Síntese de Nb2O5 pelo Método Hidrotérmico Assistido por Micro-ondas para Utilização em Células Solares Sensibilizadas por Corante

Abstract

Solar energy is a promising source for meet energy challenges with less environmental impact. Dye-sensitized solar cells (DSSC) are considered an attractive, environmentally-friendly and cost-effective solar conversion technology. Niobium pentoxide (Nb2O5) is a suitable material for this type of device because it has good photocatalytic activity and is widely available. The objective of the present work was to synthesize niobium pentoxide through the microwave assisted hydrothermal method, as well as its characterization for DSSC application. Ammonium oxalate from niobium, distilled water and hydrogen peroxide were used to perform the synthesis. The obtained powder was submitted to different thermal treatments (500-800°C), studying the influence on the phase, shape and size, vibrational modes, energy absorption, besides band gap of the respective samples, through the characterization by Diffraction (XRD), Scanning Electron Microscopy (SEM), Electron Transmission Electron Microscopy (TEM), Raman Spectroscopy, Fourier Transform Infrared Spectroscopy (FTIR), Photoluminescence Spectrometry (PL) and Absorption Spectroscopy Ultraviolet-Visible (UV-Vis). The pseudohexagonal and orthorhombic phases were found, with particle size ranging from 7.3 to 32.6nm and band gap from 3.04 to 3.34 eV. DSSC cells were assembled with the method of deposition by Doctor Blade, with the samples of 90°C and 500°C submitted to sensitization with colorant N3 and the one of 700°C without the use of the dye. The photovoltaic parameters of open-circuit voltage (Voc) and short-circuit current density (Jsc) were evaluated. The JxV curves of the solar cell were generated by data provided by a Solar Ivium Technologies IviSUN Simulator with use of high density LED array. The DSSC presented different characteristics regarding current density and voltage, showing the possibility of different applications of the cells according to the required requirement, where the Nb2O5 cell at 90°C had 3,39 e 207,36 , at 500°C yielded 4,34 e 115,39 and that of 700°C without dye J 2,89 e 246,73 . The cells presented a photovoltaic response, demonstrating that Nb2O5 has a semiconductive potential, allowing the follow-up in the related searches, through cell optimization.