Synergistic optical and thermal management for solar water and electricity co-generation via a front-side coupling strategy

Co-generation of fresh water and electricity from solar energy offers a sustainable pathway to global water and energy challenges. Here, we report a high-performance solar-driven water-electricity co-generator integrating a front-side coupling (FSC) strategy, where a precisely engineered thin water film on the front surface of photovoltaic cells enables synergistic optical-thermal regulation. A current loss model coupled with external quantum efficiency analysis predicts an optimal water film thickness of 2 mm, enabling an evaporation rate of 4.27 kg m⁻² h⁻¹ and a solar-to-electricity conversion efficiency of 19.1% under 1 sun using a 9-stage evaporator. Outdoor experiments further demonstrate the effectiveness of the FSC strategy, achieving relative enhancements of 18% in evaporation rate and 46% in electricity conversion efficiency compared to the conventional back-side coupling approach. These findings highlight the potential of the FSC strategy to advance scalable, efficient, and integrated solar-driven solutions for water and energy needs.