Wavelength-Selective Coexistence of Interfacial Photogating and Bolometric Effects Enables Polarity-Switchable Tri-Mode Optoelectronic Behaviors in HfS2 Phototransistor

Abstract

Conventional neuromorphic vision systems suffer from architectural fragmentation, wherein sensing, memory, and processing are distributed across discrete modules, causing high latency, energy waste, and poor dynamic adaptability. Here, we present a wavelength-driven trimodal field-effect phototransistor (TriM-FEP) based on layered HfS₂, which offers a new solution to this challenge. This single device integrates polarity-switchable photoresponses and synaptic dynamics without external bias or complex circuitry. By simply tuning the incident wavelength, the TriM-FEP delivers three distinct, dynamically switchable photoresponses: a synaptic-like photoresponse under solar-blind ultraviolet, fast negative photocurrent in the visible, and fast positive photocurrent in the near-infrared. Notably, this unique polarity reversal and speed variation are dominated by the photogating effect and the bolometric effect at different wavelengths, respectively. Beyond fundamental physics, the TriM-FEP enables real-time multichannel encrypted optical communication and in-sensor image preprocessing, eliminating the need for separate computing units. This work transcends the limitations of multicomponent cooperation, establishing a compact, energy-efficient platform that unifies sensing, memory, and processing at the device level.