Broadband Polarization-Gated Bipolar Photoresponse in a Twisted Anisotropic Heterojunction for a Multifunctional All-Optical Logic Gate and Miniaturized Spectrometer.

Zhang, Xinlei; Liu, Wentao; Li, Ruizhi; Lin, Rui; Zhou, Tao; Zhang, Yuwei; Yang, Fang; Wang, Wenhui et al. · Nano Lett · 2026

basic_science · Level V

Where this comes from

Abstract

A bipolar photoresponse is essential for all-optical logic and neuromorphic computing yet remains challenging to achieve with precise tunability, fast response, and broadband operation within a single device. Here, we report a polarization-gated reversible bipolar photoresponse enabled by a twisted black phosphorus (BP)/Bi<sub>2</sub>O<sub>2</sub>Se/BP van der Waals heterostructure. The bipolar photoresponse arises from the combined effect of dual oppositely oriented built-in electric fields in back-to-back BP/Bi<sub>2</sub>O<sub>2</sub>Se heterojunctions and anisotropic absorption of BP. This twist-configured heterostructure produces a broadband bipolar photovoltaic response spanning 1000-3500 nm with excellent stability. Benefiting from the photovoltaic effect, the device achieves a fast response time of 4.3 μs and low noise equivalent power of 47 pW Hz<sup>-1/2</sup>. As a proof of concept, the bipolar photodetector enables six all-optical logic operations and a miniaturized spectrometer (1000-1600 nm) via reconstruction algorithms. This work presents an electronic-free architecture for all-optical logic and neuromorphic computing within polarization-gated bipolar devices.