Tunable Bi‐directional Photoresponse in Hybrid PtSe_2−x Thin Films Based on Precisely Controllable Selenization Engineering

Abstract

Bi‐directional photodetection with positive and negative photoconductance (PPC/NPC) plays a critical role in building next‐generation artificial neuromorphic systems, visual information processing and optoelectronic logic gates of the future. However, the typical device configuration based on heterostructures with strict working principles restricts the diversity of material selection. In this work, a novel strategy is proposed to fabricate bi‐directional photoresponse devices based on PtSe2−x films with precisely controllable selenization engineering. It is found that the PtSe2−x films are composed of Pt and PtSe2 components. The direction of the photocurrent can be reversibly modulated in a broadband range by tuning the ratio of PtSe2 in the film, which is ascribed to the synergistic mechanism of bolometric effect of Pt and photoconductive effect of PtSe2. The polarity switching wavelength from NPC to PPC can be further modulated through tuning the components of the film for specific demand. The tunable bi‐directional photoresponse enables the device to mimic the fundamental functions of artificial synapses all optically, such as aversion learning capability and logical functions, with high paired pulse facilitation index. This work potentially opens an opportunity for the development of advanced artificial neuromorphic systems and optoelectronic logic gates.

Reconfigurable Neuromorphic Computing: Materials, Devices, and Integration

“…Several all-optically modulated neuromorphic devices with maneuverable synaptic or logic functionalities were proposed based on materials, such as ZnO/PbS heterostructure, [160] perovskite/ZnO heterostructure, [161] and PtSe 2−x films. [162] The utilization of defects is regarded as a promising strategy to explore bidirectional optical modulation. Ahmed et al presented a fully light-controlled versatile synaptic device with defective BP.…”

Boolean Logic Computing Based on Neuromorphic Transistor

“…Liang et al fabricate a bidirectional photo-responsive de-vice through PtSe 2-x films synthesized by controllable selenization engineering (Figure 9e). [124] Due to the coupling between the positive photoconductivity effect of PtSe 2 and the negative radiative thermal effect of Pt, the photocurrent suppression and enhancement of the device are realized with light irradiation at 405 nm and 980 nm, respectively (i.e., IPSC and EPSC). Yang et al construct a bidirectional photo-responsive device based on Bi 2 O 2 Se/graphene mixed structure (Figure 9f).…”

“…e) Schematic diagram of bidirectional photo-responsive neuromorphic transistors based on PtSe 2 and Pt. Reproduced with permission [124]. Copyright 2022, Wiley.…”

All‐Optical‐Controlled Excitatory and Inhibitory Synaptic Signaling through Bipolar Photoresponse of an Oxide‐Based Phototransistor

“…As a result, all-optical synaptic devices show a potential way to overcome these drawbacks, which can be triggered by light with various wavelengths. [16][17][18][19][20] The integration of sensing and processing units into a single all-optical-controlled device can significantly reduce data transfer energy and simplify the system structure. [21] They have the great potential to realize next-generation photonic computing systems with high-density integration, reduced power consumption, high bandwidth, and low crosstalk for nonstructured visual data and real-time information processing.…”