Dye-sensitized solar cells (DSSCs), together with organic and perovskite cells, represents the third generation of photovoltaic solar cells. DSSCs are characterized by reasonable fabrication costs, low weight, and relatively high conversion efficiency in diffuse radiation with good absorption regardless of the angle of incidence of the sun's rays. However, there is still a great need to improve the working parameters of dye-sensitized solar cells. The dye sensitizer is one of the crucial components that strongly affects the performance of DSSC by extending the range of light absorption. The objective of this study is to report the influence of photoanode immersion time on the working parameters of catechol-based dye-sensitized cells. According to theoretical investigation, catechol is a metal-free organic dye that can be implemented in DSSC. The DSSC assemblies were carefully fabricated in a sandwich way with the use of TiO2-based photoanodes, Pt counter electrodes, and iodide/triiodide electrolytes. A relationship between photoanode sensitization time and DSSC efficiency was established and then optimized. The optical and electrical measurements were carried out; the dye/TiO2 complexes were characterized by UV–Vis spectrophotometric analysis, while the prepared cells were tested using a solar light simulator under standard test conditions (STC). The role of the back reflector layer made of BaSO4 on conversion efficiency was also investigated.