Keratin Film as Natural and Eco‐Friendly Support for Organic Optoelectronic Devices

Abstract This work describes the preparation of a novel substrate based on keratin extracted from wool and its application as potential support for solution‐processed organic solar cells. Optically transparent, free‐standing, and resistant keratin films are successfully prepared, starting from water solution, and characterized in terms of morphology, structure, thermal and mechanical properties. The effect of solvents and thermal annealing is also investigated in order to mimic and evaluate the impact of the processing conditions used for devices fabrication. Thermally annealed keratin films exhibit enhanced optical transparency (>87%) in the visible region of the spectrum, a transition from α‐helix to β‐sheet and turn structures, improved thermal stability and Young's modulus. The good transparency, flatness, and resistance of as‐cast substrates allow the successful preparation of organic solar cells. Photovoltaic performances similar to those reported for other natural/biobased supports are achieved, confirming the potential of keratin film as an alternative and promising support material for eco‐friendly, fully printable, sustainable, and inexpensive optoelectronic devices.