Anisotropic flexible transparent films from remaining wood microstructures for screen protection and AgNW conductive substrate

Flexible transparent conductive films or substrates prepared from plastics or cellulose are widely used in optoelectronic devices. However, all of these films or substrates are fabricated by complex and expensive methods, which consume much energy and time. In this work, we report for the first time a remarkably facile and effective approach for fabricating flexible transparent films directly from wood. The resulting films exhibit an array of exceptional optical and mechanical properties. The well-aligned cell structures in natural wood are maintained during delignification, leading to anisotropic films with high transparency (≈90% transmittance). These anisotropic films with well-aligned cell structures show mechanical tensile strengths higher than those of the original wood, and can be used as screen protection films for cellphones. Furthermore, ultrathin, highly transparent, and outstandingly conductive films have been prepared from such films and silver nanowires (AgNWs) using the Meyer technique. A conductive film with an optimal area density (341 mg m-2) of AgNWs showed outstanding synergistic properties, with a transmittance of 80% and a sheet resistance of 11 Ω sq-1, equal to the conductivity of ITO. Of importance here is that the low-cost anisotropic transparent wood film shows promising potential for electronics applications in solar cells, flexible displays, and other products.