Kaschuk Joice Jaqueline, Al Haj Yazan, Valdez Garcia Joaquin, Kamppinen Aleksi, Rojas Orlando J, Abitbol Tiffany, Miettunen Kati, Vapaavuori Jaana
Department of Bioproducts and Biosystems, School of Chemical Engineering, Aalto University, FI-00076, Aalto, Espoo, Finland; Department of Chemical and Biological Engineering, 2360 East Mall, The University of British Columbia, V6T 1Z3 Vancouver, BC, Canada.
Department of Chemistry and Materials Science, School of Chemical Engineering, Aalto University, FI-00076 Aalto, Finland.
Carbohydr Polym. 2024 May 15;332:121877. doi: 10.1016/j.carbpol.2024.121877. Epub 2024 Feb 2.
This work aims to understand how nanocellulose (NC) processing can modify the key characteristics of NC films to align with the main requirements for high-performance optoelectronics. The performance of these devices relies heavily on the light transmittance of the substrate, which serves as a mechanical support and optimizes light interactions with the photoactive component. Critical variables that determine the optical and mechanical properties of the films include the morphology of cellulose nanofibrils (CNF), as well as the concentration and turbidity of the respective aqueous suspensions. This study demonstrates that achieving high transparency was possible by reducing the grammage and adjusting the drying temperature through hot pressing. Furthermore, the use of modified CNF, specifically carboxylated CNF, resulted in more transparent films due to a higher nanosized fraction and lower turbidity. The mechanical properties of the films depended on their structure, homogeneity (spatial uniformity of local grammage), and electrokinetic factors, such as the presence of electrostatic charges on CNF. Additionally, we investigated the angle-dependent transmittance of the CNF films, since solar devices usually operate under indirect light. This work demonstrates the importance of a systematic approach to the optimization of cellulose films, providing valuable insight into the optoelectronic field.
这项工作旨在了解纳米纤维素（NC）加工如何改变NC薄膜的关键特性，使其符合高性能光电子学的主要要求。这些器件的性能在很大程度上依赖于基板的透光率，基板起到机械支撑作用，并优化与光活性组件的光相互作用。决定薄膜光学和机械性能的关键变量包括纤维素纳米原纤维（CNF）的形态，以及各自水悬浮液的浓度和浊度。本研究表明，通过降低克重和通过热压调整干燥温度，可以实现高透明度。此外，使用改性CNF，特别是羧化CNF，由于纳米级部分比例更高和浊度更低，可得到更透明的薄膜。薄膜的机械性能取决于其结构、均匀性（局部克重的空间均匀性）以及电动因素，例如CNF上静电荷的存在。此外，由于太阳能器件通常在间接光照下运行，我们研究了CNF薄膜的角度相关透光率。这项工作证明了采用系统方法优化纤维素薄膜的重要性，为光电子领域提供了有价值的见解。
