Interactive deformable electroluminescent devices enabled by an adaptable hydrogel system with optical/photothermal/mechanical tunability.

Deformable electroluminescent devices (DELDs) with mechanical adaptability are promising for new applications in smart soft electronics. However, current DELDs still present some limitations, including having stimuli-insensitive electroluminescence (EL), untunable mechanical properties, and a lack of versatile stimuli response properties. Herein, a facile approach for fabricating in situ interactive and multi-stimuli responsive DELDs with optical/photothermal/mechanical tunability was proposed. A polyvinyl alcohol (PVA)/polydopamine (PDA)/graphene oxide (GO) adaptable hydrogel exhibiting optical/photothermal/mechanical tunability was used as the top ionic conductor (TIC). The TIC can transform from a viscoelastic state to an elastic state via a special freezing-salting out-rehydration (FSR) process. Meanwhile, it endows the DELDs with a photothermal response and thickness-dependent light shielding properties, allowing them to dynamically demonstrate "on" or "off" or "gradually change" EL response to various mechanical/photothermal stimuli. Thereafter, the DELDs with a viscoelastic TIC can be utilized as pressure-responsive EL devices and laser-engravable EL devices. The DELDs with an elastic TIC can withstand both linear and out-of-plane deformation, enabling the designs of various interactive EL devices/sensors to monitor linear sliders, human finger bending, and pneumatically controllable bulging. This work offers new opportunities for developing next-generation EL-responsive devices with widespread application based on adaptable hydrogel systems.