Highly efficient long thin-film fiber-shaped dye sensitized solar cells based on a fully organic sensitizer

In light of the ever-growing demand of modern electronics for wearable integrated optoelectronic devices, Fiber-shaped Dye-Sensitized Solar Cells (FDSSCs) have gained increasing interest over the last years as suitable energy production systems for the development of the next generation of smart products. To fulfill the wearable concept, it is important to design long and flexible thin-film FDSSCs capable of adapting to curved surfaces such as the human body. In this study, for the first time, several key parameters towards the optimization of long and flexible FDSSCs based on inexpensive TiO2 as photoanode material and a fully organic thiazolo [5,4-d]thiazole-based sensitizer (TTZ5) were studied. First, the influence of photoanode thickness on photovoltaic performance was evaluated in 3.5 cm-long devices, for which an optimal thickness of 10 µm was identified, obtaining a maximum PCE of 1.57 ± 0.15%. Long (10 cm) complete FDSSCs were then fabricated, using thin layer photoanodes of about 5 µm which were instead found to be the optimal choice for such devices. The as-obtained FDSSCs based on TTZ5 possess dimensions appealing for future applications while also delivering a remarkable PCE of 1.23 ± 0.04%, thus paving the way for further optimization of thin-film flexible long FDSSCs based on organic sensitizers.