Solar cells are characterised by two fundamental features; they produce a direct electrical current during periods of illumination, and the current drops to zero when the illumination ceases. Now, a UK-based research group have developed a novel protein-based photoelectrochemical cell that produces a direct current during periods of continuous illumination but a novel alternating current under discontinuous illumination. The source of both types of photocurrent is a photosynthetic protein that separates charge in a highly efficient manner and can act as a charge accumulation device.

In their work, the team examine the effect of different electrode materials on the amplitude and profiles of the forward and reverse parts of this alternating current, and show that a near-symmetrical AC can be obtained by employing a superhydrophobic electrode formed from multi-walled carbon nanotubes. The ability to produce a variety of current profiles from biohybrid cells of this type lends itself to potential applications beyond pure photovoltaics.