Optical Shading Induces an In-Plane Potential Gradient in a Semiartificial Photosynthetic System Bringing Photoelectric Synergy

Semiartificial photosynthetic systems have opened up new avenues for harvesting solar energy using natural photosynthetic materials in combination with synthetic components. This work reports a new, semiartificial system for solar energy conversion that synergistically combines photoreactions in a purple bacterial photosynthetic membrane with those in three types of transition metal–semiconductor Schottky junctions. A transparent film of a common transition metal interfaced with an n-doped silicon semiconductor exhibits an in-plane potential gradient when a light-penetration variance is established on its surface by optical shading of photoabsorbing photosynthetic membranes. The in-plane potential gradients (0.08–0.3 V) enable a directional charge transport between the synthetic and natural photoelectric systems, which is further enhanced in a device setting by a biocompatible thixotropic gel electrolyte that permeates the membrane multilayer, facilitating a strong and steady photoelectric current as high as 1.3 mA cm⁻², the highest achieved so far with any anoxygenic photosynthetic system.