Synergistic Evaporative Cooling and Dual-Mode Luminescent Film for Photovoltaic Cooling and Spectral Harvesting

Passive cooling thermal management is crucial for addressing inevitable heating and inefficient heat dissipation in photovoltaic (PV) devices. Designing cooling systems with high transparency, solar conversion, and interfacial properties for diverse PV technologies remains challenging. This work develops a photoluminescent passive cooling film as a "front-surface" solution for silicon (Si) based solar cells, integrating passive evaporative cooling with spectral conversion. This environmentally friendly film is fabricated through simple self-cross-linking of polyvinyl alcohol (PVA), calcium chloride (CaCl₂), and 3-acrylamidophenylboronic acid (ABA). The film exhibits adaptive moisture sorption-desorption dynamics across wide humidity ranges, enabling efficient cooling. Additionally, PVA-ABA film possesses unique UV-activated fluorescence and room-temperature phosphorescence (RTP) in ambient conditions. Its spectral conversion capability enhances photon utilization in solar cells, increasing short-circuit current density (Jsc) by 2.2%. Under dual functionality, solar cells coated with a PVA-ABA3 film achieve an average temperature reduction of 10.7 °C and a relatively 7.9% improvement in power conversion efficiency (PCE) compared to uncoated cells under simulated sunlight. Outdoor evaluations demonstrate PVA-ABA3 coated solar cells sustain temperature stabilization and achieve a peak enhancement in PCE of 15.4%. This work develops a multifunctional coating that simultaneously addresses thermal management and spectral conversion challenges in PV applications.