Preparation of UV Curable Optical Adhesive NOA81 Bionic Lotus Leaf Structure Films by Nanoimprint Technique and the Applications on Silicon Solar Cells

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Front surface texturing is a common method used to improve the optical performance of photovoltaic devices. However, traditional texturing techniques may be challenging in some cases, such as when dealing with ultra-thin substrates. Textured polymer films on such devices would be an alternative approach. This paper reports a study of NOA81 thin films with a bionic lotus leaf surface structure on monocrystalline silicon solar cells. Inspired by the surface structure of natural lotus leaves, we successfully prepared a bionic lotus leaf microstructure film on the surface of solar cells based on NOA81 using polydimethylsiloxane (PDMS) polymer and nanoimprinting methods. Scanning electron microscopy (SEM) images showed that the surface structure of the NOA81 thin film was the same as that of natural lotus leaves. A UV-Vis spectrophotometer with an integrating sphere was used to measure the reflectance of the textured NOA81 film on the silicon wafer. Results showed that the textured NOA81 film could effectively reduce the reflectance of the silicon wafer surface. We also used finite-difference time-domain (FDTD) simulation to verify this conclusion further. Finally, the I-V characteristics of the prepared solar cells with the textured NOA81 film were investigated, and the highest photovoltaic efficiency was measured to be about 16.07%, effectively improving the photoelectric conversion efficiency. In addition, the film with textured NOA81 can be used as a protective film for monocrystalline silicon solar cells.