Hydrothermal synthesis of orange fluorescent carbon dots and their application in fabrication of warm WLEDs and fluorescent ink

Herein, we are reporting the synthesis of orange fluorescent carbon quantum dots (OFCDs) using o-phenylenediamine and semicarbazide by hydrothermal method and the synthesized OFCDs were applied for warm white light emitting diodes (WLEDs) and fluorescent ink applications. The fluorescence emission spectrum of OFCDs shows the emission maximum at 625 nm with an excitation wavelength of 540 nm. The quantum yield of OFCDs was calculated to be 23%. We have prepared warm WLED device by coating PVA-OFCDs polymer matrix on near UV LED light (λem: 420 nm). The OFCDs based warm WLED device exhibits chromaticity coordinate (0.42, 0.48), Colour Correlated Temperature (CCT) 2500 K and Color Rendering Index (CRI) value 82. We also prepared the highly stable fluorescent ink using the same PVA-OFCDs for security information encryption and anti-counterfeiting applications. This OFCDs and their WLEDs device would be an efficient one in optoelectronics and forensic fields.