Enhanced photocurrent generation in bacteriorhodopsin based bio-sensitized solar cells using gel electrolyte

High purity light sensitive photoactive protein Bacteriorhodopsin (BR) was isolated successfully via a simple two phase extraction technique (ATPS) as an alternate method for the tedious sucrose gradient ultracentrifugation procedure (SGU). Bio sensitized solar cells (BSSCs) were fabricated by the integration of BR into TiO2 (photo anode) with acetamide based gel electrolytes and platinum (photo cathode) as a counter electrode. The structural and photoelectrical behaviours of BR and BSSCs were analyzed by Atomic Force Microscopy, Raman spectroscopy, photocurrent and photovoltage (IV) measurement and electrochemical impedance spectroscopy. The short circuit photocurrent (Jsc) and photoelectric conversion efficiency (η) of acetamide based gel electrolyte (AG) (1.08mAcm(-2), 0.49%) are twice higher than that of traditional triiodide based liquid electrolyte (LE) (0.62mAcm(-2), 0.19%). Also, quasi-Fermi level and lifetime of photogenerated electrons in acetamide based gel electrolyte is about four times higher than that observed in traditional triiodide redox electrolyte. A comparison of the observed results with similar BSSCs made of other natural photoactive protein systems shows that BR as sensitizer has better photovoltaic performance. The enhanced photocurrent generation of the BSSC constructed in our study could be due to the interaction of BR with acetamide based modified poly(ethylene)oxide (PEO) gel electrolyte.