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.

中文翻译：

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具有生物降解性、可回收性和极端环境耐受性的全纳米纤维素基柔性电致发光器件的绿色制造


柔性电致发光（EL）器件已成为照明和显示的重要组成部分。然而，迄今为止，通过简便、绿色的方法制造具有生物可降解性、可回收性和极端环境耐受性的柔性电致发光器件仍然具有挑战性。在此，通过使用三明治结构组装策略开发了一种具有可回收荧光粉的全纳米纤维素基柔性电致发光器件。生物质衍生的具有高透光率的 II 型结晶同质异形体 (CNCs II) 的纤维素纳米晶体被用作透明电极的成膜剂、分散剂和抗氧化剂。将具有高长径比的生物质衍生的纤维素纳米纤维引入发光层中，以提高器件的机械稳定性。 CNC II-银纳米线电极具有高透光率（81.7%）和低方块电阻（4.4 Ω sq ^–1 ），表现出导电稳定性、抗损伤性和抗氧化性。组装的EL器件具有高亮度（在400 V和20 kHz下为135.7 cd m ^–2 ）、拉伸强度（16.6 MPa）和机械循环稳定性，可以在较宽的温度范围（−20至60 ℃）。在纤维素酶的作用下，整个装置可在7小时内完全生物降解。采用回收荧光粉制备的器件基本保持了原有的机械性能和发光性能。通过环保方法制造的可图案化全纳米纤维素基EL器件具有生物可降解性、可回收性和极端环境耐受性，为未来的绿色电子产品（包括可穿戴设备和柔性显示屏）提供了有利的选择。