A transparent, flame-retardant, and UV-resistant polycarbonate panel with high down-conversion efficiency opens up possibilities for lightweight solar cell encapsulation panels

Solar power, as a clean and renewable energy source, holds tremendous potential for future energy systems. This study presents lightweight, flame-retardant, and durable polycarbonate (PC) encapsulation panels incorporating a fluorescent agent to substitute the glass covers in photovoltaic (PV) modules. A novel fluorescent derivative (TPA-BPOD), synthesized from triphenylamine and phenyl phosphonic dichloride, was doped into PC at a concentration of 0.5 wt%. The resulting PC panel (0.7 mm thickness) exhibited visible-light transmittance comparable to that of pure PC while effectively converting ultraviolet (UV) light to visible wavelengths. When applied to silicon solar cells as a front encapsulant, the PC+0.5%TPA-BPOD panel increased the power conversion efficiency (PCE) by 3.5%. Furthermore, the PC panel (1.6 mm thickness) demonstrated superior flame retardancy, achieving a UL-94 V-0 rating and a limiting oxygen index (LOI) of 28.8%, along with a significantly suppressed release of toxic gases during combustion. After 360 h of accelerated UV aging (500 W, 60 °C), the PC+0.5%TPA-BPOD panel retained better mechanical properties than the undoped control, highlighting its improved durability. By enabling lightweight, safe, and efficiency-boosting PV encapsulation, this strategy supports the development of next-generation solar technologies, particularly for building-integrated or vehicle-integrated photovoltaics and flexible solar applications.