Donor Engineering Tuning the Analog Switching Range and Operational Stability of Organic Synaptic Transistors for Neuromorphic Systems

Abstract

Organic artificial synapses are becoming the most desirable format for neuromorphic computing due to their highly tunable resistive states. However, repressively low analog switching range, inferior memory retention, and operational instability greatly hinder the further development of organic synapses. Herein, two donor-acceptor copolymers consisting of electrondeficient isoindigo coupled with variable donating moieties for three-terminal organic synaptic transistors (TOSTs) are reported. It is found that the synaptic function and device stability of TOSTs are significantly improved by enhancing the electron-donating strength of donor units. Polymer alkylated isoindigo-bisethylenedioxythiophene exhibits high analog switching range of 170 ×, two orders of magnitude higher than that of normal organic neuromorphic devices. They also demonstrate excellent memory retention of over 5 × 10 3 s, low switching energy of 13 fJ, and ultrahigh operational stability with 99% of its original current after 100 000 write-read events in air. Furthermore, the high viability of strong donor strategy is showcased by demonstrating flexible TOSTs with stable synaptic function after repeated mechanical bending as well as organic synapses capable of simulating image information processing. Overall, this work highlights the advantages of the strong donor functionalization strategy to boost the synaptic performance and device stability of TOSTs.

Molecularly Hybridized Conduction in DPP‐Based Donor–Acceptor Copolymers toward High‐Performance Iono‐Electronics

“…For OECTs, the gate voltage was applied from −0.8 to 0.2 V and the source–drain voltage was set to −0.6 V (unless otherwise indicated). The volumetric capacitance ( C* ) for each polymer was obtained using cyclic voltammetry in respective electrolytes, [ 64 ] and a 4.5 mm‐wide electrochemical cell was used to contain the liquid electrolytes during the measurements.…”

n-Type Organic Electrochemical Transistors with High Transconductance and Stability

“…In addition to stable operation, the shelf-life of polymers in the film form is another critical issue for applications of OECTs . Film properties are prone to change over time depending on the storage environment, such as moisture, temperature, and oxygen .…”

“…27 In addition to stable operation, the shelf-life of polymers in the film form is another critical issue for applications of OECTs. 28 Film properties are prone to change over time depending on the storage environment, such as moisture, temperature, and oxygen. 29 Long shelf-life in ambient conditions would ensure that device characteristics are maintained from the time of production to the one of use.…”

Ultraviolet-driven metal oxide semiconductor synapses with improved long-term potentiation

“…17–19 This hinders improvements of bio-inspired circuits with long memory retention as a prerequisite and encourages further exploration for better tuning the active materials and driven methods. For instance, Zhao et al have recently applied a donor engineering technique on organics-based synaptic transistors and obtained better LTP retention over 5 × 10 3 s. 20 Apart from organics as the active materials, other materials with distinct features may hold the key to more superior LTP characteristics.…”