Flexible and Biodegradable Cellulose Counter‐Electrode in Aqueous‐Based Dye‐Sensitized Solar Cells

Sustainable fabrication of photovoltaic devices remains challenging due to the widespread use of non-renewable substrates and organic solvents. In this work, we investigate biodegradable cellulose-based substrates for flexible counter electrodes in aqueous dye-sensitized solar cells (DSSCs). Ethyl cellulose films prepared from different solvents were characterized in terms of rheology, mechanical flexibility, and biodegradability. The optimized formulation was coated with Ti/Au/Pt catalytic three-layer and integrated into aqueous DSSC devices. The resulting solar cells achieved a maximum power conversion efficiency of 1.06%, comparable to reference devices fabricated on glass substrates using the same architecture. These results demonstrate that biodegradable cellulose substrates can support functional photovoltaic devices, providing a promising pathway toward more sustainable optoelectronic technologies.