Ultra-Violet Electroluminescence of ZnO Nanorods/MEH-PPV Heterojunctions by Optimizing Their Thickness and Using AZO as a Transparent Conductive Electrode.

In this paper, a series of ITO/ZnO/ZnO nanorods/MEH-PPV/Al were prepared with different thicknesses of MEH-PPV that were changed from 15, 10 to 7 nm. The electric field in the devices was analyzed. An increase in the electric field on ZnO made hole injection easy and the electrons tunnel fast through thinner MEH-PPV to ZnO.

Study on the Overshoot Effect of Doped PhOLED with Transient Electroluminescence.

The accumulation carriers and the trapped carriers are found in many organic light-emitting diodes (OLEDs) more or less, which can lead to a great loss of carriers and weaken the performance of devices. We have investigated a host-guest-system containing the green phosphorescent emitter tris[2-phenylpyridinato-C2,N]iridium(Ⅲ) [Ir(ppy)3] and one host material with transient electroluminescence (EL). The charge recombination, accumulation and light emission mechanisms of the phosphorescent organic light-emitting diodes (PhOLEDs) with different host materials were analyzed.

[The Inside Charge Behavior of Organic Light-Emitting Diodes Investigated with Transient Electroluminescent Measurements].

Transient electroluminescent measurement system is used to study the inside charge behavior of prepared organic light-emitting diodes (OLEDs) in this article. Two rectangular pulses with a fixed time interval are supplied on the device. We can analyze the inside charge storage and the emitting process by measuring the transient EL and transient current of the device.

[Understanding the Effected Efficiencies of Polymer Solar Cells Employing Different Fullerene Multiadducts as Acceptors].

The application of fullerenes with two or more adducts as acceptors has greatly enhanced the performance of bulk-heterojunction solar cells with poly (3-hexylthiophene) (P3HT) as the donor. The enhancement is caused by a substantial increase in the open-circuit voltage due to a rise in the fullerene lowest unoccupied molecular orbital (LUMO) level when going from monoadducts to multiadducts. While the increase in the open-circuit voltage is obtained with many different polymers, most polymers other than P3HT show a substantially reduced photocurrent when blended with fullerene multi-adducts such as bis adduct of Phenyl-C61 -butyric acid methyl ester (bis-PCBM) or the indene-C60 bis-adduct (ICBA).

[Effect of annealing pressure on P3HT : PCBM nanoscale morphology and photovoltaic properties].

The considerable performance enhancement of P3HT-based solar cell after thermal annealing can be attributed to the thermodynamically driven partial crystallization and phase segregation of each component. In the present work, thermal annealing was executed by delivering P3HT : PCBM blend films onto the preheated susceptor in a PECVD chamber filled with high purity nitrogen gas. The pressure of inner chamber could be set steadily and precisely in the range of 1 to 1 850 mTorr at 150 °C.

[A new method to improve the luminous efficiency of organic light-emitting device: metal thin layer].

Inserting metal thin layer into organic electroluminescent device often brings some unexpected effect. By inserting 5 nm Au thin layer between MoO3 and TPD, we prepared the OLED device with the structure of ITO/MoO3(5 nm)/Au(5 nm)/ TPD/AlQ/LiF/Al. The luminous efficiency is improved as compared to the device without the Au.

[Improved color purity of green OLED device based on Au thin film].

Au was used as anode in some kind of organic electroluminescent devices. Sometimes transparent Au electrodes are required, which means that the thickness of Au electrode should be as thin as possible. Therefore, two metals together forming an electrode become a choice.

[Study on the safety of blue light leak of LED].

In this paper, the blue light properties of LED illumination devices have been investigated. Against the status quo of China's LED lighting, we measured the spectrum component of LED lamps and analyzed the photobiological safety under the current domestic and international standards GB/T 20145-2006/CIE S009/E: 2002 and IEC62471: 2006 standards as well as CTL-0744_2009-laser resolution, which provides the reference to the manufacture of LED lighting lamps as well as related safety standards and laws. If the radiance intensity of blue light in LED is lower than 100 W x m(-2) x Sr(-1), there is no harm to human eyes.

Heterojunction of ZnO nanoparticle/PMMA and its ultraviolet electroluminescence.

A ZnO nanoparticle layer was synthesized by the sol-gel method on ITO glass. Devices with a ZnO nanoparticle layer/polymethylmethacrylate (PMMA) heterojunction structure were then fabricated and the room temperature electroluminescence (EL) spectra were studied. Under DC bias, ultraviolet (UV) EL at 390 nm from the ZnO band edge emission was observed, and defect-related emission of ZnO at 600 and 760 nm were also detected.

[White organic light-emitting diodes applied for lighting technology].

Lighting accounts for approximately 22 percent of the electricity consumed in buildings in the United States, with 40 percent of that amount consumed by inefficient incandescent lamps. This has generated increased interest in the use of white electroluminescent organic light-emitting devices (WOLEDS) as the next generation solid-state lighting source, owing to their potential for significantly improved efficiency over incandescent sources, combined with low-cost, high-throughput manufacturability. The research and application of the devices have witnessed great progress.

[Tunneling electroluminescence of the ZnO nanorods/MEH-PPV heterojunction devices].

In the present paper, zinc oxide nanorods (ZnO-NRs) were synthesized by the hydrothermal method at lower temperature and the polymer poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV) were used to fabricate an electroluminescent device based on the structure of "ITO/ZnO-seed/ZnO-NRs/MEH-PPV/Al". The measurement of current-voltage curve shows that it has a well rectifying characteristic. When a reverse bias exceeding 17 volts was applied to the ZnO-NRs/ MEH-PPV heterojunction, both emissions of ZnO and MEH-PPV were detected.

[Bulk heterojunction solar cell based on porphyrin compounds].

Three kinds of porphyrins which can abbreviate as TPP, TPPCu and TMPPFeCl were synthesized by one-step method with mixed solvents. Then these porphyrin materials were used as donors to fabricate organic solar cells with PCBM as accepter by the solution processing of spin-coating method. The structure is ITO/porphyrin : PCBM/Al.

[Luminescence characteristics of PVK doped with Eu-complex Eu(UVA)3Phen].

The present work investigates the photoluminescence (PL) and electroluminescence (EL) characteristics of Eu-complex Eu (UVA)3Phen doped PVK with different doping concentrations. The results indicate that there exists Forster energy transfer from PVK to Eu(UVA)3 phen in the mixed system. It can get good color purity by optimizing the doping concentration of host and guest materials.

[Luminescence characteristics of PVK doped with Ir(Fppy)3].

In the present work, the photoluminescence (PL) and electroluminescence (EL) characteristics of Tris[2-(2,4-difluorophenyl)pyridine]iridium(III) (Ir(Fppy)3) doped poly(n-vinylcarbazole) (PVK) with different doping concentrations were investigated. And a blue phosphorescent organic light-emitting diode (OLED) with the structures of ITO/PEDOT : PSS/PVK : Ir(Fppy)3/BCP/Alq3/LiF/Al was fabricated. The experimental results show that the luminescence performances of devices are different as the doping concentration of Ir(Fppy)3 is different.

[Value of contrast-enhanced ultrasound imaging in monitoring malignant tumor during argon-helium cryosurgery].

Objective: To assess the value of contrast-enhanced ultrasound imaging in monitoring the therapeutic effect of argon-helium cryosurgical treatment of malignant tumors.

Methods: Before and after argon-helium cryosurgical treatment, 42 patients underwent contrast-enhanced ultrasound imaging, conventional ultrasound imaging and enhanced CT or magnetic resonance imaging (MRI) for examining the number of tumor foci and the size of necrotic areas.

Results: A total of 80 tumor lesions were detected by contrast-enhanced ultrasound imaging.

[Study on the movement of the carrier recombination region in organic light-emitting diodes (OLEDs) based on DPVBi/Alq3].

Series of organic light emitting devices with basic structure of ITO/PCBM: PVK(x Wt%, approximately 40 nm)/DPVBi(30 nm)/Alq3 (30 nm)/Al were fabricated in order to investigate the carrier recombination region movement in these devices. The carrier injection-dependent, the carrier transport-dependent and the voltage-dependent carrier recombination region movements were investigated respectively by modifying cathode with lithium fluoride, by changing the doping concentration of PCBM and by changing the voltage on the devices. The physical mechanism behind the voltage-dependent carrier recombination region movement was discussed.

[Effect of mixed interface on the performance of solution-processed phosphorescent OLEDs].

In the present work, in order to improve electron injection and transport at the interface of the hole blocking layer (HBL) and the electron transport layer (ETL) in the hole-domain solution processed phosphorescent organic light emitting devices (PhOLEDs), the mixed interface layer (MIL) was fabricated by partially co-doping hole blocking material 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP) and electron transport material tris(8-quinolinolato) aluminum (Alq3) between HBL/ ETL. The MIL thickness was kept at 10nm, while the doping ratio of these two materials varied. Under a given electric field, the devices with the MIL at any mixed ratios all show much higher luminance and current density than those with a typical interface.

[Effects of hole-injection layers on the performance of blue organic light-emitting diodes].

The present work investigates the effects of different buffer layers on the performance of blue organic light-emitting diodes (OLEDs), and compares them with the device with no buffer layer. Two kinds of blue OLEDs with 4,4'-bis(2,2'-diphenyl vinyl)-1,1'-biphenyl (DPVBi) as the emitting layer, N, N'-bis-(1-naphthyl)-N, N'-1-diphenyl-1,1 '-biphenyl-4, 4'-diamine (NPB) as the hole transporting layer, and copper phthalocyanine (CuPc) and poly(3,4-ethylenedioxythiophene) : poly (styrenesulphonate) PEDOT : PSS as the hole injection layer respectively were fabricated with the structures of ITO/CuPc/NPB/DPVBi/BCP/Alq3 /Al and ITO/PEDOT : PSS/NPB/DPVBi/BCP/Alq3/Al. Moreover, the effects of different preparation technology of CuPc on the performance of OLEDs were also investigated.

[Influence of the active layer thickness on the performance of bulk heterojunction solar cell].

Bulk heterojunction polymer solar cells based on the blend of MEH-PPV (poly[2-methoxy-5-(2'-ethylhexyloxy)-1,4-phenylenevinylene]) and PCBM (1-(3-mehyloxycarbonyl)propyl-phenyl[6,6]C61) were fabricated. The thickness of the active layer was controlled by changing the concentration of MEH-PPV : PCBM (1 : 4 in weight ratio) solution and spin speeds. Investigation of the effects of active layer thicknesses on the performance of the photovoltaic devices indicates that, when the spin-coated speeds are lower than 4,000 r x min(-1) (round per minute), the open-circuit voltage (V(oc)) remains almost unchanged at approximately 0.

[Study on luminescence characteristics of polymer doped with two different phosphorescent materials].

With the development of organic light-emitting diodes, interests in the mechanisms of charge carrier photo generation, separation, transport and recombination continue to grow. Phosphorescent organic light-emitting diodes have gained considerable interest in the last 10 years because of high luminance efficiency. In the present paper, the authors investigated the optical and electrical characteristics of the devices based on Ir(ppy)3 and Ir(piq)3 doped PVK matrix emission layer at room temperature.

[Preparation and transmissivity of ZnS nanocolumn thin films with glancing angle deposition technology].

Nanocrystalline ZnS thin films were fabricated by glancing angle deposition (GLAD) technology in an electron beam evaporation system. Deposition was carried out in the custom vacuum chamber at a base pressure 3 x 10(-4) Pa, and the deposition rate was fixed at 0.2 nm x s(-1).

[Study on photoluminescence quenching of quantum well structure devices under reverse voltage].

Three organic devices with different quantum well period were fabricated. The potential barrier layer and well layer for electrons were made of N,N'-diphenyl-N,N'-bis(1-napthyl)-1,1'-biphenyl 1-4,4'-diamine(NPB) and 4,4,N,N'-dicarbazolebiphenyl(CBP). The photoluminescence quenching of these three devices under changed reverse voltages were studied.

[Research on the synthesis and luminescence characterization of deepen red emission novel polymer].

A deep red emission polymer (PPV-Q) was synthesized successfully. The photoluminescence, electroluminescence and absorption performance of this polymer were studied in detail. The experimental results show that the polymer has strong absorption in the ultraviolet and blue emission wavelength region.

[Study on luminescence properties of a novel rare earth complex Eu(TTA) (2NH2-phen)3].

A novel rare earth complex Eu(TTA) (2NH2-phen)3 was synthesized. The Eu complex was blended with poly(N-vinylcarbazole) (PVK) in different weight ratios and spin coated into films. The photoluminescence of Eu(TTA) (2NH2-phen)3 was obtained.