Transparent wood composite, systems and method of fabrication

Abstract

Highly transparent (up to 92% light transmittance) wood composites have been developed. The process of fabricating the transparent wood composites includes lignin removal followed by index-matching polymer infiltration resulted in fabrication of the transparent wood composites with preserved naturally aligned nanoscale fibers. The thickness of the transparent wood composite can be tailored by controlling the thickness of the initial wood substrate. The optical transmittance can be tailored by selecting infiltrating polymers with different refractive indices. The transparent wood composites have a range of applications in biodegradable electronics, optoelectronics, as well as structural and energy efficient building materials. By coating the transparent wood composite layer on the surface of GaAs thin film solar cell, an 18% enhancement in the overall energy conversion efficiency has been attained.

Description

REFERENCE TO RELATED APPLICATION(S)[0001]This Utility Patent Application is based on the Provisional Patent Application No. 62 / 291,151 filed 4 Feb. 2016.STATEMENT REGARDING FEDERAL SPONSORED RESEARCH OR DEVELOPMENT[0002]This invention was made with government support under FA95501310143 awarded by AFOSR. The government has certain rights in the invention.FIELD OF THE INVENTION[0003]The present invention is directed to light transmitting systems, and in particular to wood-based light transmitting systems.[0004]Even more in particular, the present invention is directed to anisotropic transparent wood mesoporous composites having unique optical properties in a broad wavelength range between 400 nm and 1100 nm which can be utilizable for a wide range of optoelectronic and photonic systems, where light management is crucial for enhanced operation efficiency. The systems provide for high mechanical strength and ductility and may be used as energy efficient building materials for guided su...

AI Technical Summary

Benefits of technology

The present invention provides a cost-effective way to make a transparent wood composite that has excellent optical and mechanical properties. This material can be used as a light management material in optoelectronics and energy conversion devices, as well as a building material to efficiently harvest sunlight for indoor lighting. The transparent wood composite can be attached to buildings to improve thermal insulation and provide better light harvesting during the day.

Problems solved by technology

First, natural wood has microsized channels that scatter light in the visible range.

Second, lignin infiltrating wood (up to 30% by mass) absorbs visible light and leads to the opaque appearance of most woods.

However, extracting CNF from wood is an energy and time consuming process.

However, plastic substrates have intrinsic problems such as poor thermal stability, difficulty in being functionalized, and adding waste to landfills.

(1) Glass often creates shadowing effects and discomforting glare. To create efficient, uniform, and consistent indoor lighting inside the building, the light harvesting window needs to yield effective directional scattering including a high transparency over visible range and a large scattering effect in the forward direction. Current strategies used to realize directional scattering often involve complex nanostructures based on Mie scattering or other resonant scattering effects where the size of the nanostructures must be finely tuned. Consequently, such techniques show limited capability for large-scale commercial applications.

(2) Due to the intrinsic high thermal conductivity of glass, one-third of the energy used to heat or cool the building is lost through inefficient glass windows.

(3) Glass is highly brittle and shatters upon sudden impact, which can lead to safety issues.

However, natural wood is not transparent due to light absorbing lignin and microsized scattering cell lumens.

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