共查询到20条相似文献,搜索用时 31 毫秒
1.
Manoj Parameswaran Ganapathy Balaji Tan Mein Jin Chellappan Vijila Sajini Vadukumpully Zhu Furong Suresh Valiyaveettil 《Organic Electronics》2009,10(8):1534-1540
Charge mobility characteristics of a newly synthesised 2,6-bis[2-(9,9-dihexyl-9H-fluorene)]-N-(4-hexylphenyl)-dithieno[3,2-b:2′,3′-d]pyrrole oligomer (DTP-FLU) was studied as a function of electric field and temperature using time-of-flight photoconductivity measurement. It is found that the DTP-FLU oligomer is a hole transporting material with a hole mobility of 7.7 × 10?6 cm2/Vs at an applied electric field of 2.9 × 105 V/cm at 298 K. The dependence of hole mobility with applied electric field and temperature is studied in detail by analyzing the experimental results using the Bassler’s Gaussian disorder model and Correlated disorder model. The energetic disorder parameter (σ) = 100 meV, mobility pre-factor (μ∞) = 6.1 × 10?4 cm2/Vs and positional disorder parameter (Σ) = 2.4 were extracted using Gaussian disorder model. The film morphology and photophysical properties of this new oligomer are also studied in detail. 相似文献
2.
《Organic Electronics》2014,15(7):1521-1530
Novel two-dimensional π-conjugated molecules, i.e., 5′,5″′-((9,10-bis((4-hexylphenyl)ethynyl)anthracene-2,6-diyl)bis(ethyne-2,1-diyl))bis(5-hexyl-2,2′-bithiophene) (2,6-HBT) and 5′,5″′-((2,6-bis((4-hexylphenyl)ethynyl)anthracene-9,10-diyl)bis(ethyne-2,1-diyl))bis(5-hexyl-2,2′-bithiophene) (9,10-THB) were successfully synthesized and utilized as highly soluble p-type organic semiconductors for organic thin film transistors (TFTs) and solar cells. From the TFTs, the high hole mobility of the pristine film of 9,10-THB was measured to be 0.07 cm2 V−1 s−1 (Ion/off = 106–107), which is mainly attributed to slip-stacked charge-transport behavior in J-aggregation-induced crystallites. Further, a solution-processed solar cell made of 9,10-THB and PC61BM exhibited very promising and reproducible power conversion efficiencies of 3.30% and 2.53% with composition 1:1 and 1:2 w/w ratio, respectively. 相似文献
3.
《Organic Electronics》2007,8(1):8-13
The charge transport properties in a novel electroluminescent poly{[2-(4′,5′-bis(3″-methylbutoxy)-2′-p-methoxy-phenyl)phenyl-1,4-phenylene vinylene]-co-(9,9-dioctyl-2,7-fluorenylene vinylene)} (BPPPV-PF) have been studied using a time-of-flight (TOF) photoconductivity technique. The TOF transients for holes were recorded over a range of temperatures (207–300 K) and electric fields (1.5 × 105–6.1 × 105 V/cm). The hole transport in this polymer was weakly dispersive in nature with a mobility at 300 K of 5 × 10−5 cm2/V s at 2.5 × 105 V/cm. This increased to 8.4 × 10−5 cm2/V s at 6.1 × 105 V/cm. The temperature and field dependence of charge mobility has been analyzed using the disorder formalisms (Bässler’s Gaussian disorder model (GDM) and correlated disorder model (CDM)). The fit with Gaussian disorder (GDM) model yielded the mobility pre-factor μ∞ = 1.2 × 10−3 cm2/V s, energetic disorder parameter σ = 82 meV and positional disorder parameter Σ = 1.73. The average inter-site separation (a = 7 Å) and the charge localization length (L = 3.6 Å) was estimated by assuming the CDM type charge transport. The microscopic charge transport parameters derived for this polymer are almost identical to the reported values for fully conjugated polymers with high chemical purity. The results presented indicate that the charge transport parameters can be controlled and optimized for organic optoelectronic applications. 相似文献
4.
Jae-Hong Kwon Sang-Il Shin Jinnil Choi Myung-Ho Chung Tae-Yeon Oh Kyung-Hwan Kim Min Ju Cho Kyu Nam Kim Dong Hoon Choi Byeong-Kwon Ju 《Organic Electronics》2009,10(4):729-734
The effects of the physical channel width on the characteristics of organic thin film transistors (OTFTs), made with 6,13-bis(triisopropyl-silylethynyl)-pentacene (TIPS-pentacene) embedded into poly-triarylamine (PTAA, hole conductor within an active channel), have been examined in this paper. The devices are estimated by measuring the drain-source current (IDS) for different contact metals such as Au and Ag, at fixed gate and drain voltages. The results show that the threshold voltage (VT) and IDS increase with increasing channel width. Furthermore, it has been observed that the field effect mobility is dependent on VT, which is influenced by the channel width. The OTFTs, produced using Au and Ag contacts, exhibited the highest values of mobility in the saturation regime, namely 5.44 × 10?2 and 1.33 × 10?2 cm2/Vs, respectively. 相似文献
5.
Chu-Chen Chueh Tomoya Higashihara Jung-Hsun Tsai Mitsuru Ueda Wen-Chang Chen 《Organic Electronics》2009,10(8):1541-1548
The electronic properties, morphology and optoelectronic device characteristics of conjugated diblock copolythiophene, poly(3-hexylthiophene)-block -poly(3-phenoxymethylthiophene) (P3HT-b-P3PT), are firstly reported. The polymer properties and structures were explored through different solvent mixtures of chloroform (CHCl3), dichlorobenzene (DCB), and CHCl3:DCB (1:1 ratio). The absorption maximum (λmax) of P3HT-b-P3PT prepared from DCB was around 554 nm with a shoulder peak indicative for the highly crystalline structure around 604 nm while that from CHCl3 was 516 nm without the clear shoulder peak. The field-effect hole mobility of P3HT-b-P3PT increased from ~6.0 × 10?3, ~8.0 × 10?3 to ~2.0 × 10?2 cm2 V?1 s?1 as the DCB content in the solvent mixture enhanced. The AFM images suggested that the highly volatile CHCl3 processing solvent led to the amorphous structure, on the other hand, less volatile DCB resulted in the largely crystalline structure of the P3HT-b-P3PT. Such difference on the polymer structure and hole mobility led to the varied power conversion efficiency (PCE) of the photovoltaic cells fabricated from the blend of P3HT-b-P3PT/[6,6]-phenyl-C61-butyric acid methyl ester (PCBM) (1:1, w/w): 1.88 (CHCl3), 2.13 (CHCl3:DCB (1:1)), and 2.60% (DCB). The PCBM blend ratio also significantly affected the surface structure and the solar cell performance. The PCE of polymer/PCBM could be improved to 2.80% while the ratio of polymer to PCBM went to 1:0.7. The present study suggested that the surface structures and optoelectronic device characteristics of conjugated diblock copolymers could be easily manipulated by the processing solvent, the block segment characteristic, and blend composition. 相似文献
6.
Slice-like organic single crystals of 1,4-bis(2-cyano-2-phenylethenyl)benzene (BCPEB) are grown by the physical vapor transport (PVT) method, and exhibit a very high photoluminescence quantum efficiency (ΦPL) of 75%. The ambipolar behavior of BCPEB single crystals are confirmed using the time of flight technique. The high efficiency and balanced (μh = 0.059 cm2/Vs and μe = 0.070 cm2/Vs) carriers’ mobility imply that the BCPEB single crystal is a promising light-emitting layer in the diodes structure. Intense green electroluminescence (EL) from a diode has been successfully demonstrated at an applied electric field of 2 × 105 V/cm. 相似文献
7.
《Organic Electronics》2014,15(8):1884-1889
Solution-processed n-type organic field effect transistors (OFETs) are in need of proper metal contact for improving injection and mobility, as well as balanced hole mobility for building logic circuit units. We address the two distinct problems by a simple technique of transfer-printing. Transfer-printed Au contacts on a terrylene-based semiconductor (TDI) significantly reduced the inverse subthreshold slope by 5.6 V/dec and enhanced the linear mobility by over 5 times compared to evaporated Au contacts. Hence, devices with a high-work-function metal (Au) are comparable with those with low-work-function metals (Al and Ca), indicating a fundamental advantage of transfer-printed electrodes in electron injection. We also transfer-printed a poly(3-hexylthiophene) (P3HT) layer onto TDI to construct a double-channel ambipolar transistor by a solution process for the first time. The transistor exhibits balanced hole and electron mobility (3.0 × 10−3 and 2.8 × 10−3 cm2 V−1 s−1) even in a coplanar structure with symmetric Au electrodes. The technique is especially useful for reaching intrinsic mobility of new materials, and enables significant enlargement of the material tanks for solution-processed functional heterojunction OFETs. 相似文献
8.
《Solid-state electronics》2006,50(9-10):1515-1521
Al0.26Ga0.74N/AlN/GaN high-electron-mobility transistor (HEMT) structures with AlN interfacial layers of various thicknesses were grown on 100-mm-diameter sapphire substrates by metalorganic vapor phase epitaxy, and their structural and electrical properties were characterized. A sample with an optimum AlN layer thickness of 1.0 nm showed a highly enhanced Hall mobility (μHall) of 1770 cm2/Vs with a low sheet resistance (ρs) of 365 Ω/sq. (2DEG density ns = 1.0 × 1013/cm2) at room temperature compared with those of a sample without the AlN interfacial layer (μHall = 1287 cm2/Vs, ρs = 539 Ω/sq., and ns = 0.9 × 1013/cm2). Electron transport properties in AlGaN/AlN/GaN structures were theoretically studied, and the calculated results indicated that the insertion of an AlN layer into the AlGaN/GaN heterointerface can significantly enhance the 2DEG mobility due to the reduction of alloy disorder scattering. HEMTs were successfully fabricated and characterized. It was confirmed that AlGaN/AlN/GaN HEMTs with the optimum AlN layer thickness show superior DC properties compared with conventional AlGaN/GaN HEMTs. 相似文献
9.
Self-assembled GaAs nanowires were grown by molecular beam epitaxy (MBE) on un-pretreated Si(111) substrates under different As4/Ga flux ratios (V/III ratios). It has been found that the fraction of vertical wires would be nearly 100% when the As4/Ga ratio arrives 90. The transmission electron microscopy (TEM) and micro-photoluminescence (PL) spectra results have indicated that the GaAs nanowires grown under a larger V/III ratio (90) have a pure ZB structure. Field-effect transistors (FET) based on single nanowire were fabricated with GaAs nanowires grown under the larger V/III ratio (90). The characteristics of the FET reveal a hole concentration of 3.919×1017 cm−3 and a hole mobility of 0.417 cm2 V−1s−1. Photodetectors based on single nanowire and multiple nanowires structure with a metal-semiconductor-metal (MSM) electrode configuration have been proposed and demonstrated. All the photodetectors operating at room temperature exhibit good photoconductive performance, excellent stability, reproducibility and superior peak responsivity (87.67 A/W under 5 V for single nanowire photodetector). 相似文献
10.
Effective mobility in amorphous organic transistors: Influence of the width of the density of states
《Organic Electronics》2014,15(1):35-39
The temperature dependence of poly(3-hexylthiophene-2,5-diyl) (P3HT)/polystyrene (PS) blend organic transistor current/voltage (I–V) characteristics has been experimentally and theoretically studied. The planar transistors, realized by drop casting the P3HT/PS ink, exhibit high mobilities (over 5 × 10−3 cm2 V−1 s−1) and good overall characteristics. A transistor model accounting for transport mechanisms in disordered organic materials was used to fit the measured characteristics. Using a single set of parameters, the measured effective mobility versus gate bias, either increasing or decreasing with the gate bias depending on temperature, is well reproduced over a wide temperature range (130–343 K). A Gaussian density of states width of 0.045 eV was determined for this P3HT/PS blend. The transistor I–V characteristics are very well described considering disordered material properties within a self-consistent transistor model. 相似文献
11.
Akshaya K. Palai Hyejin Cho Sungwoo Cho Tae Joo Shin Soonmin Jang Seung-Un Park Seungmoon Pyo 《Organic Electronics》2013,14(5):1396-1406
We report the synthesis, characterization and behavior in field-effect transistors of non-functionalized soluble diketopyrrolopyrrole (DPP) core with only a solubilizing alkyl chain (i.e. –C16H33 or –C18H37) as the simplest p-channel semiconductor. The characteristics were evaluated by UV–vis and fluorescence spectroscopy, X-ray diffraction, cyclic voltammetry (CV), thermal analysis, atomic force microscopy (AFM) and density functional theory (DFT) calculation. For top-contact field-effect transistors, two types of active layers were prepared either by a solution process (as a 1D-microwire) or thermal vacuum deposition (as a thin-film) on a cross-linked poly(4-vinylphenol) gate dielectric. All the devices showed typical p-channel behavior with dominant hole transports. The device made with 1D-microwiress of DPP-R18 showed field-effect mobility in the saturation region of 1.42 × 10?2 cm2/V s with ION/IOFF of 1.82 × 103. These findings suggest that the non-functionalized soluble DPP core itself without any further functionalization could also be used as a p-channel semiconductor for low-cost organic electronic devices. 相似文献
12.
Shungo Kojima Toshihiro Okamoto Kazumoto Miwa Hiroyasu Sato Jun Takeya Yutaka Matsuo 《Organic Electronics》2013,14(2):437-444
Benzopyrazine-fused tetracene (TBPy) and its disulfide (TBPyS) bearing alkoxy groups (OCH3, OC8H17) were designed and synthesized to obtain π-expanded tetracene derivatives. These derivatives are featured with long-wavelength light absorption property (λonset: up to 820 nm), photooxidative stability (half-lives (τ1/2): 11 times longer than tetracene), and solubility for solution process. The methoxy compounds (TBPy-C1 and TBPyS-C1) were used for single-crystal X-ray crystallographic analysis and single-crystal organic field-effect transistor (OFET) devices showing relationship between packing structures and hole mobilities. The octyloxy compounds (TBPy-C8 and TBPyS-C8) were investigated on solution-processed thin-film formation and hole transport property in thin-film OFET devices. Crystalline mesophase of TBPy-C8 and TBPyS-C8 was characterized by differential scanning calorimetry analysis showing endothermic peaks at 98 and 198 °C on its second heating process and exothermic peaks at 177 and 76 °C on its second cooling process for TBPyS-C8, and played crucial roles in thin-films formation. Hole mobility of 1.7 × 10?2 cm2/V s (with Vth = ?30 V and ION/IOFF = 104) was obtained for the thin-film OFET device of TBPyS-C8. 相似文献
13.
Donor–acceptor (D–A) type conjugated polymers have been developed to absorb longer wavelength light in polymer solar cells (PSCs) and to achieve a high charge carrier mobility in organic field-effect transistors (OFETs). PDTDP, containing dithienothiophene (DTT) as the electron donor and diketopyrrolopyrrole (DPP) as the electron acceptor, was synthesized by stille polycondensation in order to achieve the advantages of D–A type conjugated polymers. The polymer showed optical band gaps of 1.44 and 1.42 eV in solution and in film, respectively, and a HOMO level of 5.09 eV. PDTDP and PC71BM blends with 1,8-diiodooctane (DIO) exhibited improved performance in PSCs with a power conversion efficiency (PCE) of 4.45% under AM 1.5G irradiation. By investigating transmission electron microscopy (TEM), atomic force microscopy (AFM), and the light intensity dependence of JSC and VOC, we conclude that DIO acts as a processing additive that helps to form a nanoscale phase separation between donor and acceptor, resulting in an enhancement of μh and μe, which affects the JSC, EQE, and PCE of PSCs. The charge carrier mobilities of PDTDP in OFETs were also investigated at various annealing temperatures and the polymer exhibited the highest hole and electron mobilities of 2.53 cm2 V−1 s−1 at 250 °C and 0.36 cm2 V−1 s−1 at 310 °C, respectively. XRD and AFM results demonstrated that the thermal annealing temperature had a critical effect on the changes in the crystallinity and morphology of the polymer. The low-voltage device was fabricated using high-k dielectric, P(VDF-TrFE) and P(VDF-TrFE-CTFE), and the carrier mobility of PDTDP was reached 0.1 cm2 V−1 s−1 at Vd = −5 V. PDTDP complementary inverters were fabricated, and the high ambipolar characteristics of the polymer resulted in an output voltage gain of more than 25. 相似文献
14.
Tsung-Cheng Tsai Wen-Yi Hung Liang-Chen Chi Ken-Tsung Wong Cheng-Chih Hsieh Pi-Tai Chou 《Organic Electronics》2009,10(1):158-162
A novel blue emitter, In2Bt, featured with a rigid and coplanar distyryl-p-phenylene backbone flattened by two different bridging atoms (i.e. carbon and sulfur) exhibits high thermal and morphological stability (Tg ~ 192 °C) and ambipolar charge carrier mobilities in the range of 10?4 ~ 10?5 cm2 V?1 s?1. OLED device: ITO/PEDOT:PSS (300 Å)/α-NPD (200 Å)/TCTA (100 Å)/In2Bt (200 Å)/TPBI (500 Å)/LiF (5 Å)/Al (1500 Å) utilized In2Bt as an emitter gave a maximum brightness as high as 8000 cd m?2 (12 V) and saturated-blue emission with CIE chromaticity coordinates of (0.16, 0.08), which is very close to the National Television Standards Committee (NTSC) standard blue gives an enlarged palette of colors for color displays. 相似文献
15.
《Solid-state electronics》2006,50(7-8):1175-1177
In0.75Ga0.25As channel layers with a record mobility exceeding 12,000 cm2/Vs for use in high-κ dielectric NMOSFETs have been fabricated. The device structures which have been grown by molecular beam epitaxy on 3″ semi-insulating InP substrate comprise a 10 nm strained In0.75Ga0.25As channel layer and a high-κ oxide based dielectric layer (κ ≅ 20). Electron mobilities of 12,033 and 7,042 cm2/Vs have been measured for sheet carrier concentrations ns of 2.5 × 1012 and 6 × 1012 cm−2, respectively. 相似文献
16.
A series of simple structures is investigated for realization of the highly efficient green phosphorescent organic light emitting diodes with relatively low voltage operation. All the devices were fabricated with mixed host system by using 1,1-bis[(di-4-tolylamino)phenyl]cyclohexane (TAPC) and 1,3,5-tri(p-pyrid-3-yl-phenyl)benzene (TpPyPB) which were known to be hole and electron type host materials due to their great hole and electron mobilities [μh(TAPC): 1 × 10?2 cm2/V s and μe(TpPyPB): 7.9 × 10?3 cm2/V s] [1]. The optimized device with thin TAPC (5–10 nm) as an anode buffer layer showed relatively high current and power efficiency with low roll-off characteristic up to 10,000 cd/m2. The performances of the devices; with buffer layer were compared to those of simple devices with single layer and three layers. Very interestingly, the double layer device with TAPC buffer layer showed better current and power efficiency behavior compared to that of three layer device with both hole and electron buffer layers (TAPC, TpPyPB, respectively). 相似文献
17.
Zhi Qiang Gao Ping Fan Xia Pik Kwan Lo Bao Xiu Mi Hoi Lam Tam Man Shing Wong Kok Wai Cheah Chin H. Chen 《Organic Electronics》2009,10(4):666-673
Two novel p-phenylenediamine-substituted fluorenes have been designed and synthesized. Their applications as hole injection materials in organic electroluminescent devices were investigated. These materials show a high glass transition temperature and a good hole-transporting ability. It has been demonstrated that the 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4-TCNQ) doped p-phenylene-diamine-substituted fluorenes, in which F4-TCNQ acts as p-type dopant, are highly conducting with a good hole-transporting property. The organic light emitting devices (OLEDs) utilizing these F4-TCNQ-doped materials as a hole injection layer were fabricated and investigated. The pure Alq3-based OLED device shows a current efficiency of 5.2 cd/A at the current density of 20 mA/cm2 and the operation lifetime is 1500 h with driving voltage increasing only about 0.7 mV/h. The device performance and stability of this hole injection material meet the benchmarks for the commercial requirements for OLED materials. 相似文献
18.
James S. Swensen Liang Wang James E. Rainbolt Phillip K. Koech Evgueni Polikarpov Daniel J. Gaspar Asanga B. Padmaperuma 《Organic Electronics》2012,13(12):3085-3090
We report a solution processed, p-doped film consisting of the organic materials 4,4′,4″-tris(3-methylphenylphenylamino)triphenylamine (MTDATA) as the electron donor and 2-(3-(adamantan-1-yl)propyl)-3,5,6-trifluorotetracyanoquinodimethane (F3TCNQ-Adl) as the electron acceptor. UV–vis–NIR absorption spectra identified the presence of a charge transfer complex between the donor and acceptor in the doped films. Field-effect transistors were used to characterize charge transport properties of the films, yielding mobility values. Upon doping, mobility increased and then slightly decreased while carrier concentration increased by two orders of magnitude, which in tandem leads to conductivity increasing from 4 × 10?10 S/cm when undoped to 2 × 10?7 S/cm at 30 mol% F3TCNQ-Adl. The hole density was calculated based on mobility values extracted from OFET data and conductivity values extracted from bulk I–V data for the MTDATA: x mol% F3TCNQ-Sdl films. These films were then shown to function as the hole injection/hole transport layer in a phosphorescent blue OLED. 相似文献
19.
Na2MnPO4F is synthesized by hydrothermal route at 453 K and the physical properties and photo-electrochemical characterizations are reported. The compound crystallizes in a monoclinic system (SG: P 21/n) with the lattice constants: a=13.7132 Å, b=5.3461 Å, c=13.7079 Å, β=119.97°. The UV–visible spectroscopy shows an indirect optical transition at 2.68 eV; a further direct transition occurs at 3.70 eV, due to the charge transfer O2−: 2p → Mn2+: eg. The thermal variation of the electrical conductivity is characteristic of a semiconducting behavior with activation energy of 39 meV and an electron mobility (µ318 K=5.56×10−4 cm2 V−1 s−1), thermally activated. The flat band potential (+0.47 VSCE) indicates that the valence band derives mainly from O2−: 2p orbital with a small admixture of F− character while the conduction band is made up of Mn2+: t2g orbital. The electrochemical impedance spectroscopy shows the contribution of both the bulk and grains boundaries. The photocatalytic performance of Na2MnPO4F for the degradation of Rhodamine B (RhB) is demonstrated on the basis of the energy diagram. 88% of the initial concentration is degraded under UV light and the oxidation follows a first order kinetic with a rate constant of 0.516 h−1. Neither adsorption nor photolysis is observed. The photoactivity results from the electron transition from the hybridized band (O2−, F−) to the Mn2+: eg orbital, occurring in the UV region. The catalyst was subjected to three successive photocatalytic cycles, thus proving its long term stability. 相似文献
20.
Emilie Bernard T. Ernst B. Guillaumot N. Vulliet X. Garros V. Maffini-Alvaro P. Coronel T. Skotnicki S. Deleonibus 《Solid-state electronics》2008,52(9):1297-1302
In this study, we integrate and compare the electrical performances of metal/high-K embedded gates in 3D multi-channel CMOSFETs (MCFETs) on SOI. The electrical characteristics of embedded gates obtained by filling cavities with TiN/HfO2, TiN/SiO2 or N+ poly-Si/SiO2 are compared to a planar reference. In particular, we investigate electron and hole mobility behaviours (300 K down to 20 K) in embedded and planar structures, the gate leakage current and the negative bias temperature instability (NBTI). Despite a lower mobility, TiN/HfO2 gate stack demonstrates the best ION/IOFF compromise and exhibits NBTI life time higher than 10 years up to 1.3 V. 相似文献