As one of the most abundant renewable and biodegradable materials in nature, cellulose is difficult to dissolve in common organic and inorganic liquids. Here, a series of regenerated cellulose films were prepared by using a specific tetra-butylammonium hydroxide TBAH/H 2 O/DMSO ternary solvent system. Especially, the fluorescent cellulose film was obtained successfully via a ring-opening grafting reaction between a modified fluorescein molecule with 3-expoxypropoxy and cellulose. The fluorescent cellulose films exhibited excellent fluorescence stability and pH sensitivity to the aqueous solutions with different degree of acid and alkaline. Moreover, the anisotropic fluorescein cellulose film was obtained for the first time by stretching and further drying the initial fluorescence cellulose hydrogel, and displayed a novel polarized emission. This work provided a simple, low-cost and environment-friendly pathway to fabricate fluorescent cellulose films, showing potential applications in packaging, decoration materials and other functional materials such as anti-counterfeiting paper.
Huanyu Zhang,Tingxiu Yu,Chaoqiang Wang,Ruofei Jia,Azhar Ali Ayaz Pirzado,Di Wu,Xiujuan Zhang,Xiaohong Zhang,Jiansheng Jie
Micro-/nanosized organic–inorganic hybrid perovskite single crystals (SCs) with appropriate thickness and high crystallinity are promising candidates for high-performance electroluminescent (EL) devices. However, their small lateral size poses a great challenge for efficient device construction and performance optimization, causing perovskite SC-based light-emitting diodes (PSC-LEDs) to demonstrate poor EL performance. Here, we develop a facile liquid-insulator bridging (LIB) strategy to fabricate high-luminance PSC-LEDs based on single-crystalline CH3NH3PbBr3 microflakes. By introducing a blade-coated poly(methyl methacrylate) (PMMA) insulating layer to effectively overcome the problems of leakage current and possible short circuits between electrodes, we achieve the reliable fabrication of PSC-LEDs. The LIB method also allows us to systematically boost the device performance through crystal growth regulation and device architecture optimization. Consequently, we realize the best CH3NH3PbBr3 microflake-based PSC-LED with an ultrahigh luminance of 136100 cd m–2 and a half-lifetime of 88.2 min at an initial luminance of ∼1100 cd m–2, which is among the highest for organic–inorganic hybrid perovskite LEDs reported to date. Moreover, we observe the strong polarized edge emission of the microflake-based PSC-LEDs with a high degree of polarization up to 0.69. Our work offers a viable approach for the development of high-performance perovskite SC-based EL devices.
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