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Recent Advances in Isoindigo-Inspired Organic Semiconductors
摘要： Over the past decade, isoindigo has become a widely used electron-deficient subunit in donor-acceptor organic semiconductors, and these isoindigo-based materials have been widely used in both organic photovoltaic (OPV) devices and organic field effect transistors (OFETs). Shortly after the development of isoindigo-based semiconductors, researchers began to modify the isoindigo structure in order to change the optoelectronic properties of the resulting materials. This led to the development of many new isoindigo-inspired compounds; since 2012, the Kelly Research Group has synthesized a number of these isoindigo analogues and produced a variety of new donor-acceptor semiconductors. In this Personal Account, recent progress in the field is reviewed. We describe how the field has evolved from relatively simple donor-acceptor small molecules to structurally complex, highly planarized polymer systems. The relevance of these materials in OPV and OFET applications is highlighted, with particular emphasis on structure-property relationships.
关键词： isoindigo,organic field effect transistors,organic materials,organic photovoltaics,conjugated polymers
更新于2025-09-23 15:21:01
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Chemical and Biomolecule Sensing with Organic Field-Effect Transistors
摘要： The strong and controllable chemical sensitivity of organic semiconductors (OSCs) and the amplification capability of transistors in circuits make use of OSC-based field-effect transistors compelling for chemical sensors. Analytes detected and assayed range from few-atom gas-phase molecules that may have adverse health and security implications to biomacromolecules (proteins, nucleic acids) that may be markers for physiological processes and medical conditions. This review highlights recent progress in organic field-effect transistor (OFET) chemical sensors, emphasizing advances from the past 5 years and including aspects of OSC morphology and the role of adjacent dielectrics. Design elements of the OSCs and various formats for the devices are illustrated and evaluated. Challenges associated with the present state of the art and future opportunities are also discussed.
关键词： organic field-effect transistors,organic semiconductors,dielectrics,biomacromolecules,chemical sensors
更新于2025-09-23 15:21:01
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MoS <sub/>2</sub> Assisted Self-Assembled Poly (3-hexylthiophene) Thin Films at Air/Liquid Interface for High-Performance Field-Effect Transistors under Ambient Condition
摘要： It is a key challenge to achieve long-range ordering in nanoscale morphology of π-conjugated polymers for efficient charge transport in organic electronic devices. The long-range ordering and aggregation in poly (3-hexylthiophene) (P3HT) has been accomplished by introducing two dimensional (2D) Molybdenum disulfide (MoS2) nanosheets in polymer matrix followed by ultrasonication in chloroform. Thin films of synthesized P3HT/MoS2 nanocomposites having various fractions of MoS2 in the P3HT matrix have been fabricated on the air/liquid interface. The UV visible absorption spectroscopy has been employed to investigate the nature of aggregation and exciton bandwidth in the resultant films deposited at the air/liquid interface. Moreover, grazing incidence X-ray diffraction (GIXD) analysis, and atomic force microscopy (AFM), reveal the long-range ordering and highly crystalline thin films with the edge-on orientation of polymer chains over the substrate. Further, the impact of aggregation, morphology, and orientation on macroscopic charge transport performance is elaborately estimated by fabricating organic field-effect transistors (OFETs). The hole mobility as high as 0.160 ± 0.007 cm2V-1s-1, has been achieved for P3HT/MoS2 (1%) nanocomposite under ambient condition.
关键词： organic field-effect transistors,MoS2,π-conjugated polymers,nanocomposites,P3HT,charge transport
更新于2025-09-23 15:19:57
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NIR polymers and phototransistors
摘要： A novel bisthiophene-fused diketopyrrolopyrrole unit (4,11-bis(2-octyldodecyl)-7H,14H-thieno[30,20:7,8]indolizino[2,1-a]thieno[3,2-g]indolizine-7,14-dione, BTI) has been designed as an electron acceptor and used to copolymerize with thiophene and bithiophene as electron donors to construct two D–A conjugated polymers, P1 and P2 via Stille coupling, respectively. The two polymers showed excellent thermal stability, broad light absorption and a narrow energy band gap. P1 and P2 were used to fabricate organic field-effect transistors (OFETs) to evaluate their charge transport characteristics. P2 showed much better hole transport performance with a mobility of 0.1 cm2 V?1 s?1. Near-infrared (NIR) phototransistors were also fabricated by using the two polymers blended with PC71BM as the active layer. With illumination of 35 mW cm?2 at a wavelength of 850 nm, the photocurrent/dark-current ratio (P) and photoresponsivity (R) of the phototransistor based on P1/PC71BM were 3.6 × 104 and 270 A W?1, respectively. For P2/PC71BM, P was 2.5 × 104 and R reached 2420 A W?1.
关键词： phototransistors,photoresponsivity,organic field-effect transistors,diketopyrrolopyrrole,NIR polymers,charge transport
更新于2025-09-19 17:15:36
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Bias-stress effects in diF-TES-ADT field-effect transistors
摘要： A systematic analysis of the bias-stress effects in solution-processed organic field-effect transistors is reported. Difluoro 5,11-bis(triethylsilylethynyl) anthradithiophene, a high-performance molecular semiconductor, forms a charge-transport channel and is coupled with injection contacts made of Au, Ag, or Cu. The electrode metal is found to not only greatly affect the switching performances but also drive the response of transistors to the extended applications of gate voltage. The observations are put into the framework of contact-limited transistor model, which holistically assesses the material, geometry, and stress-related contributions.
关键词： Bias stress,Device physics,Contact resistance,DiF-TES-ADT,Organic field-effect transistors
更新于2025-09-19 17:15:36
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Naphthalene Diimide-Based Terpolymers with Controlled Crystalline Properties for Producing High Electron Mobility and Optimal Blend Morphology in All-Polymer Solar Cells
摘要： We report a series of new n-type random copolymers (P(NDI2OD-Se-Th x) where x = 0, 0.5, 0.7, 0.8, 0.9, 1.0) consisting of naphthalene diimide (NDI), selenophene-2,2’-thiophene (Se-Th), and seleno[3,2-b]thiophene (SeTh) to demonstrate their use in producing efficient all-polymer solar cells (all-PSCs) and organic field-effect transistors (OFETs). To investigate the effect of polymer crystallinity on the performance of all-PSCs and OFETs, we tuned the composition of the Se-Th and SeTh moieties in the P(NDI2OD-Se-Th x) polymers, resulting in enhanced crystalline properties with higher Se-Th ratio. Thus, the OFET electron mobility was increased with higher Se-Th ratio, exhibiting the highest value of 1.38×10?1 cm2 V?1 s?1 with P(NDI2OD-Se-Th 1.0). However, the performance of all-PSCs based on PBDB-T:P(NDI2OD-Se-Th x) showed a non-linear trend relative to the Se-Th ratio and the performance was optimized with P(NDI2OD-Se-Th 0.8) exhibiting the highest power coversion efficiency of 8.30%. This is attributed to the stronger crystallization-driven phase separation in all-polymer blends for higher Se-Th ratio. At the optimal crystallinity of P(NDI2OD-Se-Th 0.8) in all-PSCs, the degree of phase separation, domain purity and the electron mobility were optimized, resulting in enhanced charge generation and transport. Our works describe structure-property-performance relationships to design effective n-type polymers in terms of crystalline and electrical properties suitable for both efficient OFETs and all-PSCs.
关键词： organic field-effect transistors,seleno[3,2-b]thiophene,polymer crystallinity,n-type random copolymers,selenophene-2,2’-thiophene,charge generation,all-polymer solar cells,charge transport,naphthalene diimide
更新于2025-09-19 17:13:59
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Influences of Energetically Controlled Dielectric Functionality on Polymer Field-Effect Transistor Performance
摘要： We systematically demonstrated the effects of surface modification of gate dielectrics and the thermal annealing of an ad-deposited polymer semiconducting film on the electrical performance of organic field-effect transistors (OFETs) in which they were incorporated. Chemically or energetically engineered dielectrics were designed by introducing various end-functional groups (CF3, CH3, NH2, Cl, and SH). Poly(dioctyl-quaterthiophene-dioctyl-bithiazole) (PDQDB), consisting of 5,5 ′ -bithiazole and oligothiophene rings, was employed as the polymer semiconductor. We analyzed the PDQDB semiconducting films’ crystalline character, which has an important effect on the FET performance, and confirmed that the crystallinity of the PDQDB semiconducting films was higher in the cases (CF3 and CH3) of low surface energy than in the cases (NH2, SH, and Cl) of high surface energy, yielding μFET values as high as 0.13 and 0.12 cm2 V?1 s?1 for the CF3 and CH3 cases, respectively. Another important observation was the tendency of the μFET value to change depending on the thermal annealing temperature—increasing and decreasing in the cases of surface functionalities with low and high surface energies, respectively. These results could be interpreted on the basis of the differently competitive molecule–molecule and molecule–dielectric surface interactions, where the π–π stacking configuration of the conjugated molecular structures was enhanced on lower-energy surfaces. We also discussed the effect of permanent dipoles for the engineered self-assembled monolayer dielectrics on the threshold and turn-on voltages in the PDQDB FET devices.
关键词： thermal annealing,surface modification,polymer semiconductor,organic field-effect transistors,dielectric functionality
更新于2025-09-12 10:27:22
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A Machine‐Learning Based Design Rule for Improved Open‐Circuit Voltage in Ternary Organic Solar Cells
摘要： Organic solar cells (OSCs) based on ternary blend active layers are among the most promising photovoltaic technologies. To further improve the power conversion efficiency (PCE), the materials selection criteria must be focused on achieving high open-circuit voltage (Voc) through the alignment of the energy levels of the ternary blend active layers. Hence, machine-learning approaches are in high demand for extracting the complex correlation between Voc and the energy levels of the ternary blend active layers, which are crucial to facilitate device design. In the present work, the data-driven strategies are used to generate a model based on the available experimental data and the Voc are then predicted using available machine-learning methods (Random Forest regression and Support Vector regression). In addition, the Random Forest regression is compared with Support Vector regression to demonstrate the superiority of Random Forest regression for Voc prediction. The Random Forest regression is then developed to find the appropriate energy level alignment of ternary OSCs and to reveal the relationship between Voc and electronic features. Finally, an analysis based on the ranking of variables in terms of importance by the Random Forest model is performed to identify the key feature governing the Voc and the performance of ternary OSCs. From the perspective of device design, the machine-learning approach provides sufficient insights to improve the VOC and advances the comprehensive understanding of ternary OSCs.
关键词： organic field-effect transistors,Machine-learning,charge transport mobility.
更新于2025-09-12 10:27:22
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Effect of space charge limited current on performance of organic field-effect transistors
摘要： The crucial parameter that determines the performance of a semiconductor material in organic field-effect transistors (OFETs) is the charge carrier mobility. The conventional method of its determination based on Shockley’s equations can lead to incorrect mobility evaluation due to contact effects. Particularly, in the common staggered OFET architecture (top-contact bottom-gate or bottom-contact top-gate), the space-charge limited current (SCLC) effect in the active layer under/above the source and drain contacts decreases the source-drain current. In this work, we model the effect of SCLC under/above the source and drain electrodes on the OFET apparent mobility (i.e., calculated from the device characteristics) and apparent threshold voltage for different active layer thickness and intrinsic mobility anisotropy. For the saturation regime, we derived simple analytical expressions for transfer characteristics and apparent mobility. Our modeling shows that the apparent OFET mobility is more than five times lower than the intrinsic one for the active layer thicker than 100 nm with mobility anisotropy (along vs across the active layer) higher than 100. While the SCLC effect does not change the apparent threshold voltage, it reveals itself as a kink at near zero voltage in the output characteristics. The proposed model gives analytical expressions for the transfer characteristics and apparent mobility as explicit functions of the intrinsic mobility and the device parameters in the saturation regime and as implicit functions in the linear regime. Our findings provide guidelines for accurate evaluation of the intrinsic mobility in OFETs fabricated in the staggered architecture and for further improvement of OFET performance.
关键词： Organic field-effect transistors,Organic thin-film transistors,Space charge limited current,Contact effects,Modeling
更新于2025-09-11 14:15:04
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Highly sensitive air stable easily processable gas sensors based on Langmuir-Schaefer monolayer organic field-effect transistors for multiparametric H <sub/>2</sub> S and NH <sub/>3</sub> real-time detection
摘要： A combination of low limit of detection, low power consumption and portability makes organic field-effect transistors (OFETs) chemical sensors promising for various applications in the areas of industrial safety control, food spoilage detection and medical diagnostics. However, the OFET sensors typically lack air stability and restoration capability at room temperature. Here we report on a new design of highly sensitive gas sensors based on Langmuir-Schaefer monolayer organic field-effect transistors (LS OFETs) prepared from organosilicon derivative of [1]benzothieno[3,2-b][1]-benzothiophene. The devices fabricated are able to operate in air and allows an ultrafast detection of different analytes at low concentrations down to tens ppb. The sensors are reusable and can be utilized in real-time air quality monitoring systems. We show that a direct current response of the LS OFET can be splitted into the alteration of various transistor parameters, responsible for the interactions with different toxic gases. The sensor response acquiring approach developed allows distinguishing two different gases, H2S and NH3, with a single sensing device. The results reported open new perspectives for the OFET-based gas-sensing technology and pave the way to easy detection of the other types of gases enabling the development of complex air analysis systems based on a single sensor.
关键词： Multiparametric detection,Sensing mechanism,Monolayer organic field-effect transistors,Langmuir-Schaefer monolayers,Chemical sensors
更新于2025-09-11 14:15:04