Yellow‐Emissive Carbon Dots with High Solid‐State Photoluminescence

Abstract Carbon dots (CDs) present an enticing prospect for a variety of optical applications relying on their high photoluminescence (PL) quantum yield (QY). Herein, the synthesis, optical properties, structural characterizations, density‐functional theory (DFT) calculations, and potential applications of yellow‐emissive CDs (Y‐CDs) with ultra‐high PL QY are reported. Solvothermal treatment of citric acid and urea in toluene, followed by column chromatography, produces Y‐CDs exhibiting excitation‐independent PL emission at 553 nm with a high solution PL QY of 92%. A variety of optical and structural characterizations and DFT theoretical calculations are implemented to confirm the general structure and fluorescence origin of Y‐CDs, conjugated sp 2 ‐carbon domains (fused rings) with edge groups. Significantly, transparent Y‐CDs/acrylic resin films with strong solid‐state emissions are fabricated. The Y‐CD films exhibit a high fluorescence with PL QY of 98%, good PL stability (no PL variation under continuous irradiation for 180 h), and large Stokes shift (129 nm). The potential applications of Y‐CDs for luminescent solar concentrators as well as yellow phosphors for lighting are also demonstrated. These findings thus promote the development of high‐performance CDs and their optoelectronic applications.