Nanopatterned silk fibroin films with high transparency and high haze for optical applications

Simultaneous high transparency and high haze are necessary for high-efficiency optical, photonic, and optoelectronic applications. However, a typical highly transparent film lacks high optical haze or vice versa. Here, we report a silk fibroin-based optical film that exhibits both ultrahigh optical transparency (>93%) and ultrahigh optical transmission haze (>65%). Also, in combination with the soft lithography method, different nanostructured silk fibroin films are presented and their optical properties are characterized as well. To demonstrate its exceptional performance in both high transmission and high optical haze, we combine the silk fibroin with the silicon photodiode and show that the efficiency can be increased by 6.96% with the silk fibroin film without patterns and 14.9% with the nanopatterned silk fibroin film. Silk provides excellent mechanical, optical, and electrical properties, and the reported high-performance silk fibroin can enable the development of next-generation biocompatible eco-friendly flexible electronic and optical devices.