Simulation of Electron Diffusion Coefficient Interpretation on the Optimum Thickness of TiO2 Photoanode in Dye-Sensitized Solar Cell (DSSC)

DSSC is a natural dye-based organic solar cell composed of layers of semiconductor (photoanode), dye, electrolyte, and the counter electrode. The photoanode layer on DSSC acts as a dye binder and can pass on excited electrons to the electrode counter. This component is one of the keys to improve the DSSC performance. The TiO2 material has been used widely as a photoanode due to its high stability to light so that at its optimum thickness it can pass well the sunlight energy on the surface of the DSSC. When the sunlight energy impinges to DSSC for relatively long time, it can increase the working temperature. Theoretically, the increase in the working temperature of the DSSC causes an increase in the electron diffusion coefficient in the DSSC, thus affecting its performance. Therefore, the interpretation of an increase in the electron diffusion coefficient due to an increase in the thickness and working temperature in DSSC is essential to be studied. In this article, a simulation of the determination of the optimum thickness of TiO2 photoanode was carried out. We studied the effect of electron diffusion coefficient on the DSSC open voltage at the optimum thickness. The highest electron diffusion coefficient in this simulation was 9.65x10-3 cm2/s with current density of 0.0145 A/cm2, voltage of 0.3411 V, power of 0.0020 V·A/cm2, and efficiency of 2.000%. We found that the higher the electron diffusion coefficient, the open voltage of DSSC increased so that its performance also increased.