Transparent porphyrin-based hybrid films for spectral selective solar harvesting and energy generation

Abstract

Spectral-selectively solar harvest is achieved in designated frequency regions for photothermal energy generation. In this study, we have designed and synthesized porphyrin-based hybrids that typically exhibit two absorption peaks respectively near 400 nm (blue-violet) and 700 nm (NIR). To be able to tune the optical absorptions for more efficient solar harvest especially in the IR region, unique porphyrin hybrids are developed by incorporating another porphyrin compound such as phthalocyanine, and inorganic Fe3O4@Cu2-xS nanoparticles with different absorption characteristics. By controlling the ratio of the components, the hybrids exhibit gradual and consistent changes in the optical spectra, showing high spectral tunability. Transparent thin films of the hybrids are deposited on glass substrates and assembled in parallel for 3D solar harvesting in a cuboid photothermal generator. Solar light is able to pass through the multilayers of thin films, generating significant thermal heat on each one for enhanced energy density. The structural features of the hybrids are well correlated to the optical behaviors based on Raman studies. Also discussed is the operating mechanisms underlying the photothermal behaviors associated with the hybrid structures.