In additional to the anisotropic behavior of the optical
properties, we also investigated the total transmittance and
optical transmittance haze of the transparent wood composite
(Figure 4 k,l). Integrated sphere was used to measure the optical
transmittance and transmittance haze. Nature L- and R-wood
shows almost negligible transmittance due to the strong lignin
absorption. After lignin extraction and polymer infi ltration,
both types of transparent wood composites show dramatically
high transmittance as illustrated in Figure 4 k. The R-wood
transmittance is up to 90%, higher than L-wood, which may be
due to better fi lling of polymer because of the small depth for
the lumina. Interestingly, both samples exhibit large haze covering
the entire visible wavelength ranging from 400 to 800 nm,
while R-wood shows a generally higher value than that of
L-wood (Figure 4 l). For the transparent wood composite where
the interface between the microsized cellulose and the polymer
has a roughness larger than the wavelength of the incoming
light, the scattering intensity is almost independent of the wavelength.
This broad range light management is often referred to
as Mie scattering. [ 20 ] The high optical haze as exhibited by both
types of wood can be potentially used for a wide range of optoelectronics
applications where advanced light management is
needed to improve the light coupling and extraction effi ciency,
such as solar cells and displays