Ultrasensitive\nFlexible Solar-Blind Photodetectors\nBased on Graphene/Amorphous Ga<sub>2</sub>O<sub>3</sub> van der Waals\nHeterojunctions

Flexible photodetectors (PDs) have\nbecome the latest research interest\nowing to their potential applications in future implantable sensors\nand foldable/wearable optoelectronics. Ga₂O₃, an emerging ultrawide band gap semiconductor, is considered as\nthe native photosensitive material for solar-blind PDs. The reported\nfabrication temperature of Ga₂O₃ films is usually\nabove 600 °C, which hinders its practical application for flexible\ndevices. In this work, flexible PDs based on graphene/amorphous Ga₂O₃ van der Waals heterojunctions are fabricated,\nwhich demonstrate promising photoresponse to solar-blind ultraviolet\nlight. The device yields a high photo-to-dark current ratio (∼10⁵) and large responsivity (22.75 A/W) under 254 nm light illumination,\nwhich could be ascribed to the efficient photogenerated electron–hole\npair separation by the strong built-in field. Moreover, flexible PDs\nalso show long-term environmental stability and outstanding mechanical\nflexibility without any encapsulation. Our work provides a new potential\ncandidate for realizing cost-effective high-performance flexible optoelectronic\napplications.