A Solar‐Blind Photodetector Based on MXene/ β ‐Ga 2 O 3 Heterojunction With Superlinear Photoresponse and Synaptic Plasticity

ABSTRACT The demand for wide‐dynamic‐range photodetectors is pressing, yet conventional devices are restricted to fixed‐mode operation, where a single transport mechanism fundamentally limits the performance ceiling of individual photodetectors. Here, we demonstrate a photodetector based on an MXene/ β ‐Ga 2 O 3 van der Waals Schottky junction, whose operational characteristics are governed by the incident light intensity. This heterostructure enables efficient photocarrier separation and interfacial barrier modulation, allowing the device to exhibit distinct working behaviors under different illumination conditions at zero bias. Under strong deep‐ultraviolet irradiation, the device delivers a superlinear photoresponse with a power‐law exponent of 1.47, enabling high‐sensitivity detection of strong signals. By contrast, in the weak‐light regime, the device manifests typical synaptic plasticity features, including pronounced excitatory postsynaptic current, a paired‐pulse facilitation index of up to 200%, and a dynamic transition from short‐term plasticity to long‐term plasticity. This work provides a general pathway for constructing light‐triggered multifunctional optoelectronic devices via interfacial carrier dynamics control, thereby laying a foundation for the advancement of photodetection systems.