Efficiency Improvement on Indium Tin Oxide Films for Dye-Sensitized Solar Cell Using Oxygen Plasma by Bias-Magnetron RF Sputtering Process

Dye-sensitized solar cells (DSSCs) are among the most widely studied thin-film solar cells
because of their cost-effectiveness, low toxicity, and simple fabrication method. However, there
is still much scope for replacing current DSSC materials due to their high cost, low volume, and
lack of long-term stability. Accordingly, indium tin oxide (ITO)-nanorod films were fabricated by
electron (E)-beam evaporation using the glancing angle deposition method in this study. Then, the
ITO-nanorod was treated with oxygen plasma via a bias-magnetron radio-frequency (RF) sputtering
process to improve the efficiency of DSSCs under a varying gas flow rate of 20, 40, 60, 80, and
100 sccm. The field emission scanning electron microscopy (FE-SEM) investigation of the ITO film
structure revealed that the obtained nanorod structures have slightly different diameters. At the same
time, an increase in the oxygen flow rate resulted in a rougher film surface structure. In this, the
lower sheet resistance was received because of rougher morphology. When comparing the DSSCs
efficiency (η) test results, we found that at a gas flow rate of 100 sccm, the highest efficiency value
showed 9.5%. On the other hand, the ITO-nanorod without plasma treatment exhibited the lowest η.
Hence, plasma technology can be practically applied to improve the η of DSSC devices. This study
will be a prototype of a highly advanced solar cell manufacturing method for the solar cell industry