Photonic Synapses with Ultra‐Low Energy Consumption Based on Vertical Organic Field‐Effect Transistors

Abstract

synaptic functions is fundamental to the realization of brain-like computing.Recently, many research advances have been made in the field of artificial synapses, [4] such as memristors, [5] phasechange memory, [6] and field-effect transistors [7] have been exploited to simulate synaptic behaviors. Notably, interest has arisen in organic synaptic transistors, [8] which can combine the advantages of organic electronics, such as low cost, flexibility, and ease of solution fabrication, together with the benefit of multi-terminal synaptic devices for more controllable test parameters. [9] Compared to conventional planar transistors, vertical organic field-effect transistors (VOFETs) are structurally different. [10] Attributing to their adjustable channel lengths determined by the thickness of active layers, they can be simply controlled to sub-micron level or nanometer level in channel length. Small channel length implies high on-state conductance and low voltage operation for the device. [11] The characteristics of VOFETs are consistent with requirements for low voltage operation and low energy consumption of artificial synaptic devices. Furthermore, VOFETs have some potentially unique advantages. Large-scale integration of devices can be achieved through crossbar stacking owing to the vertical electrode placement. The vertical current flow in VOFET could be more tolerant of channel cracks caused by device bending or stretching, [12] which provides a promising approach for the next generation of flexible microelectronic devices.Here, we have fabricated photonic synaptic devices with the structure of VOFETs for the first time. In our work, vertical structure transistors have been designed and constructed, in which networks of single-walled carbon nanotubes (SWCNTs) served as the bottom electrode, CsPbBr 3 quantum dots (QDs) were selected as light-harvesting material, a p-type organic polymer semiconductor, poly[2,5-bis(2-octyldodecyl)pyrrolo [3,4c]pyrrole-1,4(2H,5H)-dione-3,6-diyl)-alt-(2,2′;5′,2″;5‴,2‴quaterthiophen-5,5‴-diyl)] (PDPP4T), was used as the channel material. PEDOT: PSS (conductive polymer) acted as the top transparent electrode, which could transmit light signals for synaptic activities owing to its transparency. In this photonic synaptic device, typical functions of biological synapses, such as excitatory post-synaptic current (EPSC), short-term plasticity (STP), and long-term plasticity (LTP), have been successfully Artificial synapses have shown great potential in the research of artificial intelligence and brain-like computing. Artificial synaptic devices based on vertical organic field-effect transistors (VOFETs) exhibit shorter carrier transmission distances and more stable source-drain currents than conventional planar organic transistors due to their smaller channel lengths. By taking advantage of the vertical structure, low working voltage can be achieved. Here, vertical synaptic devices with working voltage as low as 10 µV and ultra-low power consumption (≈1.3 fJ per spike) are proposed....

Lead‐Free Perovskites‐Based Photonic Synaptic Devices with Logic Functions

“…Therefore, small A 2 value could be obtained at long Δ t when the second optical pulse was used to the device. In addition, the experimental data of PPF index at different Δ t were fitted by the double exponential function as follows [ 43–45 ] where C 1 and C 2 are the beginning facilitation values of the fast and slow phases, respectively. τ 1 and τ 2 are the relaxation time of the fast and slow phases, respectively.…”

“…Therefore, small A 2 value could be obtained at long Δt when the second optical pulse was used to the device. In addition, the experimental data of PPF index at different Δt were fitted by the double exponential function as follows [43][44][45] PPF index C…”

Self‐Assembled Nanostructures of Quantum Dot/Conjugated Polymer Hybrids for Photonic Synaptic Transistors with Ultralow Energy Consumption and Zero‐Gate Bias

“…[ 40–45 ] In particular, perovskite‐based composites present the advantages of affordability, processability, and superior optoelectronic properties, including a high photoluminescence quantum yield, narrow‐band emission, high dielectric constants, and a tunable optical bandgap. [ 46–49 ]…”

The Role of the Internal Capacitance in Organic Memristive Device for Neuromorphic and Sensing Applications

“…Different groups reported synaptic-like devices using nanoscale magnetic materials developing spintronic devices, [12,13] metal oxides, [14][15][16] or organic materials based on redox reactions [17][18][19] and ion permeation. [20][21][22] The increasing interest in organic materials demonstrating basic forms of neuroplasticity has recently driven the development of different approaches for reducing the operation voltage ranges [23,24] and for increasing the networks density. [25] Short term memory and adaptation functions have been reported in different organic devices [26][27][28][29] who demonstrated the capability of performing paired pulse facilitation or depression (PPF or PPD, respectively), while spatio-temporal neuronal integration has been demonstrated in devices with a multigate configuration [27] or in NbO x volatile memristors.…”