Novel EPE co-extruded encapsulating films with UV down-conversion power gain effect for highly efficient solar cells

How to maintain or even improve the performance of solar cells under the influence of high temperature, high humidity and intense ultraviolet light has always been a challenging research topic. Here, we propose a novel and effective solution by combining the benefits of EVA (ethylene vinyl acetate), POE (polyolefin) and UV down-conversion (UV-DC) fluorescent nanomaterial (Sr2-xMgSi2O7-x: Eu2+, Dy3+) to construct the first commercially available UV-DC EPE co-extruded encapsulating film with a three-layer composite structure. On the one hand, the UV-DC EPE incorporates the high adhesive strength of EVA and the strong weather resistance of POE. On the other hand, the UV-DC EPE can also convert the UV irradiation, inefficient for power generation and easily cause damage to solar cells, into visible light range with high quantum efficiencies. Therefore, we discover that the UV-DC EPE not only shows higher stability than other encapsulation films under potential-induced degradation (PID), pressure cooker test (PCT), UV and natural sunlight aging tests, but also enhances the power generation efficiencies by 0.3% and 2.3% compared with the UV-transmitting and the UV-filtering EPE films, respectively. The progress in this work breaks the stereotypical definition of encapsulation that only slows down attenuation, but integrates the advantages of power gain effect, high stability, and low cost into the novel encapsulation material and technology, which is expected to be promoted and industrialized in the near future.