Photon-to-Heat Energy Harvesting Fluorescent Protein Coatings for Thermoelectrics

Energy-related protein optoelectronics is an emerging field with interesting examples in photon manipulation in lighting devices, photon-induced electron transfer in photovoltaics, and H-transfer in moisture electrical generators. Here, this field is extended with the concept of photon-to-heat energy harvesting fluorescent protein (FP) coatings applied to thermoelectric generators (TEG). This device consists of a commercial TEG coated with a FP-polymer coating optimized in terms of i) the amount of a high-absorbing and low-emissive FP named E2-Crimson and ii) the thermal features of a mixture of the branched/linear polyethylene oxide matrix. With photothermal efficiencies of 48% the FP-coatings can reach temperatures between 40-60 °C under monochromatic (590 nm) and the white LED illumination sources. This results in a total power gain of up to 232 µW cm^-2 (white LED), highlighting the potential of FP-coatings in sustainable energy harvesting for low-power autonomous devices. Overall, this work provides the first stepping stone in protein-based photon-to-heat conversion materials, which promise easy-to-tune photothermal properties through the choice of the protein chromophore, the engineering of the protein scaffold, and the control of the protein-polymer interactions.