Deconvolution of photoluminescence spectra and electronic transition in carbon dots nanoparticles from microcrystalline cellulose

Abstract

Carbon dots (CDs) are nanomaterials with promising applications in several areas such as optoelectronics and biomedicine due to their low toxicity and strong luminescence intensity. Understanding the emission and bandwidth of the fluorescence spectrum is still a challenge in the scientific community due to the dependence of emission on the excitation wavelength. In this work, the photoluminescence properties of carbon dots obtained from microcrystalline cellulose (MCC) were studied. The optical properties were studied through measurements of photoluminescence (PL), photoluminescence excitation (PLE), and absorption. Systematic adjustments were made through Gaussian deconvolution of the PL spectrums and the coupling between electronic states was analyzed through PLE and optical absorption measurements. From the Gaussian adjustments, bandwidth values of ∼25 nm and ∼100 nm were found for the emission associated with the core and the surface states respectively, these values are consistent with the bandwidth of the PLE spectra with tuned detection in these states. As evidenced by the results, there are contributions from the core and surface functional groups in the luminescence emission of CDs. Furthermore, with recent analyzes that attribute the radiative emission of CDs only to the surface trap states, we observed that the core present emission and absorption of light for samples with specific pH and reaction times. These results should contribute to the understanding of the electronic transitions of CDs for applications related to the luminescent optical properties of these nanomaterials.