共查询到20条相似文献,搜索用时 156 毫秒
1.
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
2.
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
3.
Xifeng Li Enlong Xin Longlong Chen Jifeng Shi Chunya Li Jianhua Zhang 《Materials Science in Semiconductor Processing》2013,16(5):1292-1296
Bottom-gate transparent IGZO–TFT had been successfully fabricated at relatively low temperature (200 °C). The devices annealing for 4 h at 200 °C exhibit good electrical properties with saturation mobility of 8.2 cm2V?1s?1, subthreshold swing of 1.0 V/dec and on/off current ratio of 5×106. The results revealed that the stability of TFT devices can be improved remarkably by post-annealing treatment. After applying positive gate bias stress of 20 V for 5000 s, the device annealing for 1 h shows a larger positive Vth shift of 4.7 V. However, the device annealing for 4 h exhibits a much smaller Vth shift of 0.04 V and more stable. 相似文献
4.
This paper reports polymer solar cells with a 7% power conversion efficiency (PCE) based on bulk heterojunction (BHJ) composites of the alternating co-polymer, poly[N-9′′-hepta-decanyl-2,7-carbazole-alt-5,5-(4′,7′-di-2-thienyl-2′,1′,3′-benzothiadiazole) (PCDTBT), and the fullerene derivative [6,6]-phenyl C71-butyric acid methyl ester (PC71BM). As confirmed by transmission electron microscopy, solvent–vapor annealing (SVA) of the thin (70 nm) BHJ photoactive layer by exposure to chloroform vapor, for a short period of time (30 s) after deposition, leads to reconstructed nanoscale morphology of donor/acceptor domains, well-dispersed fullerene phase and effective photo-absorption of BHJ. Consequently, SVA-reconstructed devices with a PCDTBT:PC71BM blend ratio of 1:5 (wt%) exhibit ~50% improvement in PCE, with short-circuit current Jsc = 15.65 mA/cm2, open-circuit voltage Voc = 0.87 V, and PCE = 7.03%, in comparison to those of the 1:4 (wt%) blends with SVA treatment. 相似文献
5.
In this work, graphene oxide (GO) reduced by thermal annealing was employed as a hole transport layer (HTL) in bulk heterojunction (BHJ) solar cells. Considering the insulating property of nonreduced GO, the annealing temperature plays an important role in recovering the conjugated structure of the graphene sheet, and thereby the conductivity of GO. BHJ solar cells with high-temperature (e.g., 230 °C) reduced GO as the HTL showed much larger fill factor (FF) than devices with low-temperature (e.g., 130 °C) reduced GO as the HTL, indicating the better conductivity of GO annealed at an elevated temperature due to the removal of oxygen functional groups from the graphene sheet to a much-higher level. On the other hand, the work function of GO may be lowered toward that of graphene (4.5 eV) with increasing the reduction temperature, which results in a decreased open-circuit voltage (Voc) for the high-temperature reduced GO devices. By further optimizing the concentration and spin-coating speed of GO dispersion, we achieved a power conversion efficiency (PCE) that is 26% higher than devices without any HTL. This is mainly attributed to the increase in FF as a result of the decreased series resistance (Rs). In addition, the PCE of the optimized GO device was ~85% of the PCE of the conventional device with poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) HTL. We anticipate that further optimization of the reduction conditions (e.g., using chemical reductants) will lead to the better performance of GO solar cells. 相似文献
6.
Xiangjian Wan Yongsheng Liu Fei Wang Jiaoyan Zhou Guankui Long Yongsheng Chen 《Organic Electronics》2013,14(6):1562-1569
A solution processable A-D-A-D-A structure small molecule DCAEH5TBT using a BT unit as the core has been designed and synthesized for application in BHJ solar cells. The device employing DCAEH5TBT/PC61BM as active layer shows PCE of 2.43% without any post treatment. After thermal annealing (150 °C, 10 min), the PCE of this molecule based device increased to 3.07%, with Jsc of 7.10 mA/cm2, Voc of 0.78 V and FF of 55.4%, which indicates that high performance of solution processed small molecule based solar cells can be achieved using thermal annealing by carefully design molecule structure. 相似文献
7.
《Organic Electronics》2008,9(6):1061-1068
We have investigated a series of oligothiophenes in organic thin film transistors (TFTs), with special emphasis on their thin film morphology related to device performance and application requirements. The transistor performance was studied for devices fabricated at different substrate temperatures during semiconductor deposition (ranging from room temperature to 120 °C). A significant dependence of thin film morphology on the substrate temperature was observed, whereas the charge carrier mobility in devices occurs almost unaffected. We have tested the long-term stability of 78 transistor devices (shelf-life in ambient conditions) over a period up to 100 days. Only a small degradation in mobility by less than one order of magnitude was observed. Investigations at elevated temperatures during TFT operation (room temperature to 105 °C) show that devices with α,α′-hexylsexithiophene (Hex-6T-Hex) degrade in their charge carrier mobility by a factor of 8, but completely recover to their initial value of 0.7 cm2/Vs after a short period of storage at room temperature in ambient conditions. 相似文献
8.
We studied the electrical properties of organic photovoltaic (OPV) devices based on poly (3-hexylthiophene) and fullerene derivative [6, 6]-Phenyl-C70-butyric acid methyl ester nanocomposite (P3HT:PC70BM) as a function of the annealing temperature. Thermal annealing enables crystallization of the polymer and diffusion of the PC70BM molecules. Diode parameters, such as the barrier height ϕb and the ideality factor n were calculated. They were found to be depend strongly on the annealing temperature. This dependence is attributed to surface states, inhomogeneity in the material and series resistance. Best OPV devices had a short circuit current density of 3.35 mA/cm2, an open circuit voltage of 0.68 V, a fill factor of 0.45, and a power conversion efficiency of 2.2%, by applying a thermal annealing temperature of 150 °C for 10 min. 相似文献
9.
Two molecules denoted as VC96 and VC97 have been synthesized for efficient (η = 6.13% @ 100 mW/cm2 sun-simulated light) small molecule solution processed organic solar cells. These molecules have been designed with the D1-A-D2-A-D1 structure bearing different central donor unit, same benzothiadiazole (BT) as π-acceptor and end capping triphenylamine. Moreover, the optical and electrochemical properties (both experimental and theoretical) of these molecules have been systematically investigated. The solar cells prepared from VC96:PC71BM and VC97:PC71BM (1:2) processed from CF (chloroform) exhibit a PCE (power conversion efficiency) of η = 4.06% (Jsc = 8.36 mA/cm2, Voc = 0.90 V and FF = 0.54) and η = 3.12% (Jsc = 6.78 mA/cm2, Voc = 0.92 V and FF = 0.50), respectively. The higher PCE of the device with VC96 as compared to VC97 is demonstrated to be due to the higher hole mobility and broader IPCE spectra. The devices based on VC96:PC71BM and VC97:PC71BM processed with solvent additive (3 v% DIO, 1,8-diiodooctane) showed PCE of η = 5.44% and η = 4.72%, respectively. The PCE device of optimized VC96:PC71BM processed with DIO/CF (thermal annealed) has been improved up to 6.13% (Jsc = 10.72 mA/cm2, Voc = 0.88 V and FF = 0.61). The device optimization results from the improvement of the balanced charge transport and better nanoscale morphology induced by the solvent additive plus the thermal annealing. 相似文献
10.
Sachetan M. Tuladhar Marc Sims Stelios A. Choulis Christian B. Nielsen Wayne. N. George Joachim H.G. Steinke Donal D.C. Bradley Jenny Nelson 《Organic Electronics》2009,10(4):562-567
We report on studies of poly-(2,5-dihexyloxy-p-phenylenevinylene) (PDHeOPV), a symmetric side-chain polymer, as a potential new donor material for polymer:fullerene blend solar cells. We study the surface morphology of blend films of PDHeOPV with PCBM, the transport properties of the blend films, and the performance of photovoltaic devices made from such blend films, all as a function of PCBM content. In each case, results are compared with those obtained using the asymmetric side chain polymer, poly[2-methoxy-5-(3,7-dimethyloctyloxy)-1,4-phenylenevinylene] (MDMO-PPV), in order to investigate the influence of polymer side chain symmetry on solar cell performance. AFM images show that large PCBM aggregates appear at lower PCBM content (50 wt.% PCBM) for PDHeOPV:PCBM than for MDMO-PPV:PCBM (67 wt.% PCBM) blend films. Time-of-Flight (ToF) mobility measurements show that charge mobilities depend more weakly on PCBM content in PDHeOPV:PCBM than in MDMO:PPV:PCBM, with the result that at high PCBM content the mobilities in PDHeOPV:PCBM are significantly lower than in MDMO:PPV:PCBM blend films, despite the higher mobilities in pristine PDHeOPV compared to pristine MDMO-PPV. Photovoltaic devices show significantly lower power conversion efficiency (~0.93%) for PDHeOPV:PCBM (80 wt.% PCBM) blend films than for MDMO-PPV:PCBM (2.2% at 80 wt.% PCBM) blends. This is attributed to the relatively poor transport properties of the PDHeOPV:PCBM blend, which limit the optimum thickness of the photoactive layer in PDHeOPV:PCBM blend devices. The behaviour is tentatively attributed to a higher tendency for the symmetric side-chain polymer chains to aggregate, resulting in poorer interaction with the fullerene and poorer network formation for charge transport. 相似文献
11.
《Organic Electronics》2008,9(6):952-958
The thin-film morphologies and thin-film transistor (TFT) characteristics of a series of binary blends of poly(9,9′-dioctylfluorene-alt-bithiophene) (F8T2) and α,ω-dihexylquarterthiophene (DH4T) are reported. The blends of F8T2 and DH4T exhibit good solubility and produce TFT devices with better performances than F8T2 and DH4T devices. The 50% DH4T blend device was found to have a hole mobility of 0.011 cm 2 V−1 s−1, which is four times higher than the mobility of the F8T2 device, with a high-on/off ratio of about 105 and a low-off current of 17 pA. The polymer and oligomer domains are phase-separated with large domain size and arranged in characteristic molecular alignments. It was found that carrier transport in the blend systems is mainly controlled by the polymer component, and that the nature of the blended oligomer affects the OTFT performance of the blends. 相似文献
12.
《Materials Science in Semiconductor Processing》2009,12(6):238-242
Effects of thermal annealing on the morphology of the AlxGa(1−x)N films with two different high Al-contents (x=0.43 and 0.52) have been investigated by atomic force microscopy (AFM). The annealing treatments were performed in a nitrogen (N2) gas ambient as short-time (4 min) and long-time (30 min). Firstly, the films were annealed as short-time in the range of 800–950 °C in steps of 50–100 °C. The surface root-mean-square (rms) roughness of the films reduced with increasing temperature at short-time annealing (up to 900 °C), while their surface morphologies were not changed. At the same time, the degradation appeared on the surface of the film with lower Al-content after 950 °C. Secondly, the Al0.43Ga0.57N film was annealed as long-time in the range of 1000–1200 °C in steps of 50 °C. The surface morphology and rms roughness of the film with increasing temperature up to 1150 °C did not significantly change. Above those temperatures, the surface morphology changed from step-flow to grain-like and the rms roughness significantly increased. 相似文献
13.
《Organic Electronics》2014,15(4):878-885
Comparative studies of the effects of a series of polycrystalline donors on the performance of 95 wt.%-C70-based bulk-heterojunction (BHJ) photovoltaics were conducted. A BHJ based on the wide band-gap molecule dinaphthothienothiophene (DNTT) shows power conversion efficiency (ηPCE) of up to 4.28%. The photovoltaic parameters are superior to those of devices using the similar molecule pentacene (PEN) or polycrystalline copper phthalocyanine (CuPc) for donor concentrations from 5 to 30 wt.%. The low-lying DNTT ionization potential and the high μh in the DNTT blend support the excellent DNTT device performance. The low performance of BHJs with 5 wt.% PEN and 5 wt.% CuPc may stem from strong exciplex recombination in the PEN:C70 blend and limited hole mobility combined with geminate polaron-pair recombination in the CuPc:C70 blend. The zero-field hole mobility of the blends with 5 wt.% donor has a positive correlation with the corresponding device performance. The ηPCE of a 5 wt.%-DNTT BHJ cell was improved to 4.92% by optimizing the cathode buffer layer. 相似文献
14.
Yoonseok Ka Eungkyu Lee Si Yun Park Jaewon Seo Dae-Gyeon Kwon Hyun Hwi Lee Yongsup Park Youn Sang Kim Changsoon Kim 《Organic Electronics》2013,14(1):100-104
We investigate the effects of ZnO annealing temperature (TA) on the performance of inverted polymer solar cells with ZnO electron-selective layers deposited by spin coating aqueous solutions of an ammine-hydroxo zinc complex. The inverted solar cells based on poly(3-hexylthiophene):[6,6]-phenyl-C61-butyric acid methyl ester with TA as low as 80 °C exhibit power-conversion efficiencies of 3.6%, which is equal to those of devices with higher TA. Characterizations of the ZnO films using X-ray photoelectron spectroscopy, ultraviolet photoelectron spectroscopy, grazing incidence wide-angle X-ray scattering, and optical transmittance measurements show that the abrupt improvement of device performance from TA = 60 to 80 °C is due to the improvement of energy-level alignment arising from the increases in the relative amount and the crystallinity of ZnO. 相似文献
15.
Ning Wang Xichang Bao Chunpeng Yang Jun Wang Han Young Woo Zhenggang Lan Weichao Chen Renqiang Yang 《Organic Electronics》2013,14(2):682-692
A series of indole-substituted fulleropyrrolidine derivatives with different side groups on a pyrrolidine rings, including methyl (OIMC60P), benzyl (OIBC60P), 2,5-difluoroinebenzyl (OIB2FC60P), and 2,3,4,5,6-pentafluoroinebenzyl (OIB5FC60P), have been synthesized and used as electron acceptor in the active layer of polymer-fullerene solar cells to investigate the effect of various substitute groups on the electronic structures, morphologies, and device performances. Optical absorption, electrochemical properties and solubility of the fullerene derivatives have been explored and compared. The inverted photovoltaic devices with the configuration ITO/ZnO/Poly(3-hexylthiophene)(P3HT):[60]fullerene derivatives/MoO3/Ag have been prepared including the reference cell based on the P3HT: methyl [6,6]-phenyl-C61-butylate (PCBM) blend films. All the devices properties were measured in air without encapsulation. We also investigated the effect of the thermal annealing on the crystallinity and morphology of the active layer and the device performance. The device based on the blend film of P3HT and OIBC60P showed a power conversion efficiency of 2.46% under illumination by AM1.5G (100 mW/cm2) after the annealing treatment at 120 °C for 10 min in air. 相似文献
16.
We present a ternary strategy to enhance the power conversion efficiency (PCE) of bulk heterojunction polymer solar cells (PSCs) with a bipolar small molecule as cascade material. A bipolar diketopyrrolopyrrole small molecule (F(DPP)2B2), as the second electron acceptor, was incorporated into poly(3-hexylthiophene) (P3HT): [6,6]-phenyl-C61-butyric-acidmethyl-ester (PC61BM) blend to fabricate ternary blend PSCs. The introduction of the bipolar compound F(DPP)2B2 can not only broaden the light absorption of the active layer because of its absorption in near infrared region but also play a bridging role between P3HT and PC61BM due to the cascaded energy level structure, thus improving the charge separation and transportation. The optimized ternary PSC with 5 wt% F(DPP)2B2 content delivered a high PCE of 3.92% with a short-circuit current density (Jsc) of 9.63 mA cm−2, an open-circuit voltage (Voc) of 0.62 V and a fill factor (FF) of 64.90%, showing an 23% improvement of PCE as compared to the binary systems based on P3HT:PC61BM (3.18%) or P3HT:F(DPP)2B2 (3.17%). The results indicate that the ternary PSCs with a bipolar compound have the potential to surpass high-performance binary PSCs after carefully device optimization. 相似文献
17.
《Organic Electronics》2014,15(2):470-477
We demonstrate that one-dimensional photonic crystals as distributed Bragg reflectors can effectively improve the performance of semitransparent polymer solar cells (PSCs) based on the blend of P3HT:ICBA. The one dimensional distributed Bragg reflectors (1D DBRs) are composed of N pairs of WO3/LiF which are thermally evaporated on Ag anode. Due to its photonic bandgap, 1D DBRs can reflect the light totally back into the PSCs when the high reflectance range of 1D DBRs is well matched with absorption spectrum of the active layer. A maximum power conversion efficiency (PCE) of 4.12%, a highest transmittance of 80.4% at 660 nm and an average transmittance of 55.6% in the wavelength range of 600–800 nm are obtained in the case of N = 8, corresponding enhancement of 24.1% in PCE when compared with the device without the 1D DBRs. 相似文献
18.
K. Čičo D. Gregušová J. Kuzmík M. Jurkovič A. Alexewicz M.-A. di Forte Poisson D. Pogany G. Strasser S. Delage K. Fröhlich 《Solid-state electronics》2012,67(1):74-78
We report on preparation and electrical characterization of InAlN/AlN/GaN metal–oxide–semiconductor high electron mobility transistors (MOS HEMTs) with Al2O3 gate insulation and surface passivation. About 12 nm thin high-κ dielectric film was deposited by MOCVD. Before and after the dielectric deposition, the samples were treated by different processing steps. We monitored and analyzed the steps by sequential device testing. It was found that both intentional (ex situ) and unintentional (in situ before Al2O3 growth) InAlN surface oxidation increases the channel sheet resistance and causes a current collapse. Post deposition annealing decreases the sheet resistance of the MOS HEMT devices and effectively suppresses the current collapse. Transistors dimensions were source-to-drain distance 8 μm and gate width 2 μm. A maximum transconductance of 110 mS/mm, a drain current of ~0.6 A/mm (VGS = 1 V) and a gate leakage current reduction from 4 to 6 orders of magnitude compared to Schottky barrier (SB) HEMTs was achieved for MOS HEMT with 1 h annealing at 700 °C in forming gas ambient. Moreover, InAlN/GaN MOS HEMTs with deposited Al2O3 dielectric film were found highly thermally stable by resisting 5 h 700 °C annealing. 相似文献
19.
《Organic Electronics》2014,15(7):1387-1395
Higher electrical charge carrier mobility in polymer semiconductor films is important to build electronic and opto-electronic devices with improved performance. Application of electric field of the order of 2000 V cm−1 during the solvent drying step for the formation of poly (3-hexyl thiophene-2,5-diyl) (P3HT) film is shown to significantly increase the hole carrier mobility. The reasons for increase in mobility by this novel technique are investigated in this paper. The X-ray diffraction measurements confirm the increase in crystallinity of the films for electric-field annealed samples, while the analysis of the data shows increase in the size of the ‘crystallites’ in those films. The current density–voltage data corresponding to the space charge limited currents at various low temperatures for hole-only devices with P3HT film when fitted to the empirical model for electric-field annealed samples, show an increase in zero field mobility (μ0) and correspondingly a decrease in activation energy (Ea) and the field dependence pre-factor (γ). The data fitted to the Gaussian disorder model also shows a decrease in the energetic disorder (σ) in the polymer films due to electric-field annealing – indicative of increased ordering of molecules in those films. The analysis confirms the improvement of ordering of the polymer in the film formed due to application of electric field during the solvent drying step of the film formation – a simple processing technique which may be implemented to fabricate higher mobility polymer films for building improved organic electronic devices. 相似文献
20.
Fuzhi Wang Liangjie Li Qi Xu Deping Qian Shusheng Li Zhan’ao Tan 《Organic Electronics》2013,14(3):845-851
We demonstrate efficient polymer solar cells (PSCs) based on poly(3-hexylthiophene) (P3HT) and fullerene derivatives ether Indene-C60 Bisadduct (IC60BA) or Indene-C70 Bisadduct (IC70BA)) by using solution-processed titanium(IV) oxide bis(2,4-pentanedionate) (TOPD) as electron collection layer (ECL) between the Al cathode and photoactive layer. The TOPD buffer layer was simply prepared by spin-coating isopropanol solution of TOPD on active layer and then baked at 80 °C for 15 min. The short-circuit current density (Jsc) and the open-circuit voltage (Voc) of the devices can be simultaneously and significantly improved by optimizing the electron collection layer, the photoactive layer and the device fabrication conditions. The power conversion efficiency (PCE) of the P3HT:IC60BA BHJ device with TOPD buffer layer reaches 5.0% under the illumination of AM1.5G, 100 mW/cm2, which is increased by 27% in comparison with that (3.9%) of the device without TOPD buffer layer under the same experimental conditions. When IC70BA was chosen instead of IC60BA, the BHJ device could show better performance with PCE of 5.59%. The results indicate that TOPD is a promising electron collection layer for PSCs. 相似文献