Transparent Phase Change Materials for Solar-Cell Front-Encapsulation Combining High Transmittance and Passive Thermal Management.

Solid-solid phase change materials (SS-PCMs) are promising candidates for solar-cell thermal management because they can buffer heat accumulation through latent heat storage. However, their practical application is still hindered by poor optical transmittance and insufficient mechanical stability. In this work, we present a robust material design strategy to fabricate highly transparent and morphologically stable phase change films via the synergistic crosslinking polymerization of octadecyl acrylate with tailored diacrylate crosslinkers. Measured at 20 °C (below the transition point), the optimized phase change films demonstrate an exceptional visible light transmittance of up to 96.8% at 700 nm. Systematic investigations reveal that the optical, mechanical (2.8-11.3 MPa), and thermal storage (43-86 J/g) properties can be precisely engineered by modulating the crosslinker architecture and density. Furthermore, integrated application tests as front-encapsulants for monocrystalline silicon solar cells demonstrate that these phase change films provide superior passive thermal management, effectively suppressing heat-induced efficiency degradation. Under continuous solar irradiation, the PCM-encapsulated system extended the temperature-rise delay by 940 s compared to conventional covers, maintaining significantly more stable photovoltaic performance. This work establishes a versatile multifunctional platform for the next generation of photothermal-cooperative energy management systems.