Crystalline-Induced Luminescence of Carbon Dots for the WLED and Fingerprint Recognition

It is profound to obtain simply carbon nanodots (CDots)-based solid-state fluorescent in photoelectric field. However, synthesizing such material is still faced with a challenge due to the serious quenching effect. Here, a microwave pyrolytic route is reported to rapidly synthesize sulfur (S) and nitrogen (N) co-doping CDots wrapped by the crystalline phthalate (CDots/PA). The results show that CDots/PA presents needle-like crystal to coat abundant cluster of CDots inside, after fully optimizing the preparation conditions. The solid state CDots/PA emits a dazzling fluorescence with the fluorescence quantum yield (FLQY) = 1 7 %, which is attributed to the formation of barrier from the crystal to avoid the aggregation of CDots. In addition, due to the co-doping of S and N elements, it also presents an orange–red light with a multipeak feature. The excellent photoluminescence (PL) property of CDots/PA gives it an advantage to fabricate light emitting diode (LED)/white light emitting diode (WLED) devices, which achieves an orange light with the correlated color temperature ( CCT ) = 1 8 1 0 K, color rendering index ( CRI ) = 5 9 and a warm-white light with the CCT ≈ 3700 K, CRI ≈ 82 at the Commission Internationale de L’Eclairage ( CIE ) = ( 0 . 4 3 , 0.40) combined with the commercial phosphors. Moreover, CDots/PA also shows an excellent recognition capacity in the application of detecting latent fingerprints, endowing such fluorescent nanomaterials broad prospect in the photoelectric industry.