Síntese e caracterização de Nb₂O₅, para aplicação como material transportador de elétrons em células solares sensibilizadas por corante

Abstract

With the increase in energy demand, coupled with population growth, renewable energy sources emerge as an excellent alternative. Among the developed photovoltaic technologies, dye-sensitized solar cells (DSSC) have gained prominence in systems that utilize solar energy. DSSCs consist of an anode, an electrolyte, and a cathode. In the fabrication of anodic interfaces, various materials can be used, such as Nb₂O₅. This work aims to investigate the synthesis of niobium pentoxide (Nb₂O₅) by the Pechini method, followed by calcination at different temperatures (500 °C, 600 °C, and 700 °C) to evaluate its structural, morphological, and electrochemical properties as a photoanode material in DSSCs. MEV and DRX analyses revealed that calcination at 600 °C produced a material with optimized particle size (642.17 ± 37 nm) and orthorhombic crystalline structure, favoring electron transport and dye adsorption. The crystallite size estimation showed proportionality with the increase in sintering temperature; however, the bandgap did not change with the effect of the temperatures used (2.97 eV). Electrochemical characterization, including open-circuit potential, J-V curves, and impedance spectroscopy, indicated that the sample at 600 °C exhibited superior photovoltaic performance, with a current density of 4.23 mA cm⁻² and a potential of 0.694 V, achieving an energy conversion efficiency of 1.39% and an electron lifetime of 0.159 s. These results suggest that Nb₂O₅, under controlled calcination conditions, can act as a promising alternative to TiO₂ in DSSC applications.