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Low-reflection polyethylene terephthalate (PET) films are fabricated with nano-imprinting method. The films are then used to cover polycrystalline silicon solar cells. The morphological and optical properties of films are investigated. The films have periodic cylinder-like nanostructures and relatively low reflectivity in light incident angle ranging from 30${}^{\circ }$ to 60${}^{\circ }$. The nanostructures are with a period of 600 nm and height of 90 nm. Besides, the polycrystalline Si solar cells covered with the films exhibit 12% more power generation than the cells covered with glass. Nano-imprinting method offers a cost-effective approach to fabricate omnidirectional anti-reflection films, which could boost the power generation of Si solar cells. Additionally, the films also have potential applications in different types of solar cells due to its facile fabricating process.

Anti-reflection layers made from sub-wavelength structures or nanostructure arrays have been extensively studied due to the high demand of the solar cell markets and the use of consuming electronics such as plane displays, glasses, prisms, videos, and the monitors of the camera. Conventionally, this anti-reflection layer was fabricated by multilayer films deposition through sputtering, wet-coating or sol-gel. However, these methods have several disadvantages such as process instability, high cost and high temperature procedure.

In the current study, fabrication methods of UV curing and nano-imprinting processes are proposed to produce large-area polymer sheets with sub-wavelength structures (SWS). Porous anodic alumina (PAA) mold of nano-holes was used to fabricate SWS on a PET sheet with UV photoresists of refractive index of 1.53 by roll-to-roll processing. The reflectance of SWS on PET decreases from 9.39 to 4.25% at the wavelength of 550 nm. The contact angle changes from 78.1° to 103.2°. The porous anodic alumina mold was also used to imprint a PMMA film and SWS were obtained by hot embossing at different temperatures. The reflectance changes from 4.25 to 2.16% at the wavelength of 550 nm after nano-imprinting. A successful low cost approach to produce large-area polymer sheets with SWS is obtained by both UV curing and nano-imprinting processes.