Efficiency Enhancement of Biophotovoltaic Solid‐State Solar Cells

Biophotovoltaic solid‐state solar cells are new environmentally friendly solar cells inspired by photosynthesis phenomena. Photosystem I, a complex protein located in the chloroplast of the plant leaves that has a principal role in light absorption, is the most common light absorber used in biophotovoltaic solid‐state solar cells. Low efficiency and low current density are the main challenges in this kind of solar cell. Herein, to vacillate the motion of electrons and holes, carbon nanotubes and tyrosine are used as transfer layers and to increase light absorbance, a solution of Photosystem I with silver nanoparticles as an absorber layer is used. It is shown that the short circuit current density and the efficiency can be enhanced to 6.61 mA cm −2 and 0.83%, respectively which are the highest values for current density and efficiency reported for this kind of solar cell. These enhancements are due to the high electrical conductivity of carbon nanotubes, proper porosity of tyrosine, and the localized surface plasmon resonance of silver nanoparticles induced under light irradiation. The results can illuminate hopes and dreams for biophotovoltaic solid‐state solar cells with higher current density and higher efficiency.