Effects of nitrogen doping on the optical properties of carbon quantum dots

In this study, fluorescent carbon dots were prepared by the hydrothermal process and analysed the effect of nitrogen doping on the optical responses of the material. Doping introduces an excitation independent photoluminescence peak in the red region along with the excitation dependent shorter wavelength emission. The longer wavelength absorption and emission could arise from the modifications in the surface states which experimentally observed from the FTIR spectra. Time-resolved measurements indicate that the carrier lifetime delayed due to the doping. The modifications of the carboxyl and amine groups in the carbon dots introduce the considerable changes in the photophysics of nitrogen doped dots.