Since their introduction, dye-sensitized solar cells (DSCs) have achieved huge success at a laboratory level. Recently, research is concentrated to visualize large DSC modules at the commercial platform. In that aspect, we have tested structurally simple porphyrin-based dye SK6 and anthracene-based dye CW10 for DSCs application under simulated 1 sun (AM 1.5G) and indoor light sources. These two dyes can be easily synthesized and yet are efficient with cell performances of ca. 5.42% and ca. 5.75% (without coadsorbent/additive) for SK6 and CW10, respectively, under AM 1.5G illumination. The power conversion efficiency (PCE) of SK6 reported in this work is the highest ever reported; this is achieved by optimizing the adsorption of SK6 on TiO2 photoanode using the most suitable solvent and immersion period. Cosensitization of SK6 with CW10 on TiO2 surface has boosted cell performance further and achieved PCE of ca. 6.31% under AM 1.5G illumination. Charge-transfer properties of individual and cosensitized devices at TiO2/dye/electrolyte interface were examined via electrochemical impedance spectroscopy. To understand the cell performances under ambient light conditions, we soaked individual and cosensitized devices under T5 and light-emitting diode light sources in the range of 300-6000 lx. The PCE of ca. 22.91% under T5 light (6000 lx) with JSC = 0.883 mA cm-2, VOC = 0.646 V, and FF = 0.749 was noted for the cosensitized device, which equals a power output of 426 μW cm-2. These results reveal that DSCs made of structurally simple dyes performed efficiently under both 1 sun (AM 1.5G) and indoor light conditions, which is undoubtedly a significant achievement when it comes to a choice of commercial application.
Keywords: cosensitization; dim light; dye-sensitized solar cells; organic dye; porphyrin.