A Hand-Held Solar Cell Inspired by Nature

Photosystem I (PSI) is an integral membrane protein that plays an important role in conversion of solar energy to chemical energy in photosynthesis. We have developed a biomimetic device that utilizes the energy conversion properties of PSI. Using pre-developed techniques, we are able to extract the protein from the thylakoid membrane of spinach leaf cells. Vacuum evaporation of the PSI rich solution allows the deposition of a thick PSI multilayer onto a tailored surface. A self-assembling monolayer (SAM) is used to link PSI to a gold electrode which serves as the platform for the device. Through the use of the flexible polymer PDMS and a transparent ITO/Cu coated glass anode, a portable photoelectrochemical cell has been constructed. The mediators DCIP and sodium ascorbate allow for charge transfer between the PSI and the anode. The device is able to achieve a sustained light-induced current of ~2ľA/cm^2.