Synaptic plasticity functions in an organic electrochemical transistor

Abstract

Synaptic plasticity functions play a crucial role in the transmission of neural signals in the brain. Short-term plasticity is required for the transmission, encoding, and filtering of the neural signal, whereas long-term plasticity establishes more permanent changes in neural microcircuitry and thus underlies memory and learning. The realization of bioinspired circuits that can actually mimic signal processing in the brain demands the reproduction of both short- and long-term aspects of synaptic plasticity in a single device. Here, we demonstrate the implementation of neuromorphic functions similar to biological memory, such as short- to long-term memory transition, in non-volatile organic electrochemical transistors (OECTs). Depending on the training of the OECT, the device displays either short- or long-term plasticity, therefore, exhibiting non von Neumann characteristics with merged processing and storing functionalities. These results are a first step towards the implementation of organic-based neuromorphic circuits.

Molecular Semiconductors for Logic Operations: Dead‐End or Bright Future?

“…Colocation of computation and memory is of great interest because of its efficiency in learning tasks . The ability to temporarily or permanently change electrical conduction by ion diffusion into the channel mimics short‐term or long‐term memory of neurons . Neuromorphic devices do not only imitate the function of neurons they exhibit the decisive advantage of low power consumption per switching event that can be as low as 1.23 × 10 −15 J, a value that rivals with the energy consumption of 10 −14 J per biological synaptic event .…”

“…Neuromorphic devices do not only imitate the function of neurons they exhibit the decisive advantage of low power consumption per switching event that can be as low as 1.23 × 10 −15 J, a value that rivals with the energy consumption of 10 −14 J per biological synaptic event . The retention time can be tailored from a few seconds in PEDOT:PSS to several hours in polymers that change conformation upon charging . Such applications and underlying concepts are unprecedented and widen considerably the scope of organic semiconductors toward open fields.…”

Mechanisms for Enhanced State Retention and Stability in Redox‐Gated Organic Neuromorphic Devices

“…[6] However, these algorithms have proven to be computationally intensive, requiring >100 graphics processing such as poly (3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS), due to the low voltages required to modulate the material's conductance. [32][33][34][35][36] When implemented in a three-terminal architecture as an NVRM, PEDOT:PSS devices show exceptionally low switching energies (10 pJ for a 100 µm 2 device) in addition to linear and symmetric conductance response required for "blind" weight update (i.e., not involving a read). [32][33][34][35][36] When implemented in a three-terminal architecture as an NVRM, PEDOT:PSS devices show exceptionally low switching energies (10 pJ for a 100 µm 2 device) in addition to linear and symmetric conductance response required for "blind" weight update (i.e., not involving a read).…”

Orientation selectivity with organic photodetectors and an organic electrochemical transistor

“…Various neuromorphic functions have been recently reported in OECTs, such as short-and long term plasticity and orientation selectivity. [22][23][24] Among the above mentioned neuromorphic functions, orientation selectivity is of particular interest, because it opens the door for novel, spatial concepts of information processing in organic bioelectronic devices. Orientation selectivity has been studied extensively in the past decades and is related to visual perception.…”