A MoS₂/PTCDA Hybrid Heterojunction Synapse with Efficient Photoelectric Dual Modulation and Versatility

Abstract

Just as biological synapses provide basic functions for the nervous system, artificial synaptic devices serve as the fundamental building blocks of neuromorphic networks; thus, developing novel artificial synapses is essential for neuromorphic computing. By exploiting the band alignment between 2D inorganic and organic semiconductors, the first multi-functional synaptic transistor based on a molybdenum disulfide (MoS 2 )/perylene-3,4,9,10-tetracarboxylic dianhydride (PTCDA) hybrid heterojunction, with remarkable short-term plasticity (STP) and longterm plasticity (LTP), is reported. Owing to the elaborate design of the energy band structure, both robust electrical and optical modulation are achieved through carriers transfer at the interface of the heterostructure, which is still a challenging task to this day. In electrical modulation, synaptic inhibition and excitation can be achieved simultaneously in the same device by gate voltage tuning. Notably, a minimum inhibition of 3% and maximum facilitation of 500% can be obtained by increasing the electrical number, and the response to different frequency signals indicates a dynamic filtering characteristic. It exhibits flexible tunability of both STP and LTP and synaptic weight changes of up to 60, far superior to previous work in optical modulation. The fully 2D MoS 2 /PTCDA hybrid heterojunction artificial synapse opens up a whole new path for the urgent need for neuromorphic computation devices.

Reconfigurable Logic‐in‐Memory and Multilingual Artificial Synapses Based on 2D Heterostructures

“…Figure 4e shows the weight change of the excitatory PSC as a function of the presynaptic input pulse with the amplitude of 4 V and base of 0 V. As the presynaptic input pulse width increases from 1µs to 100 ms, the weight change shows a monotonous increase trend from 5% up to over ≈10 4 % as more and more carriers being captured into the PO x trapping layer, resulting in a stronger effect for Fermi level movement. The largest long‐term synaptic weight change reaches 23 300%, exceeding the previously reported results . Continuous pulse stimulations are applied to the device to mimic the long‐term potentiation (LTP) and depression (LTD) of synapses, which are essential synaptic functions for neuromorphic computing.…”

Recent Progress in Three‐Terminal Artificial Synapses: From Device to System

“…MoS 2 /perylene‐3,4,9,10‐tetracarboxylic dianhydride (PTCDA) hybrid heterojunction has been used to develop an efficient photoelectric dual‐modulated synaptic transistor . This 2D inorganic/organic artificial synapse could function by both electrical and optical modulation, and achieved IPSC, EPSC, PPD, PPF, and SRDP.…”

“…h) STP ( V bg = −20 V) to LTP ( V bg = 0 V) transition by V bg modulation. Reproduced with permission . Copyright 2018, John Wiley and Sons.…”

2D Layered Materials for Memristive and Neuromorphic Applications

“…Phase change memory materials have been widely used in memory [167][168][169] and neuromorphic computing. [69] Copyright 2019, John Wiley & Sons, Inc. d-f) Reproduced with permission. This would inspire researchers among 2D community to explore distinct Figure 10.…”

“…Memristive devices relying on charge-trapping effect [64][65][66][67][68][69][70] at the interface are not suitable for development of robust devices, as it is difficult to control the trapping/detrapping process in a reliable way. The unique physical properties that 2D layered materials and vdW heterostructure possess have not been fully exploited for designing neuromorphic devices with new working principles.…”