(251h) Photosystem I Enhances the Efficiency of a Natural, Gel-Based Dye-Sensitized Solar Cell

The Photosystem I (PSI) protein complex is known to enhance bioelectrode performance for many liquid-based photoelectrochemical cells. However, liquid-based devices have disadvantages such as complex fabrication, low portability, the need for frequent electrolyte refills, and poor suitability for photoelectric devices. In this investigation, we design a natural, gel-based dye-sensitized solar cell that integrates PSI to improve device efficiency. An agarose hydrogel as the electrolyte media allows for simpler fabrication of more robust and practical solar cells while avoiding some limitations in liquid-based devices. TiO₂-coated FTO slides, dyed by blackberry anthocyanin, act as a photoanode while a film of PSI deposited onto copper comprises the cathode. Ascorbic acid (AscH) and 2,6-dichlorophenolindophenol (DCPIP) are the redox mediator couple, enabling PSI to produce excess oxidized species near the cathode to improve the performance of the cell. A comparison of device performance at low pH and neutral pH was performed to test the pH-dependent properties of the AscH/DCPIP couple. Devices at neutral pH performed better than those at lower pH. The PSI film enhanced photovoltage by 75 mV to a total photovoltage of 0.45 V per device and provided a mediator concentration-dependent photocurrent enhancement over non-PSI devices, reaching a maximum photocurrent density of ~200 μA/cm². The measured power conversion efficiencies for devices with and without PSI were 0.042% and 0.028%, respectively.