Low-cost, universal light-harvesting coating layer for thin film solar cells by employing micro-prism films

Abstract

Reduction of optical loss in thin-film solar cells, such as polymer solar cells and perovskite solar cells, is a key issue to promote device performance. A number of optical strategies have been investigated to enhance absorption. Among them, the light management layer provides an effective approach. This work designed and fabricated a micro-prism film with a simple technology. It significantly improved the light absorption of the solar cells after coating on the device incident windows. A specific optical model was built by combining ray optics and wave optics to explore the light trapping properties of the micro-prism films. Theoretically, the micro-prism film presented great anti-reflection ability. Its light trapping efficiency depended on the thickness periodically. However, within a wide thickness range in each period, the absorption enhancement remained at the maximum, which lowered the difficulties of thickness control in fabrication. Experimentally, coated with a micro-prism film, the JSC value of the polymer solar cells increases by 13.8%, leading to the power conversion efficiency (PCE) enhancing by 12.1%. On the other hand, perovskite solar cells with a thin active layer were prepared. JSC increased by 10.1% and PCE was enhanced by 6.0%, which were close to those of the device with a typical thick active layer. This also provided a physical way to reduce the heavy metal lead and lower environment pollution risk.