Strong, robust cellulose composite film for efficient light management in energy efficient building

• A simple, timesaving strategy was proposed for preparing cellulose-CF. • The cellulose-CF shows high transparency, haze and superior anti-ultraviolet. • The cellulose-CF exhibits strong mechanical strength and high wet strength. • The cellulose-CF shows fire-resistance ability and impact absorption capacity. Energy-saving materials in buildings enable meaningful reduction of indoor energy consumption and are critical to develop a carbon-neutrality society. Accordingly, lighting in modern buildings should be properly managed toward energy-efficient buildings. Here, we developed a broadband light-management cellulose composite film, composed of 75 wt% cellulose bonded by phenol formaldehyde resin, which shows a high transparency (~86%) and haze (~90%) for effective light propagating and scattering, and more importantly, a superior anti-ultraviolet capability (~83% absorptance and ~17% reflectance), thus enabling a soft, uniform, large areal, and safe illumination of the sunlight in buildings toward a comfortable, healthy yet energy-saving environment. In addition, our cellulose composite film features a strong mechanical strength (140 MPa tensile strength) and superior robustness ( e.g., high hydro-stability with a high wet strength of 135 MPa, thermal stability and fire-resistance ability, as well as excellent impact absroption capacity), proving its durability for long-term indoor or outdoor applications. The cellulose composite film is synthesized by a simple and scalable calendaring-like process which can be fully compatible with current paper-making industry. These integrated merits of our cellulose composite film make a promising candidate for energy efficient building applications toward a sustainable society.