The Effect of Plasma Modification and CDCA Co-adsorption on the Dye Adsorption Capacity of TiO_₂ Photoanodes

Dye-sensitized solar cells (DSSCs) are third-generation photovoltaic devices that convert solar radiation into electrical energy. Due to their low cost and ease of fabrication, DSSCs have attracted extensive research interest. In this study, we aimed to enhance the power conversion efficiency (PCE) of dye-sensitized solar cells (DSSCs) with pure TiO<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">₂</inf> photoanodes by improving dye adsorption. Our research explored two distinct approaches, plasma surface modification and co-adsorbent optimization. In the first part, TiO<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">₂</inf> photoanodes were treated using oxygen–argon plasma under fixed duration and gas flow, while useing the 100W power to identify optimal surface modification conditions for enhanced dye adsorption. In the second part, the influence of chenodeoxycholic acid (CDCA) as a co-adsorbent was investigated by adding different concentrations (0.5 mM, 1.5 mM, 2.0 mM) to a 0.3 mM N719 dye solution. Results showed that 2.0 mM CDCA yielded the highest PCE, improving device performance from 4.8% to 5.5%. This study demonstrates that combining plasma treatment and optimal CDCA concentration significantly enhances dye adsorption and suppresses aggregation, providing a feasible strategy for developing high-efficiency DSSCs.