Temperature-Sensitive Electroluminescent Devices Based on a High-Adhesive Self-Healing Hydrogel

Abstract With the rapid advancement of flexible electronics, there is a growing demand for optoelectronic devices that combine softness, stretchability, and multifunctional integration. However, conventional flexible alternating current electroluminescent (ACEL) devices exhibit notable limitations in interfacial adhesion, mechanical robustness, and environmental responsiveness, which hinder their broader application in wearable electronics, human−machine interfaces, and intelligent sensing systems. In this study, a temperature-responsive, highly adhesive, and self-healing hydrogel electrode was developed and integrated into an ACEL device. By incorporating 2-(dimethylamino)ethyl methacrylate (DMAEMA), a multifunctional hydrogel electrode was developed to integrate temperature-responsive optical/electrical modulation, reversible self-healing, stretchability, and adhesion. At the optimized DMAEMA content of 6.67 mmol, the hydrogel achieved an adhesion strength of 0.044 MPa on porcine skin and a tensile strength of 18.7 kPa. The hydrogel also exhibited reversible optical modulation, with the transmittance changing from approximately 80% at 30 °C to approximately 50% at 60 °C during repeated heating−cooling cycles. When integrated into the ACEL device, the hydrogel electrode regulated the device luminance through coupled temperature-dependent resistance and transmittance changes. In the physiologically relevant temperature range of 34−42 °C, the luminance decreased from 6.5 to 3.8 cd m−2, corresponding to a relative temperature sensitivity of −5.7 to −7.5% °C−1. Electrical−optical decoupling analysis indicated that the resistance-induced electrical modulation dominated the luminance attenuation, contributing more than 70% of the total response in the 40−60 °C range. The device maintained stable electroluminescence under tensile strains up to 500% and operated continuously for 12 h with a surface temperature of approximately 30 ± 3 °C. This work provides a hydrogel-electrode-based strategy for integrating thermal sensing, luminance modulation, self-healing, and mechanical deformability in flexible ACEL devices.