Effect of TiO2 Nanoparticle Layer and Dynamic Mechanisms on the Efficiency of Dye-Sensitized Solar Cells

Abstract

This study deals with the analysis of the internal electrochemical characteristics of dye-sensitized solar cells (DSSC) using as semiconductor titanium dioxide (TiO2). The built DSSC was characterized by electrochemical impedance spectroscopy. This allowed to identify the mechanisms of degradation and extrapolation in function of efficiency improvement and factors of the cell such as current, voltage, capacitance, and lifetime electron. DSSC using different ways for the depositions of TiO2 nanostructures were manufactured, characterized, and the performance modeled. The influence of nanostructure (nanotubes or thin films), solvents (acetonitrile or ionic liquid), and the effect of additives (Tbp or lithium) were studied. The best results were obtained with the combination of nanotubes, acetonitrile, and lithium. Photocurrent density of 11.092 mA·cm2, open-circuit photovoltage of 0.707 V, fill factor of 71.9, and efficiency of 5.6 were obtained with the combination mentioned above, achieving the best resistance to the recombination, electron lifetime, and length of electrons diffusion. Low viscosity is the main advantage of organic solvents, which permits good diffusion of ionic species in the electrolyte, promoting dye regeneration, and acceptable reaction rate in the counter-electrode, consequently a better efficiency of the DSSC can be obtained.