Photovoltaic Bacteriorhodopsin Graphene-Cellulose Composite Transducers

An organic photovoltaic transducer is fabricated by combining bacteriorhodopsin (bR) purple membranes with a graphene - carboxymethyl cellulose (G-CMC) dispersion and depositing the solution on an optically transparent indium tin oxide coated substrate. The G-CMC nanoparticles act as charge carriers between the stacks of high resistance bR purple membrane sheets. Once dried the exposed surface of the bR-GCMC transducer is coated with a conductive epoxy to create a sandwiched photocell. The measured photovoltaic response of the composite transducer is more than 3.2× the voltage generated by a bR-only transducer. Experiments also demonstrate that the electrical resistance is significantly reduced from several hundred k-Ohms (bR-only) to <; 20Ω (bR-G-CMC). The chemical synthesis, device fabrication, and experimental characterization of the bR-G-CMC transducer are discussed.