# Photon‐to‐Heat Energy Harvesting Fluorescent Protein Coatings for Thermoelectrics

## TL;DR

This paper introduces fluorescent protein coatings that convert light into heat to improve thermoelectric generators for sustainable energy harvesting.

## Contribution

The novel use of fluorescent proteins in photothermal coatings for thermoelectric energy harvesting is introduced.

## Key findings

- FP coatings achieved photothermal efficiencies of up to 48%.
- Temperatures of 40–60°C were reached under LED illumination.
- A power gain of up to 232 µW cm−2 was achieved using white LED.

## Abstract

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.

Fluorescent proteins (FPs) are used in light‐absorbing coatings on thermoelectric generators (TEGs) to convert light into heat and generate electricity. By tuning the properties of FP‐doped polymer matrices, photothermal efficiencies of up to 48% have been achieved. This biohybrid strategy offers a sustainable approach for powering low‐energy devices using customizable protein‐based photon‐to‐heat conversion materials.