Attaining a wide photoluminescence Stokes-shift of carbon dots obtained from waste biomass

Owing to the tremendous physicochemical and quantum confinement characteristics of carbon quantum dots (CQDs), they have revealed exciting and essential visions in the field of energy conversion and energy storage. However, due to their low photoluminescence quantum yield (PLQY) and/or short Stokes-shift, limits their application in photovoltaic (PV). In this regard, a novel and cost-effective method was used to synthesize the CQDs using waste biomass. Furthermore, a comprehensive study was made to explore the applicability of the CQDs as photon downconverters/downshifters in PVs. The average size of the CQDs are 5.1, 4.4, and 3.9 nm for the synthesis temperature of 160, 180, and 200 ℃, respectively. The EDS analysis revealed that C, O, Mg, Na, Cl, and K are present in all the CQDs. The PL emission peak position is blue-shifted with the rise in the synthesis temperature. The Stokes-shift is reduced with a rise in the synthesis temperature. The highest Stokes-shift was obtained at excitation wavelength of 300 nm for CQDs synthesized at 160 ℃. The PLQY increased by 3.5 and 7.2-folds for the rise in the temperature from 160 to 180 and 200 ℃, respectively. The investigation revealed that the applicability of CQDs can be enriched via the selection of the synthesis parameters.