Scalable, highly transparent paper with microsized fiber

Patent metadata

Field	Value
Publication number	US-2016010279-A1
Application number	US-201414563387-A
Country	US
Kind code	A1
Filing date	Dec 8, 2014
Priority date	Dec 6, 2013
Publication date	Jan 14, 2016
Grant date	—

Abstract

Solar cell substrates require high optical transparency, but also prefer high optical haze to increase the light scattering and consequently the absorption in the active materials. Unfortunately there is a tradeoff between these optical properties, which is exemplified by common transparent paper substrates exhibiting a transparency of about 90% yet a low optical haze (<20%). In this work we introduce a novel transparent paper made of wood fibers that display both ultra-high optical transparency (˜96%) and ultra-high haze (˜60%), thus delivering an optimal substrate design for solar cell devices. Compared to previously demonstrated nanopaper composed of wood-based cellulose nanofibers, our novel transparent paper has better dual performance in transmittance and haze, but also is fabricated at a much lower cost. This high-performance, low-cost transparent paper is a potentially revolutionary material that may influence a new generation of environmentally friendly printed electronics.

First claim

What is claimed is:

1 . A transparent paper comprising:
an optical transparency of at least 96%; and an optical haze of at least 60%.

2 . The transparent paper of claim 1 further comprising;
a cell wall;
a plurality of wood fibers in the cell wall,
wherein the plurality of wood fibers comprise a primary layer and a secondary layer, the primary layer having a thickness of 0.1-0.2 μm and the secondary layer having a thickness of about 1.0-5.5 μm.

3 . The transparent paper of claim 2 wherein the wood fibers comprise a plurality of microfibrils, the plurality of microfibrils being randomly oriented in the primary layer and helically wound in a fiber axis of the secondary layer.

4 . The transparent paper of claim 2 wherein the wood fibers have a diameter of 5 nm to 20 nm, a tensile strength of about 105 MPa, and a toughness of about 1.88 J/M 3 .

5 . A method of making transparent paper comprising the steps of:
(a) treating bleached sulfate softwood pulp with a TEMPO-Oxidized system comprising;
(i) dispersing 5 g of wood fibers into 1% pulp with deionized water to make wood pulp;
(ii) adding TEMPO and sodium bromide (NaBr) separately into the wood pulp;
(iii) stifling the mixture continuously to form a uniform suspension;
(iv) titrating the uniform suspension with sodium hypochlorite (NaClo);
(b) filtrating the uniform suspension; and (c) fabricating a transparent paper from the filtrated uniform suspension.

6 . The method of making transparent paper of claim 1 wherein the bleached sulfate softwood pulp is extracted from the southern yellow pine without beating or refining.

7 . A solar cell application comprising:
a laminated transparent paper, the laminated transparent paper comprising an optical transparency of at least 96% and an optical haze of at least 60%.

8 . The solar cell application of claim 1 , wherein the laminated transparent paper further comprises:
a cell wall; a plurality of wood fibers in the cell wall, wherein the plurality of wood fibers comprise a primary layer and a secondary layer, the primary layer having a thickness of 0.1-0.2 μm and the secondary layer having a thickness of about 1.0-5.5 μm.

9 . The solar cell application of claim 8 , wherein the wood fibers comprise a plurality of microfibrils, the plurality of microfibrils being randomly oriented in the primary layer and helically wound in a fiber axis of the secondary layer.

Assignees

• Univ Maryland

Inventors

• Hu Liangbing
• Fang Zhiqiang
• Zhu Hongli

Classifications

• D21H17/66

  Salts, e.g. alums · CPC title

• D21H17/07 Primary

  Nitrogen-containing compounds · CPC title

• H10F77/315

  the coatings being antireflective or having enhancing optical properties · CPC title

• H10F19/80

  Encapsulations or containers for integrated devices, or assemblies of multiple devices, having photovoltaic cells · CPC title

• H10F10/00

  Individual photovoltaic cells, e.g. solar cells (electrolytic light-sensitive devices, e.g. dye-sensitised solar cells, H01G9/20) · CPC title