-III-VI type quantum dots (QDs) have attracted considerable attention in display technology due to their large-scale tunable emission and environmentally friendly characteristics. However, within this family, narrow-bandwidth Cu-based QDs have rarely been reported. Herein, the synthesis of narrow-bandwidth blue-emitting Cu-Ga-S (CGS)-based QDs is reported by a hot-injection method for the first time, boasting a narrow full width at half-maximum (FWHM) of 29 nm, closely approaching that of traditional Cd-based QDs. Through precisely controlling the temperature of nucleation stage, CGS-based QDs showcase a representative blue emission at 475 nm, featuring the narrowest FWHM and a photoluminescence quantum yield (PLQY) of 32%. Besides, the femtosecond transient fluorescence (fs-TA) characterization indicates that the narrow-bandwidth luminescence is attributed to band-to-hole recombination rather than donor-acceptor pair (DAP) recombination. The work opens a new avenue for narrow-bandwidth I-III-VI QDs, offering increased potential for applications in blue-light-emitting devices.