Donor-Acceptor Substituted Carbon Nitride Enables Efficient and Colorful Phosphors

Graphitic carbon nitride (g-CN) is a polymeric semiconductor with low-cost synthesis, adjustable structure, and excellent stability, which attracts great attention and is widely used as a photocatalyst. On the contrary, it isn't considered as a promising fluorescent material due to the inefficient radiative recombination of electron-hole pairs. Here, efficient and multicolor-emitting g-CN phosphors are presented by integrating donor-acceptor substituents in order to replace the expensive rare earth-based phosphors. By incorporating phenyl as a donor and benzonitrile as an acceptor, the aromatic groups enhance the structural rigidity of g-CN and improve the photoluminescence (PL) efficiency; meanwhile, the donor-acceptor extends the pi-conjugated system of g-CN, promotes the electron delocalization and results in tunable PL spectra. As a result, the donor-acceptor substituted g-CN materials exhibit blue to yellow light emission and reach a record photoluminescence quantum yield (PLQY) of 57%. A white light-emitting diode is fabricated by combining the modified g-CN phosphors and commercial 450 nm blue chips, which produce a bright white light emission with chromaticity coordinates of (0.34, 0.32). The findings provide a rational design for a high-performance g-CN emitter and highlight the potential applications of g-CN in optoelectronic devices and indoor lighting.