Facile Room-Temperature Synthesis of High-Chemical-Stability Nitrogen-Doped Graphene Quantum Dot/CsPbBr3 Composite

Inorganic perovskite (CsPbX3) nanocrystals (IPNCs) have emerged as a class of optoelectronic material because of their notable properties. However, CsPbX3 is sensitive to polar substances and thermal treatment, both of which lead to severe degradation in photoluminescence (PL) properties. In this work, nitrogen-doped graphene quantum dots (N-GQDs) were applied as the ligand and stabilizer for synthesizing N-GQD/CsPbBr3 nanocomposites by the antisolvent method at room temperature. We found that the phase purity, grain size, and luminescence properties of the composite can be well controlled by the ligand effect of N-GQDs. Moreover, the N-GQD/CsPbBr3 composite exhibits excellent thermal stability, retaining approximately 40% of its original photoluminescence intensity after heating at 100 degrees C for 0.5 h, whereas pristine CsPbBr3 retains 4%. Furthermore, the composite displays a higher chemical stability in a polar environment. More impressively, we found that this composite is stable even in water (whereas pristine CsPbBr3 is damaged in several minutes) and retains approximately 93% of its original photoluminescence quantum yield value even after a week. When combined with P25 TiO2, the composite exhibits superior photocatalytic properties in aqueous solution, showing a rhodamine B degradation rate 14 times that of pure TiO2. These measurement results indicated that the stability and electron transportation of CsPbBr3 NCs be significantly improved by compositing with N-GQDs, opening a wide application range in advanced optoelectronics and photocatalysis.