Organic Logic Circuits Research Articles

Controllable-doping ambipolar conjugated polymeric semiconductors towards simplified-constructed organic logic circuits with excellent comprehensive performance

Organic electronics aims to simplify the construction of high-performance basic logic circuits for various applications. Ambipolar organic semiconductors, particularly ambipolar conjugated polymers, offer distinct advantages of easy solution-printing-based fabrication and low-cost development of large-area organic circuits. However, the narrow bandgaps of intrinsic ambipolar polymers result in the low current on/off ratio (generally 102–103), impeding the generation of output signals with high accuracy and immunity, which are critical requirements for potential logic circuit applications. The quasi-unipolar transport properties for pristine well-balanced ambipolar polymers were obtained using a controllable-doping process, which resulted in a significant increase in current on/off ratios (105–107) for both p-channel and n-channel thin-film transistors. Furthermore, large-area organic logic circuits such as NOT, NOR, and NAND gates were constructed using a direct writing technique based on the same ambipolar conjugated polymer films with superior p- and n-conducting channels by the controllable-doping process, demonstrating excellent overall performance with a high gain value of ∼150, signal noise margins of 68% and fast response to input voltages. This study provides valuable guidelines for improving the on/off ratio of ambipolar materials by implementing the doping strategy, further promoting the possibility of practical applications in solution-printed integrated organic circuits.

基于6,13-双氰基并五苯一维滑移堆积微米带状晶体 的双极性电荷传输

Featuring small charge transport scattering, mesoscale size, and easy fabrication, one-dimensional self-assembled micro/nanomaterials (1D-MNMs) based on organic π-conjugated systems can be facilely incorporated into integrated microcircuits. Although tremendous progress has been made in 1D-MNMs based on p- or n-channel organic semiconductors, examples of lD-MNMs based on ambipolar organic semiconductors are scarce. Herein, we achieved a novel 1D-MNM based on 6,13-dicyanopentacene (DCP) with a 1D slipped stacking motif using the physical vapor transport method. The DCP-based 1D-MNM showed outstanding, well-balanced ambipolar charge transport with electron and hole mobilities of up to 0.34 and 0.38 cm2 V−1 s−1, respectively, which are among the best ambipolar transport characteristics of 1D-MNMs. Furthermore, a complementary inverter based on the ambipolar 1D-MNM of DCP was also constructed with a gain of up to 7, indicating potential application in organic logic circuits.

Behavioral modeling for low-voltage pentacene-based OTFTs and their implementations for organic logic circuits

We present a behavioral compact model and its implementation for low-voltage pentacene-based organic thin film transistors (OTFTs) using industry standard BSIM4 (Berkeley Short-channel IGFET Model) in LTspice platform. First, we simplify the number of BSIM4 model parameters according to the device structure. On the other hand, we adapt the BSIM4 mobility equation to OTFT and also involve the off-current using two behavioral current sources. Then, we perform metaheuristics-based optimization to extract the related BSIM4 model parameters together with additional four parameters, introduced in this work, fitting the modified model to the experimental data of an OTFT, using pentacene active layer. Finally, we implement the behavioral compact model in LTspice and validate its usage for low-voltage pentacene-based OTFTs comparing the experimental and modeled current–voltage curves. In this study, we also successfully simulate OTFT implementations of a Pseudo-E inverter, a Pseudo-E NAND gate, and a 1-bit full adder circuit based on NAND gates using our behavioral OTFT model and then investigate the static and dynamic performance parameters of these circuits. The supply voltage is 3 V and maximum frequency of the inputs is 500 Hz in the simulations.

Solution-processed ambipolar organic thin-film transistors and inverters in a single substrate through self-assembled monolayer-treated electrodes

Self-assembled monolayer-treated source–drain electrodes enabled the development of high-performance ambipolar organic thin-film transistors using a donor–acceptor-type polymer, PNDI-TVT, and a complementary-like inverter on a single substrate.

Electrically Reconfigurable Organic Logic Gates: A Promising Perspective on a Dual‐Gate Antiambipolar Transistor (Adv. Mater. 15/2022)

Multifunctional Logic Circuits In article number 2109491, Yutaka Wakayama and co-workers demonstrate electrically reconfigurable organic logic circuits using a dual-gate anti-ambipolar transistor. The transistor shows a negative differential transconductance even at room temperature. This unique feature achieves five two-input logic gate operations with “only a transistor”. Such logic operations are not obtainable in conventional transistors. The device concept will provide a way of realizing multifunctional organic logic circuits using a simple circuit design.

Electrically Reconfigurable Organic Logic Gates: A Promising Perspective on a Dual‐Gate Antiambipolar Transistor

AbstractElectrically reconfigurable organic logic circuits are promising candidates for realizing new computation architectures, such as artificial intelligence and neuromorphic devices. In this study, multiple logic gate operations are attained based on a dual‐gate organic antiambipolar transistor (DG‐OAAT). The transistor exhibits a Λ‐shaped transfer curve, namely, a negative differential transconductance at room temperature. It is important to note that the peak voltage of the drain current is precisely tuned by three input signals: bottom‐gate, top‐gate, and drain voltages. This distinctive feature enables multiple logic gate operations with “only a single DG‐OAAT,” which are not obtainable in conventional transistors. Five logic gate operations, which correspond to AND, OR, NAND, NOR, and XOR, are demonstrated by adjusting the bottom‐gate and top‐gate voltages. Moreover, varying the drain voltage makes it possible to reversibly switch two logic gates, e.g., NAND/NOR and OR/XOR. In addition, the DG‐OAATs show a high degree of stability and reliability. The logic gate operations are observed even months later. The hysteresis in the transfer curves is also negligible. Thus, the device concept is promising for realizing multifunctional logic circuits with a simple transistor configuration. Hence, these findings are expected to surpass the current limitations in complementary metal−oxide−semiconductor devices.

Tailored Polymer Gate Dielectric Engineering to Optimize Flexible Organic Field-Effect Transistors and Complementary Integrated Circuits.

The increasing demand for solution-processed and flexible organic electronics has promoted the fabrication of integrated logic circuits using organic field-effect transistors (OFETs) instead of fundamental unit devices. This has been made possible through the rapid development of materials and processes in the past few decades. It is important for the p- and n-type OFETs using different organic semiconductors (OSCs) to have complementarily matched electrical characteristics, which significantly improve the performance of organic logic circuits. In this study, an efficient strategy to optimize the performance of flexible organic electronics, such as OFETs and complementary inverters, is proposed using a combination of polymer insulators tailored to each OSC type. Photopatternable soluble copolyimides (ScoPIs), which exhibit excellent insulating properties and chemical resistance, are synthesized and applied as gate dielectric layers in the OFETs. The material and electrical properties are systematically investigated by varying the molecular ratio of ScoPIs to determine the optimal conditions for each OFET type. As a result, complementary inverters report 1.67 times higher integration density compared to the conventional ones while maintaining gain, switching threshold, and static noise margin of 23.7 V/V, 22.1 V, and 12.1 V, respectively, at a supply voltage of 40 V. The flexible complementary inverters are successfully demonstrated by fully exploiting the advantages of ScoPIs.

Flexible, high mobility short-channel organic thin film transistors and logic circuits based on 4H\u201321DNTT

The low mobility and large contact resistance in organic thin-film transistors (OTFTs) are the two major limiting factors in the development of high-performance organic logic circuits. Here, solution-processed high-performance OTFTs and circuits are reported with a polymeric gate dielectric and 6,6 bis (trans-4-butylcyclohexyl)-dinaphtho[2,1-b:2,1-f]thieno[3,2-b]thiophene (4H–21DNTT) for the organic semiconducting layer. By optimizing and controlling the fabrication conditions, a high saturation mobility of 8.8 cm2 V−1 s−1 was demonstrated as well as large on/off ratios (> 106) for relatively short channel lengths of 15 μm and an average carrier mobility of 10.5 cm2 V−1 s−1 for long channel length OTFTs (> 50 μm). The pseudo-CMOS inverter circuit with a channel length of 15 μm exhibited sharp switching characteristics with a high signal gain of 31.5 at a supply voltage of 20 V. In addition to the inverter circuit, NAND logic circuits were further investigated, which also exhibited remarkable logic characteristics, with a high gain, an operating frequency of 5 kHz, and a short propagation delay of 22.1 μs. The uniform and reproducible performance of 4H–21DNTT OTFTs show potential for large-area, low-cost real-world applications on industry-compatible bottom-contact substrates.

Functionalization of Polymer Dielectrics: Functionalization of Low‐k Polyimide Gate Dielectrics with Self‐Assembly Monolayer Toward High‐Performance Organic Field‐Effect Transistors and Circuits (Adv. Mater. Interfaces 11/2021)

In article number 2100217, Jie Li, Ye Zou, Deyang Ji, Liqiang Li, and co-workers report the functionalization of polyimide dielectrics with orderly self-assembly monolayer, which promotes ordered growth of the semiconductor for enhancing the device performance by an order of magnitude. Furthermore, organic logic circuits are manufactured using modified polyimide as insulating layers.

Functionalization of Low‐k Polyimide Gate Dielectrics with Self‐Assembly Monolayer Toward High‐Performance Organic Field‐Effect Transistors and Circuits

AbstractThe functionalization of polymer dielectrics with self‐assembly monolayer is still a big issue to be resolved due to the lack of particular anchoring sites on their surface for specific binding. To this end, hydroxyl groups are a kind of commonly used anchoring sites, which can be effectively produced on polymer surface by oxygen plasma treatment. In this work, the modification methods are investigated and the assembly conditions of self‐assembly monolayer are characterized on the surface of low‐k polyimide (PI) gate dielectric layers. As a result, the device performance can be enhanced by an order of magnitude under the optimal modified state compared with the initial state. In addition, the charge transport mechanism of organic semiconductor on PI surface is studied through temperature‐variable experiments. Furthermore, organic logic circuits (NAND gate, NOR gate, inverter, and oscillator) are manufactured using modified PI as insulating layers. The functionalization of polymer dielectrics with self‐assembly monolayer offers an effective strategy to improve the device performance in organic electronics.

Improving Both Electron and Hole Mobilities of an Ambipolar Polymer by Integrating Sodium Sulfonate‐Tethered Alkyl Side Chains†

Summary of main observation and conclusionHigh performance ambipolar organic semiconductors are highly desirable for organic logic circuits. Herein, we demonstrate the integration of sodium sulfonate (SS)‐tethered sidechains into a diketopyrrolopyrrole‐based ambipolar polymer (PDPP3T) can simultaneously improve its hole and electron transport performances either parallel or perpendicular to polymer film. Three SS‐functionalized polymers (PDPP3T‐xSS, x = 0.025, 0.05 and 0.10) were synthesized and studied. It was found that SS functionalization can reinforce interchain π‐π interactions, slightly lower frontier orbital energy levels, produce more rod‐like structures in film, and change chain‐packing from edge‐on to face‐on fashion, but has little influence on thermal properties. More interestingly, organic field‐effect transistors reported hole mobility of 0.27 ± 0.066 cm2·V–1·s–1 and electron mobility of 0.038 ± 0.016 cm2·V–1·s–1 for PDPP3T, while increased 2.4 and 5 folds to 0.64 ± 0.087 and 0.19 ± 0.051 cm2·V–1·s–1 for PDPP3T‐0.025SS, respectively. Moreover, PDPP3T‐xSS devices displayed reduced threshold voltages for both hole and electron transports. Meanwhile, space charge‐limited current method found SS functionalization achieved an order of magnitude increase in electron mobility and slight enhancement in hole mobility transporting perpendicular to polymer film. In‐depth investigations suggest such enhancements may originate from the joint actions of chain‐stacking modulation and ionic doping effect.

Multi-Stage Organic Logic Circuits Using Via-Hole-Less Metal Interconnects

Multi-metal interconnection is a crucial technology for the development of large-scale integrated circuits (ICs). However, organic semiconductors are not robust enough to be compatible with conventional lithography-and-etching-based via-forming methods. Thus, an alternative metal interconnect method is required for successful organic IC implementation. In-situ patterning of a dielectric polymer through a shadow mask while depositing in vapor phase possibly addresses the issues in both solvent susceptibility and process complexity. Here we report multi-stage organic logic circuits with a multi-level metal interconnection scheme based on patterned interlayer dielectrics via vapor phase deposition. We implement an exclusive OR circuit composed of four 2-input NAND gates and three-level metal interconnections to demonstrate the potential of the proposed solvent-free metal interconnection scheme.

Organic-based inverters: basic concepts, materials, novel architectures and applications.

While organic materials have demonstrated industry-leading performances in a wide array of electronic applications (including OLEDs and OPVs), their use for integration into electronic circuits has been so far limited, in spite of their potential for portable, flexible, light-weight, low-cost applications. However, recent advances in organic (semi)conductors and novel designs in organic field-effect transistors and hybrid systems have reaffirmed the potential of organic logic circuits. This review article provides an overview of organic-based inverter operation and considers all aspects of such circuits including their active layer, processing methods, hybrid organic/inorganic inverters, novel architectures and potential applications.

Multisubstituted Azaisoindigo-Based Polymers for High-Mobility Ambipolar Thin-Film Transistors and Inverters.

Ambipolar semiconducting materials have great potential in complementary-like organic logic circuits. Accessing such logic circuits demands balanced hole and electron mobilities. However, the lack of ambipolar high-mobility polymer semiconductors with balanced charge carrier-transporting properties precludes the rapid development of organic logic circuits. In this context, structural modification of semiconductor materials to enhance the electron/hole transport is of great urgency. Herein, a multifunctionalization strategy is used to achieve this goal. Combined electron-withdrawing moieties involving fluorine and pyridinic nitrogen atoms can not only reduce the frontier molecular orbital energies but also planarize the polymer backbone, demonstrating synergetic effects on the control over the carrier injection process at the metal-semiconductor interface and microstructure-sensitive charge transport in the channel. A balanced ambipolar behavior with electron/hole mobilities of 3.88/3.44 cm2 V-1 s-1 was observed, and complementary-like inverters with high gains of greater than 200 were achieved. Microstructure and thin-film morphology were characterized to further reveal the relationship between device performances and macroscopic observables. This multifunctionalization strategy bodes well for developing new ambipolar semiconducting materials.

Two-dimensional organic single-crystalline p-n junctions for ambipolar field transistors

Two-dimensional single-crystalline p-n junctions of organic semiconductors (pn-2DCOSs) show great potential in organic logic circuits due to their single crystal nature and excellent ambipolar charge transport. However, there are only few reports on pn-2DCOSs because it is difficult to obtain such highly ordered structure in p-n junction. Herein, a novel and effective solution processing method of secondary transfer technology based on the facile drop casting is used to fabricate devices of pn-2DCOSs based on C8-BTBT (p-type) and TFT-CN (n-type) successfully. The high-performance ambipolar field transistors based on such ultrathin pn-2DCOSs with several molecular layers thickness show well-balanced ambipolar charge transport behaviors with hole mobility as high as 0.43 cm2 V−1 s−1 and electron mobility up to 0.11 cm2 V−1 s−1, respectively. This work is essential for studying the intrinsic properties of organic p-n junctions and achieving high performance in organic complementary circuits.

Two-in-One Device with Versatile Compatible Electrical Switching or Data Storage Functions Controlled by the Ferroelectricity of P(VDF-TrFE) via Photocrosslinking

Organic electronics demand new platforms that can make integrated circuits and undergo mass production while maintaining diverse functions with high performance. The field-effect transistor has great potential to be a multifunctional device capable of sensing, data processing, data storage, and display. Currently, transistor-based devices cannot be considered intrinsic multifunctional devices because all installed functions are mutually coupled. Such incompatibilities are a crucial barrier to developing an all-in-one multifunctional device capable of driving each function individually. In this study, we focus on the decoupling of electric switching and data storage functions in an organic ferroelectric memory transistor. To overcome the incompatibility of each function, the high permittivity needed for electrical switching and the ferroelectricity needed for data storage become compatible by restricting the motion of poly(vinylidene fluoride-trifluoroethylene) via photocrosslinking with bis-perfluorobenzoazide. The two-in-one device consisting of a photocrosslinked ferroelectric layer exhibits reversible and individual dual-functional operation as a typical transistor with nonvolatile memory. Moreover, a p-MOS depletion load inverter composed of the two transistors with different threshold voltages is also demonstrated by simply changing only one of the threshold voltages by polarization switching. We believe that the two-in-one device will be considered a potential component of integrated organic logic circuits, including memory, in the future.

Negative transconductance in multi-layer organic thin-film transistors

Negative transconductance (NTC) refers to the phenomenon of the N-shape transfer characteristic appearing with a current peak and valley. It has been extensively studied in the past few decades due to its applications in logic and memory devices. Here, we observe unique antibipolar transfer characteristics and NTC behavior in multi-layer 2,6-diphenyl anthracene organic thin-film transistors grown on h-BN, which is due to the vertical potential barrier between the charge accumulation region near the substrate and the neutral bulk region under the contacts. The applied extrinsic electric field could effectively modulate the barrier height, resulting in a competition for charge carrier transport between lateral and vertical directions. Based on the NTC and antibipolar properties, a frequency doubler has been fabricated on a single transistor, which provides a new building block for organic logic circuits.

High-performance organic circuits based on precisely aligned single-crystal arrays.

In this paper, we demonstrate high-performance organic logic circuits based on precisely controlled organic single-crystal arrays. Well-aligned microrod shaped 2,7-dioctyl[1]benzothieno[3,2-b][1]benzothiophene (C8-BTBT) single-crystal organic thin-film-transistors (OTFTs) were fabricated via solvent mediated molecular tailoring with a polymeric sacrificial layer, exhibiting saturation mobility of >2 cm2 V−1 s−1. Using this approach, precise placement of organic crystal arrays in a controlled orientation was successfully achieved, enabling the fabrication of OTFT-based inverter circuits with a gain of 1.37 (V V−1). Furthermore, it was demonstrated that, by varying the number of single-crystal microrods, the device dimension and corresponding circuit performance can be modulated. A high-performance inverter operation with various interdigitating single-crystal microrod arrays can thus be achieved.

Low operating voltage organic transistors and circuits with anodic titanium oxide and phosphonic acid self-assembled monolayer dielectrics

We fabricated organic thin-film transistors (OTFTs) with sub-1 V driving voltage enabled by a hybrid dielectric comprising high-k amorphous titanium oxide (TiOx) and a phosphonic acid self-assembled monolayer (SAM). The p-type OTFTs show a high on/off ratio (105), a near 0 V threshold voltage (−0.09 V), and a high mobility of 1.2 cm2/Vs when operated at 1 V. These OTFTs are readily employed in circuit applications, and we show pseudo-CMOS and CMOS inverters operating at 0.5 V as basic building blocks of low-voltage advanced organic logic circuits. We fabricate a five-stage CMOS ring oscillator that displays clear oscillation characteristics at a driving voltage of 0.5 V to highlight the potential of our hybrid dielectric for ultra-low-voltage integrated plastic circuitry.

High-speed organic transistors with three-dimensional organic channels and organic rectifiers based on them operating above 20 MHz

Three-dimensional organic transistors (3D-OFETs) comprising vertical short channels are developed to raise the operational speed of organic transistors. The devices with a short-channel length of 0.8μm and reduced parasitic capacitance operate at up to 20MHz with an applied drain voltage of −15V. Organic rectifiers based on the diode-connected 3D-OFETs are also demonstrated to operate at above 20MHz, even with an applied effective voltage of about 4V, which is higher than the speed of radio frequency identification tags of 13.56MHz required in near field communication. These techniques boost the performance of organic transistors and can help to realize the breakthrough for practical applications of organic logic circuits used as key components in various flexible or plastic devices.