Photocurrent Generation in Artificial Light-Harvesting Protein Matrices

Light-harvesting is at the heart of photocurrent generation devices, and it is also one of the most important natural phenomena of which photosynthesis is an example. Inspired by natural light-harvesting complexes, we present here a synthetic and artificial solid-state protein-based matrix that is molecularly doped with natural light-harvesting chlorophyll molecules. Such protein matrices are capable of photocurrent generation over a wide range of wavelengths in a source-drain configuration. We show that the photocurrent generation shows a switchable (flipping) behavior when (1) the magnitude of the applied bias is changed, (2) the location of the irradiated area is changed with respect to the electrodes, and (3) a gradient doping, enabled by the facile molecular doping approach, is formed. Finally, the synthetic artificial nature of the protein matrix allows the exploration of several light-harvesting cofactors not used in natural systems, where we further show photocurrent generation by doped, metal-free porphyrins.