Efficiency enhancement of low-cost metal free dye sensitized solar cells via non-thermal atmospheric pressure plasma surface treatment

Dye sensitized solar cells (DSSC) are an attractive third-generation photovoltaic technology particularly promising for operation under diffuse and lower light conditions. However, high costs of the precious metals used for sensitizing dyes and low charge generation capability parameters limit the utility of DSSCs in comparison to conventional silicon solar cells. In this study, tin oxide (SnO2) photoelectrodes are treated with non-thermal atmospheric pressure plasmas to enhance photovoltaic performance. The effects of nitrogen and argon plasma surface treatment of photoanodes on the efficiency enhancement of DSSCs are systematically investigated by fabricating solar cells using pristine SnO2 and plasma-treated photoanodes. Solar cells made with Eosin Y sensitized pristine SnO2 photoanode exhibited a short circuit current density (JSC) of 1.03 mA cm−2 and an overall power conversion efficiency (PCE) of 0.30% whereas solar cells made with nitrogen plasma treated photoanode exhibited a JSC of 6.20 mA cm−2 and an overall PCE of 1.53% (4 times enhancement) under the same illumination of 100 mW cm−2 (AM 1.5). The efficiency of the solar cells fabricated with Ar plasma treated SnO2 photoanodes also showed an enhanced power conversion efficiency. Further characterizations revealed that the surface plasma treatments increased the surface roughness of the photoanodes. Plasma treatment led to the incorporation of nitrogen species and removal of surface impurities resulting in an increase in dye adsorption in the photoanode and hence the enhancement in the efficiency of the DSSC. This study demonstrated a one-pot treatment method for efficiency enhancement which could be used in various applications such as photovoltaic, catalytic and energy generation applications including DSSCs, thin-film solar cells, perovskite solar cells, gas sensing, bio-sensing, supercapacitors, Li-ion batteries and others.</p