Silver ants-inspired flexible photonic architectures with improved transparency and heat radiation for photovoltaic devices

Abstract

Silver ants forage at extremely high environmental temperatures, the hairs of which play a crucial role in reducing the body temperature via enhanced optical reflection and radiative heat dissipation as a passive daytime radiative cooler. Inspired by the hierarchical feature structure of the hairs, we fabricated the flexible photonic architectures (FPA) on polydimethylsiloxane (PDMS). With some modification to the feature structure, the FPA-PDMS exhibited not only a large emittance in the mid-infrared spectral range, comparable with that of state-of-the-art thermal emitters, but also the record-high transmittance and haze in the visible and near-infrared range, which would be particularly appealing to photovoltaic devices for maximizing sunlight absorption and minimizing parasitic heat. The ease of application of the FPA-PDMS was demonstrated in both emerging perovskite and mature commercial crystalline silicon solar cells, where the FPA-PDMS was electrostatically attached to their glass superstrates or covers and the improvements in photovoltaic characteristics as a result of enhanced light harvesting were confirmed through laboratory measurements. Though the synergetic effects of the improved transparency and heat radiation brought by the FPA-PDMS need to be characterized outdoors in the future, these findings pave the way for suppressing optical and thermal losses simultaneously in opto-electric-thermal coupled devices through learning sophistically evolved photonic architectures from nature.