Knocking the Stability of Solar Cells with Fluorescent Protein Donors upon Rationalizing Design, Integration, and Mechanism

Abstract

Though photon‐induced electron donor features of fluorescent proteins (FPs) in solution suggest them as excellent photosensitizers, their poor stability upon device fabrication/operation is the today's frontier. This relates to their immediate denaturation in water‐free/less environments: inorganic/organic device interfaces and/or organic solvent surroundings. This study provides a fresh solution with a family of hybrid FPs, in which the peripheral carboxylic groups of archetypal FPs ‐superfolder green fluorescent protein (sfGFP) and mCherry‐ are transformed into alkoxysilane groups, enabling a straightforward integration with surprising stabilities over months in devices – arbitrary n/p‐type semiconducting metal oxide/FP/organic‐solvent electrolyte interfaces – attributed to the formation of an ion‐silica shell around the FP. This further allowed to understand the charge injection mechanism applying steady‐state/time‐resolved spectroscopy on different FP‐variants with key single‐point aromatic amino acid mutations at the chromophore nearest, revealing the electron‐donor hopping pathway via the initial loop of the strand β7. Finally, devices with state‐of‐the‐art solar‐to‐energy conversion efficiencies that are stable >2,000 h under operation nicely outperform the prior‐art stability of a few seconds/minutes in FP‐based solar cells. Hence, this work solves the integration/stability issues which blocking the application of FP‐based sensitizer, as well provides a solid understanding of their photo‐induced electron transfer mechanism.