Passive superwicking interfacial evaporative cooling enables single-junction photovoltaic operation under 10× solar concentration

<h2>Summary</h2> Interfacial evaporation-based photovoltaic-thermal systems offer a promising solution for the global energy and water crisis by utilizing excess heat from photovoltaics for interfacial evaporation. However, previous designs faced two critical challenges: high thermal resistance from porous wicking materials and an insufficient water supply for stable operation under high solar concentrations. Here, we demonstrate an interfacial evaporation-based photovoltaic-thermal system that enables continuous operation under high solar concentrations by integrating a superwicking black metal heat-mass exchanger directly onto the photovoltaic backside. Superwicking black metal features open microcapillaries that rapidly pull a thin film of water across its surface, enabling low-resistance heat transfer and continuous evaporative cooling in high solar concentrations. Under a 10-sun optical concentration, our system produces 731 Wm⁻² electrical power and desalinates 10.1 kg m⁻² h⁻¹ seawater with zero liquid discharge. Additionally, the developed system can track the sun throughout the day to maximize solar radiance and desalination performance.