Efficient Passive Cooling for Photovoltaic Cells via Self‐Hygroscopic Polyvinyl Alcohol/Graphene Films

ABSTRACT Photovoltaic (PV) technology plays a pivotal role in energy transformation processes, especially for sustainable energy systems. However, the conversion efficiency of the PV cells is adversely affected by increasing temperature, leading to a reduction in their overall performance. In this study, a self‐hygroscopic polyvinyl alcohol/graphene (SPG) cooling film, comprising a graphene layer and a polyvinyl alcohol (PVA) hydrogel layer with lithium bromide (LiBr), is introduced to passively reduce the working temperature of the PV cells. The graphene layer, as a heat‐conducting layer, can efficiently conduct heat from the heat source to the self‐hygroscopic PVA hydrogel layer used as an evaporation cooling layer. In addition, the introduction of LiBr endows the PVA hydrogel with an excellent self‐hygroscopic property. The SPG cooling film demonstrates an outstanding cooling performance under the synergistic effect of the graphene film and the self‐hygroscopic PVA hydrogel. In the outdoor experiments, the SPG cooling film can reduce the temperature of the PV cells by 20.6°C and increase its average output power from 74 to 93 W/m 2 , about a 25.7% increase. This cooling film demonstrates significant potential for enhancing cooling performance in electronic devices and could be widely used in the thermal management of PV cells.