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1.
We present a combined charge transport and X-ray diffraction study of blends based on regioregular poly(3-hexylthiophene) (P3HT) and the polyfluorene co-polymer poly((9,9-dioctylfluorene)-2,7-diyl-alt-[4,7-bis(3-hexylthien-5-yl)-2,1,3-benzothiadiazole]-2′,2′′-diyl) (F8TBT) that are used in efficient all-polymer solar cells. Hole mobility is observed to increase by nearly two orders of magnitude from less than 10?7 cm2 V?1 s?1 for as spin-coated blends to 6 × 10?6 cm2 V?1 s?1 for blends annealed at 453 K at a field of 2.7 × 105 V/cm, but still significantly below the time-of-flight mobility of unblended P3HT of 1.7 × 10?4 cm2 V?1 s?1. The hole mobility of the blends also show a strong negative electric-field dependence, compared with a relatively flat electric-field dependence of unblended P3HT, suggestive of increased spatial disorder in the blends. X-ray diffraction measurements reveal that P3HT/F8TBT blends show a phase separation of the two components with a crystalline part attributed to P3HT and an amorphous part attributed to F8TBT. In as-spun and mildly annealed blends, the measured d-values and relative intensities of the 100, 200 and 300 P3HT peaks are noticeably different to unblended P3HT indicating an incorporation of F8TBT in P3HT crystallites that distorts the crystal structure. At higher anneal temperatures the blend d-values approach that of unblended P3HT suggesting a well separated blend with pure P3HT crystallites. P3HT crystallite size in the blend is also observed to increase with annealing from 3.3 to 6.1 nm, however similar changes in crystallite size are observed in unblended P3HT films with annealing. The lower mobility of P3HT/F8TBT blends is attributed not only to increased P3HT structural disorder in the blend, but also due to the blend morphology (increased spatial disorder). Changes in hole mobility with annealing are interpreted in terms of the need to form percolation networks of P3HT crystallites within an F8TBT matrix, with a possible contribution due to the intercalation of F8TBT in P3HT crystallites acting as defects in the as-prepared state. 相似文献
2.
《Organic Electronics》2008,9(6):1136-1139
We have fabricated polymer solar cell devices based on poly(3-hexylthiophene):[6,6]-phenyl-C61-butyric acid methyl ester (P3HT:PCBM) and incorporating one-dimensional nanostructured acid-doped polyaniline nanotubes (a-PANINs) as an interfacial layer. The power conversion efficiency of an annealed device incorporating the a-PANIN layer reached 4.26% under AM 1.5 G (100 mW/cm2) illumination, an increase of ca. 26% relative to that of the annealed device lacking an a-PANIN interfacial layer. The incorporation of the a-PANINs in the solution-processed polymer solar cells was reproducible; the high conductivity, controlled tubular nanoscale morphologies, and mobility of the annealed a-PANIN layer led to efficient extraction of photogenerated holes to the buffer layer and suppression of exciton recombination, thereby improving the photovoltaic performance. 相似文献
3.
《Organic Electronics》2008,9(3):317-322
With the aim of enhancing the field-effect mobility of poly(3-hexylthiophene) (P3HT) field-effect transistors (FETs), we added functionalized multiwalled carbon nanotubes (CNTs) to the P3HT solution prior to film formation. The nanotubes were found to be homogeneously dispersed in the P3HT films because of their functional groups. We found that at the appropriate CNT concentration (up to 10 wt% CNT), the P3HT FETs have a high field-effect mobility of 0.04 cm2 V−1 s−1, which is an improvement by a factor of more than 10. This remarkable increase in the field-effect mobility over that of the pristine P3HT film is due to the high conductivity of the CNTs which act as conducting bridges between the crystalline regions of the P3HT film, and the reduction in the hole-injection barrier due to the low work function of CNTs, which results in more efficient carrier injection. 相似文献
4.
Room-temperature exposure of spin-coated poly(3-hexylthiophene) (P3HT) films to ortho-dichlorobenzene vapor increases the field-effect mobility of the P3HT organic thin-film transistors (OTFTs). The mobility increases moderately with unsaturated vapor exposure, owing to increased crystallinity of the P3HT films; on the other hand, the mobility increases abruptly with saturated vapor exposure, to 0.11 cm2/V s. The saturated vapor exposure causes the P3HT films to reflow, leaving in the active area approximately 2–3 P3HT monolayers whose molecular ordering is enhanced by the flow-generated shear against the gate dielectric. Although the reflowed OTFTs degrade in air much faster than do the non-reflowed OTFTs due to the susceptibility of the ultra-thin reflowed films, they become highly stable when encapsulated, obtaining a lifetime of more than 3000 h. 相似文献
5.
Aiming to environment protection, green solvents are crucial for commercialization of solution-processed optoelectronic devices. In this work, d-limonene, a natural product, was introduced as the non-aromatic and non-chlorinated solvent for processing of polymer light-emitting diodes (PLEDs) and organic field effect transistors (OFETs). It was found that d-limonene could be a good solvent for a blue-emitting polyfluorene-based random copolymer for PLEDs and an alternating copolymer FBT-Th4(1,4) with high hole mobility (μh) for OFETs. In comparisons to routine solvent-casted films of the two conjugated polymers, the resulting d-limonene-deposited films could show comparable film qualities, based on UV–vis absorption spectra and observations by atomic force microscopy (AFM). With d-limonene as the processing solvent, efficient blue PLEDs with CIE coordinates of (0.16, 0.16), maximum external quantum efficiency of 3.57%, and luminous efficiency of 3.66 cd/A, and OFETs with outstanding μh of 1.06 cm2 (V s)−1 were demonstrated. Our results suggest that d-limonene would be a promising non-aromatic and non-chlorinated solvent for solution processing of conjugated polymers and molecules for optoelectronic device applications. 相似文献
6.
Sang-Jin Jeon Jong-Woong Chang Kwang-Soo Choi Jyoti Prakash Kar Tae-Il Lee Jae-Min Myoung 《Materials Science in Semiconductor Processing》2010,13(5-6):320-324
We have studied the characteristics of transparent bottom-gate thin film transistors (TFTs) using In–Ga–Zn–O (IGZO) as an active channel material. IGZO films were deposited on SiO2/Si substrates by DC sputtering techniques. Thereafter, the bottom-gate TFT devices were fabricated by depositing Ti/Au metal pads on IGZO films, where the channel length and width were defined to be 200 and 1000 μm, respectively. Post-metallization thermal annealing of the devices was carried out at 260, 280 and 300 °C in nitrogen ambient for 1 h. The devices annealed at 280 °C have shown better characteristics with enhanced field-effect mobility and high on–off current ratio. The compositional variation of IGZO films was also observed with different annealing temperatures. 相似文献
7.
8.
《Organic Electronics》2007,8(1):44-50
We explore the effects of conventional photo lithographic patterning of the active layer of poly (3-hexylthiophene) (P3HT) organic thin film transistors (OTFT) on device performance. The performance of the devices was monitored in each step of the patterning process. We successfully developed a patterning process which is compatible with plastic substrates and P3HT as the organic semiconductor. In this process, parylene and atomic layer deposition (ALD) Al2O3 were used as capping layers. Al2O3 and parylene/P3HT were etched using Al etchant and O2 plasma reactive ion etching (RIE), respectively. The degradation occurred primarily during the ALD Al2O3 deposition and capping layer etching. There was a 30% degradation in mobility, a 1–2× reduction in drive current, and an increase in threshold voltage after the ALD Al2O3 deposition. In the capping layer etching, a near 50% degradation in mobility was observed. The patterned devices have a mobility of 0.02 cm2/V s, which is 1000× better than photo lithographically patterned P3HT OTFTs previously reported in the literature, and comparable to un-patterned P3HT devices. 相似文献
9.
Indium sulfide (In2S3) thin films are of interest as buffer layers in chalcopyrite absorber based solar cells; and as media providing two-photon absorption for intermediate-band solar cells. We investigated the suitability of chemical spray pyrolysis (CSP) for growing In2S3 thin films in a structural order where indium atoms are preferentially in the octahedral sites. We sprayed aqueous or alcoholic solutions of indium chloride (InCl3) and thiourea (SC(NH2)2) precursors onto a substrate with surface temperatures (TS) of 205, 230, 275 and 320 °C. The as-deposited films grown from aqueous solutions were annealed in 5% H2S containing atmosphere at 500 °C. We used Raman spectroscopy, X-ray diffraction and Energy Dispersive X-ray spectroscopy to evaluate the effect of growth temperature and the effect of annealing on the film structure and stoichiometry. The use of alcoholic solvent instead of aqueous allows us to use much lower TS while preserving the quality of the β-In2S3 films obtained. Similarly, films with increased stoichiometry and quality are present at a higher TS; and when annealed. The annealing of the films grown at TS of 205 °C results in a much higher gain of the crystal quality compared to the gain when annealing the films grown at TS of 320 °C, although the quality remain higher when deposited at TS of 320 °C. Simultaneously with the increase of the film quality, there is a sign of increased quality of the crystal ordering with indium in the octahedral sites. Such a crystal ordering favor the use of CSP deposited In2S3 films in the intermediate band solar cells. 相似文献
10.
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
11.
Mihaela Girtan 《Organic Electronics》2013,14(1):200-205
New photoelectrical properties of poly(3-hexylthiophene-2,5-diyl), highly regioregular (P3HT): Methanofullerene Phenyl-C61-Butyric-Acid-Methyl-Ester [60] PCBM films were putted in evidence. For the first time the electrical conductivity dependencies on temperature in dark and under different illuminations were studied for the P3HT and P3HT:PCBM blend films. These dependencies shows reversible processes and a high sensitivity of the P3HT and P3HT:PCBM to light. The decrease of the resistivity at the exposure to light is of 18% for P3HT films and of 20% for P3HT:PCBM blend films, for a irradiation under 0.5 W/m2 white light at room temperature. By adding the fullerene molecules, in the 1:0.8 polymer:fullerene ratio, the electrical resistivity at room temperature of the blend films decrease compared to the polymer film by 40% in dark, and by 68% under 250 W/m2 white light irradiance.The decrease of the resistivity with the temperature is more pronounced in the presence of light indicating a photon activated process.The existence of the open circuit voltage was evidenced even for planar geometry photodiodes and the values of the open circuit voltage under 1000 W/m2 solar light illumination are coherent with the difference between the work functions of the electrodes. 相似文献
12.
High dielectric constant TiSiOx thin films are produced by reactive sputtering under different oxygen partial pressure ratio (PO2) from 15% to 30%. All the TiSiOx films show an excellent transmittance value of almost 95%. The TiSiOx film has a low leakage current density by optimizing oxygen partial pressure, and the leakage current density of TiSiOx film under PO2 of 20% is 4.88×10−7 A/cm2 at electrical field strength of 2 MV/cm. Meanwhile, their associated InGaZnO thin-film transistors (IGZO-TFTs) with different PO2 TiSiOx thin films as gate insulators are fabricated. IGZO-TFTs under PO2 of 20% shows an optimized electrical performance, and the threshold voltage, sub-threshold swing, field effect mobility and Ion/Ioff ratio of this device are 2.22 V, 0.33 V/decade, 29.3 cm2/V s and 5.03×107, respectively. Moreover, the density of states (DOS) is calculated by temperature-dependent field-effect measurement. The enhancements of electrical performance and temperature stability are attributed to better active/insulator interface and smaller DOS. 相似文献
13.
《Materials Science in Semiconductor Processing》2002,5(2-3):279-284
Low-dielectric constant (low-k) films have been prepared by plasma-enhanced chemical vapor deposition (PECVD) from hexamethyldisiloxane (HMDSO) mixed with oxygen or methane. The films are analyzed by ellipsometry, infrared absorption spectroscopy while their electrical properties are deduced from C–V, I–V and R–f measurements performed on Al/insulator/Si structures. For an oxygen and methane fraction equal to 50% and 22%, respectively, the dielectric constant and losses are decreased compared with those of the film prepared in a pure HMDSO plasma. The effect of adding 22% of CH4 in HMDSO plasma increases the Si–CH3 bonds containing in the polymer film and as the constant of methyl groups in the film increased the dielectric constant of the film decreases. For this film, the dielectric constant is 2.8, the dielectric losses at 1 kHz are equal to 2×10−3, the leakage current density measured for an electric field of 1 MV/cm is 3×10−9 A/cm2 and the breakdown field is close to 5 MV/cm. 相似文献
14.
S.V. Jagadeesh Chandra Chel-Jong Choi S. Uthanna G. Mohan Rao 《Materials Science in Semiconductor Processing》2010,13(4):245-251
The as-deposited and annealed radio frequency reactive magnetron sputtered tantalum oxide (Ta2O5) films were characterized by studying the chemical binding configuration, structural and electrical properties. X-ray photoelectron spectroscopy and X-ray diffraction analysis of the films elucidate that the film annealed at 673 K was stoichiometric with orthorhombic β-phase Ta2O5. The dielectric constant values of the tantalum oxide capacitors with the sandwich structure of Al/Ta2O5/Si were in the range from 14 to 26 depending on the post-deposition annealing temperature. The leakage current density was <20 nA cm?2 at the gate bias voltage of 0.04 MV/cm for the annealed films. The electrical conduction mechanism observed in the films was Poole–Frenkel. 相似文献
15.
Yue Zhao Xiang Peng Yanli Ding Xiaoyan Liang Jiahua Min Linjun Wang Weimin Shi 《Materials Science in Semiconductor Processing》2013,16(6):1472-1477
We studied the growth of CuInS2 thin films by single-source evaporation of CuInS2 powder in a high-vacuum system with a base pressure of 10?3 Pa. After evaporation, the films were annealed in a sulfur atmosphere at temperatures from 200 to 500 °C for 1 h. XRD curves and Raman spectra of the films demonstrated that chalcopyrite CuInS2 was the major crystalline phase. The morphology of CuxS exhibited a star-like structure, which we report for the first time. The phase composition and optical properties of our polycrystalline thin films were effectively modified by annealing in S. For films annealed at 200 and 350 °C, a secondary CuIn11S17 phase appeared, which may be related to solid-state reaction in the S atmosphere. This secondary CuIn11S17 phase has not been widely reported in previous studies. After annealing at 500 °C, only a chalcopyrite phase was detected, with bandgap energy of 1.46 eV, which is nearly identical to the optimal bandgap energy (1.5 eV) of single-crystal CuInS2. This indicates that the composition of the CuInS2 film annealed at 500 °C was nearly stoichiometric. The bandgap of the samples first increased and then decreased with increasing annealing temperature, which may be attributed to an increase in grain size, the secondary CuIn11S17 phase, and deviation from stoichiometry. 相似文献
16.
《Organic Electronics》2014,15(1):251-259
In this study we found that the gelation time and crystallinity of P3HT solid films are adjustable when aging and casting from CHCl3/p-xylene mixed solvents. After aging for 36 h in pure p-xylene, CHCl3, or various mixtures of the two as cosolvents, we found that the solid P3HT film gel-cast from 20 vol% CHCl3 had the highest degree of crystallinity of its main chain (ϕm = 0.54), highest melting point of its main chain (Tm = 232.7 °C), fastest gelation time (30 min), largest melting enthalpy of its main chain (ΔHm = 19.81 J g−1), and lowest resistance (RP = 0.76 MΩ); the latter value was three orders and one order of magnitude lower than those of the films cast from pure CHCl3 (ca. 110 MΩ) and pure p-xylene (ca. 4.4 MΩ), respectively. In differential scanning calorimetry scans, we attribute the presence of melting peaks near 75 °C to the solid-to-solid phase transition of the side chain crystallites of P3HT, thereby affecting the aggregation of the P3HT main chain and resulting in the changes in resistance, crystallinity, melting enthalpy, and melting point of the gel-cast P3HT solid films. 相似文献
17.
《Organic Electronics》2008,9(5):925-929
We have successfully demonstrated a polymeric semiconductor-based transistor with low-k polymer/high-k metal-oxide (TiO2) bilayer as gate dielectric. The TiO2 layers are readily processable from solution and cured at low temperature, instead of traditionally sputtering or high temperature sintering process, thus may suitable for a low-cost organic field effect transistors (FETs) manufacture. The low-k polymer capped on TiO2 layer could further smooth the TiO2 dielectric surface and suppress the leakage current from grain boundary of TiO2 films. The resulting unpatented P3HT-OFETs could operate with supply voltage less than 10 V and the mobility and threshold voltage were 0.0140 cm2/V s and 1.14 V, respectively. The on/off ratio was 1.0 × 103. 相似文献
18.
High-mobility organic single-crystal field-effect transistors of 3,11-didecyldinaphtho[2,3-d:2′,3′-d′]benzo[1,2-b:4,5-b′]-dithiophene (C10-DNBDT) operating at low driving voltage are fabricated by an all-solution process. A field-effect mobility as high as 6.9 cm2/V s is achieved at a driving voltage below 5 V, a voltage as low as in battery-operated devices, for example. A low density of trap states is realized at the surface of the solution-processed organic single-crystal films, so that the typical subthreshold swing is less than 0.4 V/decade even on a reasonably thick amorphous polymer gate dielectrics with reliable insulation. The high carrier mobility and low interface trap density at the surface of the C10-DNBDT crystals are both responsible for the development of the high-performance all-solution processed transistors. 相似文献
19.
M. Kraini N. Bouguila I. Halidou A. Timoumi S. Alaya 《Materials Science in Semiconductor Processing》2013,16(6):1388-1396
In2S3 thin films were grown by the chemical spray pyrolysis (CSP) method using indium chloride and thiourea as precursors at a molar ratio of S:In=2.5. The deposition was carried out at 350 °C on quartz substrates. The film thickness is about 1 µm. The films were then annealed for 2 h at 550, 600, 650 and 700 °C in oxygen flow. This process allows the transformation of nanocrystal In2O3 from In2S3 and the reaction is complete at 600 °C. X-ray diffraction spectra show that In2O3 films are polycrystalline with a cubic phase and preferentially oriented towards (222). The film grain size increases from 19 to 25 nm and RMS values increase from 9 to 30 nm. In2O3 films exhibit transparency over 70–85% in the visible and infrared regions due to the thickness and crystalline properties of the films. The optical band gap is found to vary in the range 3.87–3.95 eV for direct transitions. Hall effect measurements at room temperature show that resistivity is decreased from 117 to 27 Ω cm. A carrier concentration of 1×1016 cm?3 and mobility of about 117 cm2 V?1 s?1 are obtained at 700 °C. 相似文献
20.
Eun Young Park Jin Sun Park Tae-Dong Kim Kwang-Sup Lee Hyun Seok Lim Jong Sun Lim Changjin Lee 《Organic Electronics》2009,10(5):1028-1031
We report on the performance of ink-jet-printed n-type organic thin-film transistors (OTFTs) based on a C60 derivative, namely, C60-fused N-methyl-2-(3-hexylthiophen-2-yl)pyrrolidine (C60TH-Hx). The new devices exhibit excellent n-channel performance, with a highest mobility of 2.8 × 10?2 cm2 V?1 s?1, an IOn/IOff ratio of about 1 × 106, and a threshold voltage of 7 V. The C60TH-Hx films show large crystalline domains that result from the influence of an evaporation-induced flow, thus leading to high electron mobility in the ink-jet-printed devices. 相似文献