Solution-Processable Anion-doped Conjugated Polymer for Nonvolatile Organic Transistor Memory with Synaptic Behaviors

Abstract

Brain-inspired synaptic transistors have been considered as a promising device for next-generation electronics. To mimic the behavior of a biological synapse, both data processing and nonvolatile memory capability are simultaneously required for a single electronic device. In this work, a simple approach to realize a synaptic transistor with improved memory characteristics is demonstrated by doping an ionic additive, tetrabutylammonium perchlorate (TBAP), into an active polymer semiconductor without using any extra charge storage layer. TBAP doping is first revealed to improve the memory window of a derived transistor memory device from 19 to 32 V (∼68% enhancement) with an on/off current ratio over 10 3 at V G = −10 V. Through morphological analysis and theoretical calculations, it is revealed that the association of anion with polymers enhances the charge retention capability of the polymer and facilitates the interchain interactions to result in improved memory characteristics. More critically, the doped device is shown to successfully mimic the synaptic behaviors, such as paired-pulse facilitation (PPF), excitatory and inhibitory postsynaptic currents, and spike-rate dependent plasticity. Notably, the TBAP-doped device is shown to deliver a PPF index of up to 204% in contrast to the negligible value of an undoped device. This study describes a novel approach to prepare a synaptic transistor by doping conjugated polymers, which can promote the future development of artificial neuromorphic systems.

Neuromorphic bioelectronics based on semiconducting polymers

“…Yu et al implemented a synaptic transistor that displayed EPSC, PPF, spike-rate dependent plasticity, and potentiation/depression without using any extra charge storage. 107 They suggested that ionic doping, instead of a charge storage layer, could impart synaptic behavior to a typical transistor. Figure 12C illustrates schematically a bottom-gate/top-contact OFET based on the p-channel dominant ambipolar copolymer poly (thienothiophene-co-1,4-diketopyrrolo[3,4-c]pyrrole) (PDBT-co-TT).…”

“…Reproduced with permission. 107 Copyright 2020, American Chemical Society. (E) Configuration of an electret-based synaptic transistor and chemical structures of the components.…”

2D Heterostructure for High‐Order Spatiotemporal Information Processing

“…Such issue is owing to the fundamental constraints in von Neumann computer architecture and the sequential Boolean logic. [9][10][11] Human's brain can perform a variety of complicated recognition and perception functions, such as abstract reasoning, linguistic comprehension, and motor control, based upon the high-level computing capability. It is mainly originated from the operation architecture of brain: the connection strength of 10 15 synapses between 10 11 neurons is modulated in a massively parallel, fault-tolerant and adaptive fashion, through which infor-the synaptic device, if only two competing factors (the potentiation effect by the postsynaptic spike train and spontaneously current decay after experience) determine the synaptic weight modulation, EDE cannot be achieved.…”

Highly Efficient Photo‐Induced Recovery Conferred Using Charge‐Transfer Supramolecular Electrets in Bistable Photonic Transistor Memory

“…On the contrary, supramolecules feature complexation between an appropriate polymer matrix and small molecule using non-covalent interactions, such as electrostatic association, hydrogen bonding, metal-ligand coordination, and chargetransfer (CT) to form a copolymer-like structure. [10][11][12] The versatile combination and facile process offered by supramolecules allow their widespread application. CT interactions between electron-rich and electron-deficient aromatic molecules have been extensively applied in numerous design strategies owing to their inherent and uniform association.…”