Effect of the phenyl ring orientation in the polystyrene buffer layer on the performance of pentacene thin-film transistors (original) (raw)
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Pentacene thin film transistors fabricated on plastic substrates
Synthetic Metals, 2003
In this study, Organic thin film transistors (OTFT) was fabricated on polyethylene naphthalate (PEN) substrate employing Au as source, drain, and gate electrodes. Double-layer of organic dielectrics, thermal curable acrylate polymer (JSS-362) and inorganic dielectrics, aluminum oxide (Al 2 O 3 ) was used as gate dielectrics. The polymeric layer on PEN substrate showed smoother surface than that of PEN substrate. Little surface damage of JSS-362 layer was achieved by using off-axis sputtering apparatus during the inorganic dielectrics fabrication. From the electrical measurements, typical I-V characteristics of the thin film transistor (TFT) device were observed. The field-effect mobility µ was calculated to be 1.4 × 10 −2 cm 2 V −1 s −1 , while the threshold voltage V T was about −7 V. The on/off ratio was above 10 3 when V G was scanned from −50 to +30 V.
Solution processed high-performance organic thin film transistors
Organic Field-Effect Transistors V, 2006
In this study, we achieved high performance organic small molecule transistors by using roll-to-roll slot die coating technique and polymer dielectric layers. By carefully controlling the coating conditions, highly ordered single crystalline thin films could be achieved. Hence, the organic thin film transistor (OTFT) device exhibited an average mobility of 4.2 cm 2 V-1 s-1 and maximum mobility of 6.5 cm 2 V-1 s-1 based on polystyrene (PS) dielectric layer in the ambient air condition, which is among the best values for TIPS-pentacene based devices. The thin film morphology, crystallinity, and optical properties were studied in details. A complementary inverter based on p-type TIPS-pentacene and n-type 6,13-Dicyano pentacene-2,3:9,10-bis(dicarboximide) (PDI-CN) with a high voltage gain of 54 was achieved. Finally, the flexible devices
Pentacene organic thin-film transistors for circuit and display applications
IEEE Transactions on Electron Devices, 1999
We have fabricated organic thin-film transistors (TFT's) using the small-molecule polycyclic aromatic hydrocarbon pentacene as the active material. Devices were fabricated on glass substrates using low-temperature ion-beam deposited silicon dioxide as the gate dielectric, ion-beam deposited palladium for the source and drain contacts, and vacuum-evaporated pentacene to form the active layer. Excellent electrical characteristics were obtained, including carrier mobility as large as 0.6 cm 2 /V-s, on/off current ratio as large as 10 8 , and subthreshold slope as low as 0.7 V/dec, all record values for organic transistors fabricated on nonsingle-crystal substrates. Jonathan A. Nichols received the B.A. degree in physics from Edinboro University, Edinboro, PA, and the B.S. degree in materials science and engineering from the Pennsylvania State University, University Park, in 1998, where he is currently pursuing the M.S. degree in materials engineering at the Center for Thin Film Devices. His research focuses on the processing and material characterization of organic thin-film transistors.
Enhanced field-effect mobility in pentacene based organic thin-film transistors on polyacrylates
Journal of Applied Physics, 2009
We reported on organic thin-film transistors (OTFTs) with high dielectric constant polymer, poly(2,2,2-trifluoroethyl methacrylate) (PTFMA), as the gate dielectric. In top-contact OTFTs, the field-effect mobility was enhanced by applying a dielectric buffer layer poly(α-methylstyrene) to the bare PTFMA. After improving interfacial affinity within the active layer/dielectrics, deposited pentacene grain size and device performance were enhanced dramatically. The corresponding mobility, threshold voltage, and on/off current ratio were 0.70 cm2 V−1 s−1, −10.5 V, and 5.4×105, respectively. The moderately improved interface also suppressed the hole-trapping effect, which led to less hysteresis and minimized threshold voltage shift.
The European Physical Journal Applied Physics, 2012
The organic thin-film transistors (OTFTs) incorporating pentacene/SU-8 interface were fabricated and characterized. SU-8, a reliable epoxy-based photoresist, is tested as a potential highly-stable polymeric gate dielectric for OTFTs. The fabricated devices showed promising electrical performance with on-off ratio up to 10 7 and field-effect mobility up to 0.56 cm 2 /V s. Several device characteristics are further analyzed. There existed a leakage current path due to the uncontrolled pentacene coverage and we revealed that precise alignment of the evaporation mask of pentacene is critical for eliminating this problem. Pentacene grain formation largely depended on the growth condition on the SU-8 surface and small-grain films offered outstanding performance possibly owing to enhanced inter-domain connections. Natural degradation of the OTFTs is also discussed in terms of environmental stability and the pentacene/SU-8 transistor operated with noticeable air stability under ambient conditions.
We report on the surface-induced molecular order and the optical anisotropy of a pentacene thin film on a photo-aligned polymeric gate insulator layer. Since a pentacene molecule has a rodlike shape, the induced orientational order of the pentacene molecules is expected on an alignment layer for liquid crystal molecules. The photo-aligned polymer insulator, exposed to a linearly polarized ultraviolet light, has a high cross-linked density and thus induces the structural order of the pentacene molecules. The pentacene thin film deposited on the photo-aligned polymeric insulator is found to show the optical anisotropy. The organic thin film transistor on the photo-aligned insulator exhibits good electrical properties.
Journal of Non-crystalline Solids, 2004
Pentacene thin-film transistors using polymethyl methacrylate as a gate dielectric have been fabricated. A bottom gate, inverted staggered structure was selected to study the influence of the dielectric on the device performance. Crystalline silicon wafers and polyethylenenaphtalate polymer foils were used as substrates. Pentacene thin-films were deposited by thermal evaporation in a highvacuum system. The maximum process temperature was 170°C, corresponding to the baking of polymethyl methacrylate. These devices showed satisfactory p-type electrical characteristics with on/off ratios exceeding 10 3 for V GS ranging from )30 to 30 V. The field-effect mobility and threshold voltage were around 0.01 cm 2 V À1 s À1 and )14 V, respectively. The polymethyl methacrylate dielectric also seems to provide some advantages of the so-called self-assembling monolayers.
Global Journal of Research In Engineering, 2019
In this paper, we model the characteristics of top and bottom gate configurations of organic thin film transistors (OTFTs) including top gate top contact (TGTC), top gate bottom contact (TGBC), bottom gate top contact (BGTC) , bottom gate bottom contact (BGBC). The path of charge carriers changes in different geometries which possess difference in the electrical behaivour of the devices. The performances of bottom and top gate pentacene based OTFT devices have been analyzed and their performance parameters like mobility, threshold voltage, sub threshold slope, trans conductance, on off ratio have been extracted and compared. Keywords: organic thin film transistors (OTFTS), numerical simulation, pentacene, top gate top contact (TGTC), top gate bottom contact (TGBC), bottom gate top contact (BGTC) and bottom gate bottom contact (BGBC).
Organic Thin Film Transistor Architecture, Parameters and their Applications
Organic Thin Film Transistors (OTFTs) are promising devices for future development of variety of low-cost and large-area electronics applications such as flexible displays. This paper analyzes the performance of OTFT made of several organic semi conducting and insulating materials and further discusses their applications. Analysis of previous research work demonstrates that the mobility in OTFT decreases when the product of semi conducting film thickness and gate capacitance per unit area increases. The decrease is specified by a power law function with parameters for several organic semiconductors. OTFT characteristics have undergone spectacular improvements during the last few years. This paper explores the effect of variation of channel length from 40 nm to 20 nm on drain current for pentacene bottom contact structure. Variations in these quantities maps to variations in the electrical behaviour of devices. It has been found that drain current increases due to decrease in length of organic thin film conducting channel. It reviews recent progress in parameter properties for device designs and applications related to OTFTs. The performance of OTFTs is evaluated in terms of mobility, on/off current ratio, threshold voltage and sub threshold slope. This paper thoroughly discusses the overall performance and applications of OTFTs in various fields.