Hou Gaoyuan, Liu Yu, Zhang Dejian, Li Guanhui, Xie Hong, Fang Zhiqiang
State Key Laboratory of Pulp and Paper Engineering, South China University of Technology, Guangzhou 510640, China.
South China Institute of Collaborative Innovation, South China University of Technology, Dongguan 523808, China.
ACS Appl Mater Interfaces. 2020 Jul 15;12(28):31998-32005. doi: 10.1021/acsami.0c08586. Epub 2020 Jun 29.
A highly transparent cellulose film with a high built-in haze is emerging as a green photonic material for optoelectronics. Unfortunately, attaining its theoretical haze still remains a challenge. Here, we demonstrate an all-cellulose composite film with a 90.1% transmittance and a maximal transmission haze of 95.2% close to the theoretical limit (∼100%), in which the entangled network of softwood cellulose fibers works as strong light scattering sources and regenerated cellulose (RC) with undissolved fibril bundles functions as a matrix to simultaneously improve the optical transparency and transmission haze. The underlying mechanism for the ultrahigh haze is attributed to microsized irregularities in the refractive index, arising primarily from the crystalline structure of softwood fibers, undissolved nanofibril bundles in RC, and a small number of internal cavities. Moreover, the resulting composite film presents a folding resistance of over 3500 times and good water resistance, and its application in a perovskite solar cell as an advanced light management layer is demonstrated. This work sheds light on the design of a highly transparent cellulose film with a haze approaching the theoretical limit for optoelectronics and brings us a step further toward its industrial production.
一种具有高内禀雾度的高透明纤维素薄膜正作为一种用于光电子学的绿色光子材料崭露头角。不幸的是，达到其理论雾度仍然是一项挑战。在此，我们展示了一种全纤维素复合薄膜，其透光率为90.1%，最大透过雾度为95.2%，接近理论极限（约100%），其中软木纤维素纤维的缠结网络充当强光散射源，而含有未溶解原纤束的再生纤维素（RC）充当基质，以同时提高光学透明度和透过雾度。超高雾度的潜在机制归因于折射率中的微米级不规则性，这主要源于软木纤维的晶体结构、RC中未溶解的纳米原纤束以及少量内部空洞。此外，所得复合薄膜具有超过3500次的抗折叠性和良好的耐水性，并展示了其作为先进光管理层在钙钛矿太阳能电池中的应用。这项工作为设计雾度接近光电子学理论极限的高透明纤维素薄膜提供了思路，并使我们朝着其工业化生产又迈进了一步。
