Scalable, anisotropic transparent paper directly from wood for light management in solar cells

The growing demand for flexible electronics and solar energy conversion devices has fueled a search for high-quality paper-based materials with excellent mechanical flexibility and optical properties such as high transparency and haze. Despite the tremendous efforts have been dedicated to developing paper-based materials with high transparency or high haze, challenges still remain in achieving both due to the general exclusivity between them. Here, for the first time, we develop a novel anisotropic paper material possessing high mechanical flexibility and fantastic optical properties with both high transmittance (~90%) and high haze (~90%) simultaneously via a simple yet effective “top-down” approach by directly shear pressing the delignified wood material. The anisotropic transparent paper demonstrates a high efficiency as a light management coating layer for GaAs solar cell with a significant efficiency enhancement of 14% due to its excellent light management capability with both high transparency and high haze. The presented “top-down” approach is facile, scalable, cost-effective and “green”, representing a promising direction for developing flexible electronics, solar energy conversion devices and beyond.