Transparent Cellulose Nanofibrils Composites with Two-layer Delignified Rotary-cutting Poplar Veneers (0°-layer and 90°-layer) for Light Acquisition of Solar Cell

Abstract

Our transparent cellulose nanofibrils composites (TCNC) directly from rotary-cutting poplar veneer (RPV) whose lignin can be easily stripped by our treatment. This TCNC is prepared by stripping lignin of original RPV and infiltrating epoxy resin (ER) into delignified RPV. This TCNC with two-layer delignified RPVs whose grains perpendicular (0/90°) to each other, which were solidified on solar cell while infiltrating ER. This TCNC with high transmittance (~90%), high haze (~90%), and equal refractive index fluctuation. Comparing with epoxy resin (ER), this TCNC can enhance open circuit voltage (VOC) from 1.16 to ~1.36 and short circuit density (JSC) from 30 to ~34 for the solar cell, and can enhance test fore from 0.155 kN to ~0.185 kN and displacement from 43.6 mm to ~52.5 mm. Wood is a kind of abundant organic macromolecule resource on the earth. Wood has excellent material properties which including high strength, high toughness, high modulus, low density, low thermal conductivity, biodegradability, sustainability and so on 1-3. The contents of wood mainly include cellulose and hemicellulose (≈70%), lignin (≈30%), and its cellulose and hemicellulose are colourless substance 4,5. New wood functionalization approaches have made it possible to combine load-bearing and functional properties in biobased wood structures 6-12. After stripping lignin or chromogenic groups, a kind of transparent wood composites (TWC) can be prepared by infiltrating the cavity of wood with a polymer 3,4,13-16. The TWC with high transmittance and high haze for light acquisition of solar cell, which have a significant enhancement in solar energy conversion efficiency 17-22. Some researchers have prepared TWC for light management in solar cells 17,18 , and they focused on TWC from radial-cutting veneer for two reasons. First, radial-cutting veneer is easier than rotary-cutting veneer in delignification. Second, radial-cutting veneer has equal refractive index fluctuation, but rotary-cutting veneer hasn't. However, rotary-cutting veneer could obtain far larger breadth from wood trunk to compare with radial-cutting veneer. Farmed poplar is a kind of widely distributed agro-forestry tree species in many nations due to its fast growth rate, short rotation period, multiple uses and high economical value 23-27. Reasonable use of farmed poplar can meet the human demand for TWC, and can avoid the consumption of natural forest resources 27. Poplar has the characteristics of ultra-short fibers, and its rotary-cutting poplar veneer (RPV) is better than radial-cutting poplar veneer (RPV) in mechanical properties 28,29. In our works, the kind of transparent cellulose nanofibrils composites (TCNC) directly from rotary-cutting poplar veneer (RPV) whose lignin can be easily stripped by our treatment. The RPV is from mature trunk of farmed poplar. This TCNC is prepared by stripping lignin of original RPV and infiltrating epoxy resin (ER) into delignified RPV. This TCNC with two-layer delignified RPVs whose grains perpendicular (0/90°) to each other, which w...

Emerging Engineered Wood for Building Applications

“…In these reports, transparent wood was obtained from radial-cut veneer, which is easier to delignify and impregnate and with good optical properties, but rather limited in size. To alleviate this problem, a two-layer transparent wood with channels oriented perpendicular (0/90°) to each other, obtained from rotary-cut veneer, was proposed to increase the performance of a conventional silicon solar cell (Figure C) . Nevertheless, the challenges associated with long-time exposure of transparent wood to intense light sources have not yet been taken into account, which limits the real-world applicability of these systems.…”

“…To alleviate this problem, a two-layer transparent wood with channels oriented perpendicular (0/90°) to each other, obtained from rotary-cut veneer, was proposed to increase the performance of a conventional silicon solar cell (Figure 15C). 156 Nevertheless, the challenges associated with long-time exposure of transparent wood to intense light sources have not yet been taken into account, which limits the real-world applicability of these systems. It is noteworthy that the application of luminescent transparent wood for luminescent solar concentrators (LSCs) has been suggested but not yet demonstrated in practice.…”

Plant‐Based Structures as an Opportunity to Engineer Optical Functions in Next‐Generation Light Management

“…[ 89 ] The layering of wood sections with perpendicular fiber alignment was found to give a material with high transmittance (≈90%), high haze (≈90%), and isotropic in‐plane refractive index. [ 90,91 ]…”

“…[89] The layering of wood sections with perpendicular fiber alignment was found to give a material with high transmittance (≈90%), high haze (≈90%), and isotropic in-plane refractive index. [90,91] Holo-CNF, consisting of CNF with intact hemicellulose, is a good option for transparent materials since hemicellulose helps to stabilize colloidal suspensions and thus provides more homogeneous materials. [92] Holo-CNF has been produced by microfluidization [93] and using a kitchen blender, [94] with Holo-CNF films presenting different transparency and haze values, depending on the processing approach.…”

Designing functional wood materials for novel engineering applications

“…More recently, the Berglund group described the use of transparent wood as substrate for a low temperature (<150 °C)-processed perovskite solar cell (Y. . Zou et al (2020) proposed a two-layer transparent wood, with channels oriented perpendicular (0/90°) to each other, obtained from rotary-cut veneer to increase the performance of a conventional silicon solar cell. Finally, the application of luminescent transparent wood for luminescent solar concentrators (LSCs) has been suggested, but not yet demonstrated in practice (Li et al 2017b).…”