Study of electrical performance and stability of solution-processed n-channel organic field-effect transistors
TL;DR: In this paper, a solution processed n-channel organic field effect transistors based on [6,6]-phenyl C61 butyric acid methyl ester with high mobility and low contact resistance are reported.
Abstract: Solution processed n-channel organic field-effect transistors based on [6,6]-phenyl C61 butyric acid methyl ester with high mobility and low contact resistance are reported. Ca, Au, or Ca capped with Au (Ca/Au) was used as the top source/drain electrodes. The devices with Ca electrodes exhibit excellent n-channel behavior with electron mobility values of 0.12 cm2/V s, low threshold voltages (∼2.2 V), high current on/off ratios (105–106) and subthreshold slopes of 0.7 V/decade. By varying the channel lengths (25–200 μm) in devices with different metal/semiconductor interfaces, the effect of channel length scaling on mobility is studied and the contact resistance is extracted. The width-normalized contact resistance (RCW) for Au (12 kΩ cm) is high in comparison to Ca (7.2 kΩ cm) or Ca/Au (7.5 kΩ cm) electrodes at low gate voltage (VGS=10 V). However, in the strong accumulation regime at high gate voltage (VGS=30 V), its value is nearly independent of the choice of metal electrodes and in a range of 2.2–2.6 kΩ cm. These devices show stable electrical behavior under multiple scans and low threshold voltage instability under electrical bias stress (VDS=VGS=30 V, 1 h) in N2 atmosphere.
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TL;DR: In this article, the electron mobility of one of the fullerene derivatives was as high as 0.05 cm2/(V)s, suggesting that pyrrolidinofullerenes can be promising n-type semiconductors.
Abstract: We synthesized pyrrolidinofullerenes functionalized with an electron donor or acceptor group via Prato reaction. Their structures were studied using 1H-NMR, FT-IR and MALDI-TOF mass spectrometry. The electronic energy levels were calculated using quantum chemical calculation based on the density functional theory, showing that the lowest unoccupied molecular orbitals were in the range of −3.7 and −3.9 eV. The electron mobility of one of the fullerene derivatives was as high as 0.05 cm2/(V s), suggesting that pyrrolidinofullerenes can be promising n-type semiconductors. The fullerene derivatives were also blended with P3HT to fabricate bulk heterojunction polymer solar cells, and the performance of solar cells as a function of structural variations of the fullerene derivatives was investigated.
2 citations
Cites background or methods from "Study of electrical performance and..."
...Although this mobility of C60-TPA is lower than PCBM [15], it is higher than another pyrrolidinofullerene derivative reported earlier [7]....
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...As shown in Table 1, the devices have rather lower short-circuit current density (Jsc), open-circuit voltage (VOC), and fill-factor (FF) compared to those of PCBMbased devices reported elsewhere....
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...Electron mobility was measured using top-contact organic field-effect transistors [15, 16]....
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01 Dec 2018
TL;DR: In this paper, the effect of varying the semiconductor:polymer blend ratio on the electrical performance and bias-stress stability of the organic field effect transistors (OFETs) with TIPS-Pentacene and polystyrene as semiconductor and polymer combination was reported.
Abstract: We report the effect of varying the semiconductor:polymer blend ratio on the electrical performance and bias-stress stability of the organic field effect transistors (OFETs) with TIPS-Pentacene and polystyrene as semiconductor and polymer combination. Device performance was found to improve with increasing polymer content in the solution. Devices with 1:3 TIPS-Pentacene:polystyrene blend outperformed the other counterparts with high performance, and demonstrated least performance variation with regular 100 transfer measurement cycles. In addition, 1:3 blend devices have shown the least normalized drain current decay of $\sim$ 8.5 % with the bias stress condition of V DS = V GS = -30 V for 2 h, as compared to the 1:1, 3:1 and neat devices with the decay of 15 %, 37 % and 71 % respectively. Additionally, a better recovery of electrical characteristics was observed in blend devices with larger polymer fractions from the deteriorating effects of gate bias stress.
2 citations
Cites background from "Study of electrical performance and..."
...The normalized drain current decay [17] was found to be least for 1:3 blend devices with 8....
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Dissertation•
07 Nov 2016
1 citations
Cites methods from "Study of electrical performance and..."
...According to this method, the on-state resistance RON is extracted as VDS approaches 0 V using the following expression [21]:...
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...First, the on-current RON as VDS approaches 0 V is extracted according to equation (3) (see chapter 1) and that is reproduced below [21, 107, 108]:...
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01 Apr 2019
TL;DR: In this paper, a bottom gate top contact organic field effect transistors with hybrid gate dielectric and TIPS-Pentacene:PS blend as active layer on PowerCoat™ HD 230 paper substrate is reported.
Abstract: We report on the fabrication of bottom gate top contact organic field effect transistors with hybrid gate dielectric and TIPS-Pentacene:PS blend as active layer on PowerCoat™ HD 230 paper substrate. The hybrid dielectric layer leads the devices operated at relatively low voltage of −10 V with avg. and maximum field effect mobility of $0.52(\pm 0.16)$ and 0.78 cm2 V−1 S−1 respectively, with near zero threshold voltage and on-off current ratio approaching ~104. The devices have shown excellent operational stability when tested with DC bias stress of $\mathrm{V}_{\mathrm{DS}}=\mathrm{V}_{\mathrm{GS}}=-10\ \mathrm{V}$ for 1 h and minuscule changes in electrical characteristics were observed with continuous multiple transfer cycle scans. In addition, we have demonstrated a resistive load inverter circuit with varying the load resistance with these paper OFETs.
1 citations
11 Dec 2022
TL;DR: In this article , a bi-layer combination of high-k/low-k gate dielectric consisting of polyvinyl alcohol (PVA) and poly (4-vinylphenol-co-methyl methacrylate) (PVP-Co-PMMA) polymers was explored to fabricate high performance flexible organic transistors.
Abstract: In this paper, a bi-layer combination of high-k/low-k gate dielectric consisting of poly (vinyl alcohol) (PVA) and poly (4-vinylphenol-co-methyl methacrylate) (PVP-Co-PMMA) polymers was explored to fabricate high performance flexible organic transistors. Solution processed TIPS-Pentacene: polystyrene (PS) was used to demonstrate p-channel transistors with excellent electrical characteristics. These devices exhibited average and maximum field-effect mobility (μ) values of ~0.2 (±0.1) cm^2/Vs and ~0.5 cm^2/V s in the saturation regime with high current (Ion/Ioff) ratio of ~10^4 at an operating voltage of -8 V, with negligible hysteresis in transfer curves. Moreover, excellent repeatability in electrical characteristics with high cyclic and bias stress stability were also achieved. These findings suggest that this unique bi-layer gate dielectric combination can act as an excellent alternative for solution processed organic transistors.
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TL;DR: A highly soluble and printable n-channel polymer exhibiting unprecedented OTFT characteristics under ambient conditions in combination with Au contacts and various polymeric dielectrics is reported and all-printed polymeric complementary inverters have been demonstrated.
Abstract: Printed electronics is a revolutionary technology aimed at unconventional electronic device manufacture on plastic foils, and will probably rely on polymeric semiconductors for organic thin-film transistor (OTFT) fabrication. In addition to having excellent charge-transport characteristics in ambient conditions, such materials must meet other key requirements, such as chemical stability, large solubility in common solvents, and inexpensive solution and/or low-temperature processing. Furthermore, compatibility of both p-channel (hole-transporting) and n-channel (electron-transporting) semiconductors with a single combination of gate dielectric and contact materials is highly desirable to enable powerful complementary circuit technologies, where p- and n-channel OTFTs operate in concert. Polymeric complementary circuits operating in ambient conditions are currently difficult to realize: although excellent p-channel polymers are widely available, the achievement of high-performance n-channel polymers is more challenging. Here we report a highly soluble ( approximately 60 g l(-1)) and printable n-channel polymer exhibiting unprecedented OTFT characteristics (electron mobilities up to approximately 0.45-0.85 cm(2) V(-1) s(-1)) under ambient conditions in combination with Au contacts and various polymeric dielectrics. Several top-gate OTFTs on plastic substrates were fabricated with the semiconductor-dielectric layers deposited by spin-coating as well as by gravure, flexographic and inkjet printing, demonstrating great processing versatility. Finally, all-printed polymeric complementary inverters (with gain 25-65) have been demonstrated.
2,769 citations
TL;DR: In this paper, the performance of organic field effect transistors (OFETs) is examined in terms of field effect mobility and on-off current ratio, and the most prominent fabrication techniques are described.
Abstract: Organic field-effect transistors (OFETs) were first described in 1987. Their characteristics have undergone spectacular improvements during the last two or three years. At the same time, several models have been developed to rationalize their operating mode. In this review, we examine the performance of OFETs as revealed by recently published data, mainly in terms of field-effect mobility and on–off current ratio. We compare the various compounds that have been used as the active component, and describe the most prominent fabrication techniques. Finally, we analyze the charge transport mechanisms in organic solids, and the resulting models of OFETs.
2,380 citations
TL;DR: It is demonstrated that the use of an appropriate hydroxyl-free gate dielectric—such as a divinyltetramethylsiloxane-bis(benzocyclobutene) derivative (BCB; ref. 6)—can yield n-channel FET conduction in most conjugated polymers, revealing that electrons are considerably more mobile in these materials than previously thought.
Abstract: Organic semiconductors have been the subject of active research for over a decade now, with applications emerging in light-emitting displays and printable electronic circuits. One characteristic feature of these materials is the strong trapping of electrons but not holes1: organic field-effect transistors (FETs) typically show p-type, but not n-type, conduction even with the appropriate low-work-function electrodes, except for a few special high-electron-affinity2,3,4 or low-bandgap5 organic semiconductors. Here we demonstrate that the use of an appropriate hydroxyl-free gate dielectric—such as a divinyltetramethylsiloxane-bis(benzocyclobutene) derivative (BCB; ref. 6)—can yield n-channel FET conduction in most conjugated polymers. The FET electron mobilities thus obtained reveal that electrons are considerably more mobile in these materials than previously thought. Electron mobilities of the order of 10-3 to 10-2 cm2 V-1 s-1 have been measured in a number of polyfluorene copolymers and in a dialkyl-substituted poly(p-phenylenevinylene), all in the unaligned state. We further show that the reason why n-type behaviour has previously been so elusive is the trapping of electrons at the semiconductor–dielectric interface by hydroxyl groups, present in the form of silanols in the case of the commonly used SiO2 dielectric. These findings should therefore open up new opportunities for organic complementary metal-oxide semiconductor (CMOS) circuits, in which both p-type and n-type behaviours are harnessed.
2,191 citations
TL;DR: New semiconducting liquid-crystalline thieno[3,2-b ]thiophene polymers are reported on, the enhancement in charge-carrier mobility achieved through highly organized morphology from processing in the mesophase, and the effects of exposure to both ambient and low-humidity air on the performance of transistor devices.
Abstract: Organic semiconductors that can be fabricated by simple processing techniques and possess excellent electrical performance, are key requirements in the progress of organic electronics. Both high semiconductor charge-carrier mobility, optimized through understanding and control of the semiconductor microstructure, and stability of the semiconductor to ambient electrochemical oxidative processes are required. We report on new semiconducting liquid-crystalline thieno[3,2-b ]thiophene polymers, the enhancement in charge-carrier mobility achieved through highly organized morphology from processing in the mesophase, and the effects of exposure to both ambient and low-humidity air on the performance of transistor devices. Relatively large crystalline domain sizes on the length scale of lithographically accessible channel lengths (∼200 nm) were exhibited in thin films, thus offering the potential for fabrication of single-crystal polymer transistors. Good transistor stability under static storage and operation in a low-humidity air environment was demonstrated, with charge-carrier field-effect mobilities of 0.2–0.6 cm2 V−1 s−1 achieved under nitrogen.
2,011 citations
TL;DR: In this article, an electrophoretic ink based on the microencapsulation of an electrophic dispersion was used to solve the lifetime issues and allow the fabrication of a bistable electronic display solely by means of printing.
Abstract: It has for many years been an ambition of researchers in display media to create a flexible low-cost system that is the electronic analogue of paper. In this context, microparticle-based displays1,2,3,4,5 have long intrigued researchers. Switchable contrast in such displays is achieved by the electromigration of highly scattering or absorbing microparticles (in the size range 0.1–5 μm), quite distinct from the molecular-scale properties that govern the behaviour of the more familiar liquid-crystal displays6. Microparticle-based displays possess intrinsic bistability, exhibit extremely low power d.c. field addressing and have demonstrated high contrast and reflectivity. These features, combined with a near-lambertian viewing characteristic, result in an ‘ink on paper’ look7. But such displays have to date suffered from short lifetimes and difficulty in manufacture. Here we report the synthesis of an electrophoretic ink based on the microencapsulation of an electrophoretic dispersion8. The use of a microencapsulated electrophoretic medium solves the lifetime issues and permits the fabrication of a bistable electronic display solely by means of printing. This system may satisfy the practical requirements of electronic paper.
1,210 citations