Bio-Based PEDOT: Nanocellulose Hybrids as Efficient Hole-Transport Layers for Photoelectrochemical Devices

Abstract

Developing sustainable hole-transport materials that can match the performance of conventional poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) remains a key challenge for environmentally compatible optoelectronic devices. In this work, nanocrystalline cellulose (NCC) is demonstrated as a renewable dopant and stabilizer for PEDOT, forming bio-based hybrids with competitive photoelectrochemical performance. Two crystalline allomorphs, NCC Type I and NCC Type II were compared as templates for aqueous oxidative polymerization of EDOT, producing stable dispersions of PEDOT nanoparticles (50–100 nm) electrostatically anchored to the NCC surface. Spectroscopic and thermal analyses revealed that the higher ester sulfate content and distinct morphology of NCC-II promoted enhanced polaron stabilization and 10–15% higher PEDOT incorporation compared to NCC-I. FTIR and UV–vis spectroscopy showed more pronounced polaronic bands for PEDOT:NCC-II hybrids, evidencing enhanced charge delocalization and doping. Optimal performance was achieved for the PEDOT:NCC-II (50:50) composition, which formed stable, conductive networks and served as an efficient hole-transport layer in poly(3-hexylthiophene)-based photoelectrochemical devices. These bio-based electrodes achieved photocurrent densities above 18 µA cm-2, matching or exceeding PEDOT:PSS reference, and maintained stable operation over 300 s of cycling (>10 light/dark cycles at 0.3 Hz) with reproducible ON/OFF photoresponse. These findings establish nanocellulose-doped PEDOT as a sustainable alternative for next-generation optoelectronic interfaces.