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Microelectronics Reliability. 01/2011; 51:676-684.
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ABSTRACT: We report that ZnO nanorods (NRs) are grown on an organic layer of poly(3-hexylthiophene) (P3HT) using a modified seeding layer. Thus, ZnO NRs/P3HT heterojunction light-emitting diodes could be fabricated using the hydrothermal method, in which ZnO acts as an n-type material and P3HT as a p-type material. The ZnO NRs improve the electron transportation in the devices. A three-fold enhancement of current density of the device is observed due to the NRs formed on the P3HT. The electroluminescence (EL) of the optimized ZnO-based device is 1.5 times larger than that without NRs. The influence of the P3HT thickness for the EL spectrum is also discussed.
07/2010;
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ABSTRACT: The ultraviolet (UV) electroluminescence (EL) from the TiO <sub>2</sub>/ ZnO coaxial nanowires (NWs)/poly(3,4-ethylenedioxythiophene)-poly(styrene-sulfonate) inorganic/organic heterostructure devices is greatly enhanced and the defect emission is significantly suppressed compared with the uncoated ZnO NW device at room temperature. The origins of the great changes in EL of ZnO NW devices are attributed to the surface modification of the sputtered TiO <sub>2</sub> coating and the reduction in the pinhole traps on the surface of ZnO NWs. It is found that for the optimized device, the EL intensity ratio between the band gap and defect emission can be greatly enhanced by up to about 250 times its prior level. Such ZnO NW devices with enhanced UV emission have potential applications in the highly efficient solid state emitters.
Journal of Applied Physics 03/2010; · 2.17 Impact Factor
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ABSTRACT: Here, we report the use of organic/inorganic heterostructure to fabricate the p-n heterojunction devices. The heterostructure provides a new approach for constructing high performance electroluminescence devices which improve the balance of hole and electron injection. In this study, we fabricated the white-light inorganic/organic heterojunction diode LEDs, using p-type polymer (PF) and n-type ZnO nanorods (NR). The PF thin films are fabricated by the spin-coating method. ZnO NR array have been produced on PF thin film by hydrothermal method. The device with ZnO NR array shows five fold enhancement of current density at the same voltage. The ZnO enhances electrons and holes to recombine in the interface between ZnO NRs and PF.
Lasers and Electro-Optics 2009 and the European Quantum Electronics Conference. CLEO Europe - EQEC 2009. European Conference on; 07/2009
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ABSTRACT: We report electroluminescence from ZnO nanorod-based devices prepared by the hydrothermal method. The devices composed of ZnO nanorods and P3HT, in which ZnO acts as an n-type material and P3HT acts as a p-type material.
Optical Fiber Communication & Optoelectronic Exposition & Conference, 2008. AOE 2008. Asia; 12/2008
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Nanotechnology, 2008. NANO '08. 8th IEEE Conference on; 09/2008
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ABSTRACT: ZnO nanorod arrays (ZNAs), grown from aqueous solutions, were integrated into polymer solar cells. Morphological, crystalline and optical properties of ZNAs were studied. Infiltration-improved polymer/ZNAs solar cells by adding fullerene were assembled and characterized.
Optical MEMs and Nanophotonics, 2008 IEEE/LEOS Internationall Conference on; 09/2008
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ABSTRACT: The selection of electrodes in ZnO nanorod-based polymer solar cells was investigated. Increases in the work function of metal electrode result in the increases in open-circuit voltage up to 120 mV, leading to improved performance.
Optical MEMs and Nanophotonics, 2008 IEEE/LEOS Internationall Conference on; 09/2008
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ABSTRACT: The characteristics of a nanocomposite consisting of the blue-emitting polymer polyfluorene and ZnO nanowires are reported. The electroluminescence spectrum of the white light emission is from about 400 nm to 750 nm.
Optical MEMs and Nanophotonics, 2008 IEEE/LEOS Internationall Conference on; 09/2008
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ABSTRACT: We report ultraviolet electroluminescence from ZnO nanoparticle-based devices prepared by the dry-coating technique. With dry-coating process, the structure of the ZnO nanoparticle monolayer (90 nm ) in the device can be easily achieved. The method reduces the density of pinhole defects in the ZnO nanoparticles. The confirmation for dry coating is investigated using field-emission scanning electron microscopy. The devices show the ZnO band-gap emission peak at 380 nm and the background emission from the interface between the host matrix and Aluminum tris-8-hydroxyquinoline. The origins of the ZnO band-gap emission and background emission are also discussed.
Applied Physics Letters 07/2008; · 3.84 Impact Factor
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ABSTRACT: This paper investigates the interconnection between the driver integrated circuit (IC) and glass substrate via anisotropic conductive adhesive (ACF) of chip on glass package. The conductive particle deformation is evaluated using a novel method, optical microscope (OM) inspection. The proposed method is more convenient than the traditional approach using scanning electron microscopy applied in the manufacturing process. Interconnection performance is easily judged using OM, allowing poor interconnection between the driver IC and glass substrate to be screened out. Several types of driver ICs with different bump area ratios (total input bump area/total output bump area, input/output ratio) and length/width (L/W) ratios are designed in this experiment. The conductive particle deformations are investigated in this study. Driver ICs with L/W ratios larger than 15 have better conductive particle deformation uniformity at each position. The average deformation degree at the driver IC center position is larger than that at the side and edge positions. The deformation degree at the input position with a smaller bump area is better than that at the output position. The conductive resistance increases with the reliability testing time because of the thermal stress effect and softening of the ACF polymer material. The deformation degree is related to the conductive resistance of the interconnection. The conductive resistance is lower at the center and input positions with larger deformation degree.
IEEE Transactions on Components and Packaging Technologies 07/2008; · 0.94 Impact Factor
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ABSTRACT: We report the visible light emission of organic-inorganic light emitting devices by low-cost spin-coating. Different nanoparticles, CdSe, ZnO and Eu<sub>2</sub>O<sub>3</sub>, are employed to form organic-inorganic hybrid composites and generate the R-G-B and white light emission, while N,N'-diphenyl-N,N'-bis(3-methylphenyl)-1,1'-biphenyl-4,4'-diamine (TPD) and polymethyl methacrylate (PMMA) are adopted as the organic matrices. We further investigate the hybrid composite film by scanning near-field optical microscope and find that phase-segregation enhances the electroluminescence of ZnO composite film. Meanwhile, the homogeneity of the Eu<sub>2</sub>O<sub>3</sub> composite film improves the white light emission.
Nanotechnology, 2007. IEEE-NANO 2007. 7th IEEE Conference on; 09/2007
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ABSTRACT: We report the white light emission of hybrid N,N'-diphenyl-N,N'-bis(3-methylphenyl)-1, 1'- biphenyl-4,4'-diamine (TPD) / europium oxide (Eu<sub>2</sub>O<sub>3</sub>) nanocrystals composite by spin-coating. The organic-inorganic hybrid film consists of Eu<sub>2</sub>O<sub>3</sub> nanocrystals, TPD and polymethyl methacrylate (PMMA). The bandwidth of the white light emission spans as wide as 300 nm, which is attributed to the interaction between the organic and inorganic components of the hybrid film. The peak wavelength of the electroluminescence is tuned from 550 nm to 410 nm, when the forward biased voltage increases from 6 V to 9 V. We further investigate the hybrid film by scanning near-field optical microscope and confirm that PMMA improves the film quality and hence the luminescence.
Nanotechnology, 2007. IEEE-NANO 2007. 7th IEEE Conference on; 09/2007
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ABSTRACT: The authors report ultraviolet electroluminescence from ZnO nanoparticle-based devices prepared by the phase-segregation technique. The conditions for phase segregation are investigated using confocal microscopy. With proper parameters for phase segregation, the ZnO nanoparticles and N,N′-diphenyl-N,N′-bis(3-methylphenyl)-1,1′-biphenyl-4,4′-diamine: poly(methyl methacrylate) can be separated into two layers upon spin-coating process. The method allows electrons and holes to recombine in the ZnO nanoparticles. The I-V curve shows stable and excellent rectification. For the device with 90 nm ZnO nanoparticles, it exhibits a very narrow spectrum with a peak at 392 nm and no defect-related emission. The emission peak well corresponds to the ZnO band-gap energy.
Applied Physics Letters 12/2006; 89(23):231116-231116-3. · 3.84 Impact Factor
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Meng-Yueh Liu,
Chin-Hsiang Chang,
Chih-Hua Chang,
Kao-Hua Tsai,
Jing-Shun Huang,
Chen-Yu Chou,
Ing-Jye Wang,
Po-Sheng Wang, Chun-Yu Lee,
Cha-Hsin Chao,
Chin-Liang Yeh,
Chih-I Wu,
Ching-Fuh Lin
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ABSTRACT: The inverted polymer solar cell (PSC) based on a sol–gel derived zinc oxide (ZnO) thin film as an electron selective layer is investigated. The device performance is improved after the fabricated device is placed in air for a few days. The improvement is attributed to the self-organization of the poly(3-hexylthiophene)/[6,6]-phenyl-C61-butyric acid methyl ester layer and oxidation of the silver electrode with time, resulting in a significant enhancement in the short circuit current, fill factor and open circuit voltage. The investigation shows that the inverted PSC based on ZnO thin film exhibits a high efficiency of 3.8% on the 6th day after fabrication without the use of poly(3,4-ethylene dioxythiophene):poly(styrene sulfonate) and encapsulation.
Thin Solid Films 518(17):4964-4969. · 1.89 Impact Factor
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ABSTRACT: Lengthening the polymer solidification time in the inverted configuration of polymer/ZnO nanorod hybrid solar cells is studied as a way to improve device performance. As the polymer solidification time is lengthened by lowering the spin-coating rate of the photoactive layer, the photoactive layer becomes thickened, and the polymer chains have enough time to self-organize and effectively infiltrate into ZnO nanorod spacing. While the thickness of the photoactive layer is increased to 400 nm accompanying self-organized polymer, the power conversion efficiency of the device is improved to 3.58% with an enhanced fill factor of 58%. The 400 nm film is composed of the highly ordered polymer and the ZnO nanorod arrays, resulting in light harvesting without decreasing the possibility for charge transport.
Solar Energy Materials and Solar Cells.
