Desenvolvimento de células solares flexíveis baseadas em pontos quânticos de carbono

Abstract

Advances in energy generation technologies have driven several studies aimed at diversifying the energy matrix, since most energy generation comes from non-renewable materials. Solar cells are promising devices capable of converting electromagnetic energy into electrical energy in a clean and renewable way. Carbon quantum dots (CQDs) have emerged as a class of highly versatile nanomaterials that can be applied in various areas due to their low toxicity, high photoluminescence, and biocompatibility. These CQDs can be applied in biosensors, bioimaging, catalysis, light-emitting diodes, photodetectors, and solar cells. In photovoltaic energy, they are used as photoactive material in third-generation solar cells due to their ability to absorb light in the visible and ultraviolet spectrum. In this work, CQDs were obtained by solvothermal synthesis and subsequently characterized by Ultraviolet-Visible Spectroscopy (UV-Vis), Fourier Transform Infrared Spectroscopy (FTIR), RAMAN Spectroscopy, and Transmission Electron Microscopy (TEM). In addition, TiO2 was obtained by the Sol-Gel synthesis method and characterized by XRD. TEM images confirmed the presence and average size (10.04 nm) of the obtained CQDs. FTIR and Raman spectroscopy identified the main functional groups and type of carbon present in the CQDs. In the absorbance spectrum collected, two absorption regions were observed: 250-375 nm (π - π* transitions) and 376-705 nm (n - π*). The XRD results showed that the TiO2 obtained is polymorphic, containing the anatase and brookite phases, with fractions of 56.28 and 43.72%, respectively. According to the Debye-Sherrer equation, the size of the material's crystallites was approximately 13.5 ± 2.7 nm for the anatase phase, 22.5 ± 5.7 nm for the brookite phase, and 20.1 ± 6.4 nm for both phases. The photovoltaic devices were assembled and characterized, presenting efficiencies close to 0.60%.