JAPANESE JOURNAL OF APPLIED PHYSICS, vol.64, no.12, 2025 (SCI-Expanded, Scopus)
Cellulose nanofiber (CNF) films were used as model biodegradable substrate for flexible organic solar cells. To form transparent conductive electrodes compatible with CNF, the conductivity of poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) films was enhanced by two methods: additive doping of a low-conductivity source and a fast drop-spin solvent treatment of a high-conductivity source. The additive process increased conductivity from 3.48 x 10(-4) to 4.57 S cm(-1), while the drop-spin treatment improved it from 360 to 518 S cm(-1). Organic solar cells fabricated on CNF/glass substrates with improved-PEDOT:PSS films exhibited clear photovoltaic response, demonstrating the feasibility of acid-free, vacuum-free processing for CNF-based devices.