Double-Network Luminescent Films Constructed Using Sulfur Quantum Dots and Lanthanide Complexes
Wenyu Zhang, Haiduo Liang, Xueying Qin, Jiamei Yuan, Xi Wang, Zhenguang Wang, Ying Wang, Jinchao Zhang, Daqing Yang
Abstract
Although UV light-switchable luminescent films are of importance for application in soft optical devices and anticounterfeiting labels, there are still challenges in developing such films integrated with outstanding luminescent property, high self-healing efficiency, and simultaneously excellent mechanical strength. Herein, double-network (DN) luminescent films are designed and constructed via an intermolecular hydrogen bond crosslinking strategy of poly(ethylene glycol) (PEG) in sulfur quantum dots (S-QDs) and polyurethane (PU), where S-QDs (“stone” one) play dual roles of acting both as a soft segment to crosslink another segment PU (“bird” one) and also as the origin of a luminescence center (“bird” two) in films. In addition, lanthanide(III) complexes (LnCs, Ln═Eu 3+, Tb 3+ ) are employed as another emission source to embed in the films and switch the emission colors of DN films from the multicolor (red–yellow–green) of LnCs to the blue color of S-QDs by changing the ultraviolet excitation wavelength from 254 to 365 nm. It is worth noting that the crosslinking network strategy can effectively prevent S-QDs and LnCs from aggregating or leaking and enable both luminescence centers to homogeneously distribute, resulting in luminescent DN films possessing extraordinary UV light-switchable luminescence, improved mechanical property, and excellent self-healing ability. This work presents a viable method for the design and fabrication of luminescent films with multifunctional applications in flexible robotics, wearable devices, and dual-luminescent anticounterfeiting materials.