A rational strategy for directly synthesizing strongly yellow solid-state fluorescent-emitting carbon nanodots composite microparticles by structure regulation

Carbon nanodots (CDs) have received huge attention of researchers due to their good optical properties. However, CDs generally suffer from severely fluorescence self-quenching once they are aggregated or in solid state, limitating their applications in light-emitting devices. In this work, we report a rational strategy for synthesis of yellow fluorescent carbon nanodots (Y-CDs)-based microparticles with a high solid-state photoluminescence quantum yield (32.02%). It is the first report on designing a lamellar structured matrix to disperse CDs to realize long-wavelength solid fluorescence. The matrix is confirmed as p-phenylenediamine dihydrochloride by X-ray diffraction (XRD). 3-glycidyloxypropyltrimethoxysilane (KH-560) acts as a bridge to connect CDs to the matrix based on epoxy-amine reaction and silane hydrolysis condensation for uniform dispersion of CDs and high solid-state luminescence can be easily achieved. Meanwhile, through adjusting the amount of KH-560, the morphology of Y-CDs-based microparticles can be controlled from cube to layered structure and the fluorescence intensity can be significantly improved. Importantly, the optimal Y-CDs particles can be combined with blue chips (450 nm) to fabricate high-performance white light-emitting diodes (WLEDs) without using commercial phosphor, and the constructed WLEDs exhibit a high color rendering index (CRI) of 84.2.