Sustainable materials for organic photovoltaic devices towards transient electronics in digital agriculture

With the growing demand for sustainable energy solutions, particularly for energy supply in transient sensor systems, this study focused on the introduction of environmentaly friendly materials for organic photovoltaics (OPV) and assessment of their key photovoltaic parameters. Regenerated cellulose (RC), gelatin and propylene glycol (PGG) as a biodegradable alternative for fossil-based PET film called as substrate, and soil-compatible carbon paste (SCP) replacing evaporated metal electrode were assessed for electronics. The investigated aspects included current-voltage characteristics, leakage current, and cell efficiency under LED illumination at 1000 lx—relevant for IoT applications. Both: commercial and the newly developed OPV components were then analyzed in terms of microstructure, water solubility, and layer integration. Results show that RC can serve as a promising alternative substrate for OPV achieving a power conversion efficiency (PCE) of 15.88%, and the electrical properties of OPVs with developed SCP were significantly higher compared to commercial carbon paste (CP). SEM analysis confirmed good adhesion and uniformity between layers, supporting the mechanical integrity of the device. Despite high leakage currents in devices with printed SCP electrodes, further optimization can improve the overall device performance. The water solubility and environmental impact of OPV materials were assessed through conductivity and pH measurements over six months, revealing no significant changes in soil quality, with pH levels remaining within the plant-safe range of 6.0 to 7.5. The findings of this study demonstrate the performance of OPVs utilizing soil-compatible materials for transient electronics, towards the requirements of energy autonomous sensing in digital agriculture applications maintaining ecological integrity.