Abstract

Abstract 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.