High Performance Stretchable PVA-MoS2 Hydrogel Photodetectors with Electron–Cation Dual Charge Transport

Abstract

Conventional ethylene glycol–borax cross-linked PVA-MoS2 hydrogel photodetectors only rely on isolated MoS2 electronic conduction pathways, which trigger severe nonradiative recombination of photogenerated electron–hole pairs and poor mechanical stretch resistance simultaneously. The lack of mobile ionic channels and unstable MoS2 conductive networks severely limit both photoelectric conversion efficiency and long-term working stability under dynamic deformation. To break through these dual bottlenecks, herein we develop an ion-coordination strategy to construct a synergistic electron–cation dual transport system, where Li+ forms reversible coordination bonds with oxygen-containing groups on the hydrogel matrix to simultaneously build two interconnected charge transport pathways. The cation migration channels offer free-moving Li+ to neutralize photogenerated holes and weaken Coulomb confinement for suppressed carrier recombination, while the coordination anchors MoS2 nanosheets firmly on polymer skeletons to maintain intact electronic percolation networks under stretching. We identify 4 mg mL–1 as the critical threshold concentration to form continuous long-range cation transport channels within the hydrogel network. Benefiting from the dual-channel synergistic effect, the optimized ion-modified hydrogel delivers a 364% elevated photocurrent density of 4.523 μA cm–2 at 0.6 V bias with 120 mW cm–2 illumination compared with unmodified pristine PVA-MoS2. Moreover, the dual-channel hydrogel maintains fully reversible and steady photoresponse under 200% tensile strain over 5000 s continuous illumination cycles. This facile coordination-mediated dual-channel engineering provides a universal strategy to synchronously optimize photoresponse and deformation tolerance, shedding new light on high-performance, long-lifetime stretchable wearable photodetectors.