Green Fabrication of All-Nanocellulose-Based Flexible Electroluminescent Devices with Biodegradability, Recyclability, and Extreme Environment Tolerance
Ya Lu, Haoyu Sun, Fang Deng, Yiying Yue, Shuijian He, Shaohua Jiang, Qinglin Wu, Huining Xiao, Jingquan Han
Abstract
Flexible electroluminescent (EL) devices have become an important part of lighting and display. However, fabricating a flexible EL device with biodegradability, recyclability, and extreme environment tolerance through a facile and green method still remains challenging to date. Herein, an all-nanocellulose-based flexible EL device with recyclable phosphors is developed by using a sandwich-structured assembly strategy. Biomass-derived cellulose nanocrystals with II crystalline allomorphs (CNCs II) with high transmittance are utilized as a film-forming agent, a dispersant, and an antioxidant for transparent electrodes. Biomass-derived cellulose nanofibers with a high aspect ratio are introduced into the luminescent layer to improve the mechanical stability of the devices. The CNC II-silver nanowire electrodes with high transmittance (81.7%) and low sheet resistance (4.4 Ω sq –1 ) demonstrate conductive stability, damage resistance, and inoxidizability. The assembled EL devices with high luminance (135.7 cd m –2 at 400 V and 20 kHz), tensile strength (16.6 MPa), and mechanical cyclic stability can work properly over a wide temperature range (−20 to 60 °C). With the action of cellulase, the entire device can be completely biodegraded within 7 h. The device prepared with recycled phosphors basically maintains the original mechanical and luminescent properties. The patternable all-nanocellulose-based EL devices with biodegradability, recyclability, and extreme environment tolerance manufactured through an environmentally friendly approach offer a favorable option for future green electronics including wearable devices and flexible display screens.