Hybrid solar photovoltaic conversion and water desalination via quad-band fano-resonant optical coatings and superwicking cooling

Hybrid Photovoltaic/Thermal (HPT) systems simultaneously convert solar energy into electrical power and thermal energy. These systems are attractive as they enable the thermal management of PV cells to maintain optimal operating temperatures and maximize the overall solar energy conversion. Despite their advantages, HPT systems have been limited to storing solar energy in the form of heat or simple water/space heating, thus restricting the broader application scope of HPT systems, particularly in regions with abundant solar energy. Here, we introduce a device that expands the scope of HPT applications by realizing a hybrid PV/ water desalination system, achieved through the integration of a Fano-resonant optical coating (FROC) onto a silicon substrate, which is turned superwicking via femtosecond laser surface patterning. This configuration allows a single-junction amorphous silicon solar cell to operate under higher solar concentrations with much less heat conversion, achieving a temperature reduction of 101 °C and an efficiency improvement of 335.7% compared to a standalone photovoltaic system under the solar concentration of 5. At the same time, the interfacial water desalination achieves a 2 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mi>kg</mml:mi> <mml:msup><mml:mrow><mml:mi>m</mml:mi></mml:mrow> <mml:mrow><mml:mo>-</mml:mo> <mml:mn>2</mml:mn></mml:mrow> </mml:msup> <mml:msup><mml:mrow><mml:mi>h</mml:mi></mml:mrow> <mml:mrow><mml:mo>-</mml:mo> <mml:mn>1</mml:mn></mml:mrow> </mml:msup> </mml:mrow> </mml:math> high evaporation rate. Over a 12-hour cycle, our HPT system showed a consistent performance, demonstrating a combined solar conversion efficiency of 79.6%. The demonstrated superwicking-FROC will pave the way for widespread adoption of HPT systems particularly in sunny coastal regions.