Transparent and haze wood composites for highly efficient broadband light management in solar cells

Highly efficient broadband light management to enhance the light trapping inside active layer is critical for many energy conversion devices such as thin film solar cells and photoelectrochemical cells. In this work, we demonstrate highly transparent, mesoporous wood composite via fast extraction of lignin along naturally formed low tortuosity channels followed by fast filling of polymers. The transparent wood displays a high optical transmittance and at the same time a high haze in a broad wavelength range between 400 nm and 1100 nm. With such unique optical properties, the transparent wood composite with cellulose nanofibers can be utilized for a range of optoelectronics, especially for solar cells and wide-angle lighting where light management is crucial to enhance device operation efficiency. We demonstrate that the newly developed transparent wood composite can function as a broad range light management layer and substantially improve the overall energy conversion efficiency by as much as 18% when simply coated with a GaAs thin film solar cell. Our research on wood based light management material provides an attractive platform for future development embracing green, disposable optoelectronic devices with efficient light management.