电压调节变色的有机薄膜电致发光器件

制备了结构为ＩＴＯ／ＳＡ／ＰＢＤ／Ａｌｑ３／Ａｌ的电压调制发光颜色的有机薄膜电致发光器件，研究了有机层厚度不同的器件的发光光谱随电压变化的性能，建立了器件的能级结构模型，并用这种模型解释了器件的电致发光性能。     

PPV／ZnS薄膜器件发光及电导的研究

以Ⅱ－Ⅵ族无机半导体ＺｎＳ替代双层有机薄膜电致发光器件的电子传输层,以ＰＰＶ为空穴传输层和发光层制备发光器件,得到发光亮度和效率都比单层ＰＰＶ器件高的电致发光器件。器件结构为ＩＴＯ／ＰＰＶ／ＺｎＳ／Ａｌ。器件的电致发光光谱同单层ＰＰＶ器件的光说基本相同,但启亮电压只有４．５Ｖ,亮度也比单层器件高一个量级。通过ＰＰＶ层自吸收现象可塑料出发光区域在ＰＰＶ／ＺｎＳ界面处。器件的电流密度与电压的二次方式线     

金刚石薄膜电致发光中的奇异现象

制备了不同结构的金刚石薄膜电致发光器件，研究了其光谱特性和发光特性。结果发现一般结构的样品器件的发光强度和激发电源频率之间存在一极大值， 特殊结构的样品器件的发光强度和激发电压之间存在一极大值的奇异现象，并对这些现象作了解释。     

聚对苯乙炔的EL特性和在双层OTFEL器件中的应用

应用自制的聚对苯乙炔与Ａｌｑ３和Ｚｎｑ２做成单层、双层有机电致发光器件，研究了聚对苯乙炔的电致发光特性和在器件中的作用，发现了一些有意义的新现象，说明它是有机电致发光领域里极其重要的一种功能材料。     

聚合物电致发光材料的研究现状及应用前景

聚合物电致发光材料是近几年来取得很大进展而倍受关注的新型功能材料。电致发光薄膜器件激发电压低、发光效率高、易得到彩色显示 ,而且容易实现大屏幕平板化。本文综述这类薄膜电致发光器件的发光原理、发光材料、器件的制备方法以及改善器件特性的方法     

聚对苯乙炔的EL特性和双层OTFEL器件中的应用

应用自制的聚对苯乙炔与Ａｌｑ３和Ｚｎｑ２做成单层、双层有机电致发光器件，研究了聚对苯乙炔的电致发光特性和在器件中的作用，发现了一些有意义的新现象，说明它是有机电致发光领域里极其重要的一种功能材料。     

含Eu^3＋红色窄带发射的电压变色的有机电致发光

本文研究了含有稀土有机配合物的有机电致发光（ＯＥＬ）器件，这种器件在改变驱动电压时可获得不同的ＯＥＬ发射颜色，其中红色分类自Ｅｕ（１１１）离子的特征发射，在正向偏压的１０，１５和２０Ｖ时可分别获得红，绿和黄色的ＯＥＬ发射。     

含Eu~(3+)红色窄带发射的电压变色有机电致发光

本文研究了含有稀土有机配合物的有机电致发光（ＯＥＬ）器件。这种器件在改变驱动电压时可获得不同的ＯＥＬ发射颜色，其中红色成分来自Ｅｕ（１１１）离子的特征发射。在正向偏压为１０，１５和２０Ｖ时可分别获得红，绿和黄色的ＯＥＬ发射。     

金属／YSZ多晶陶瓷电极交流阻抗特性

本文测量了以Ｙ２Ｏ３稳定的ＺｒＯ２（ＹＳＺ）电池：Ａｉｒ，Ｍ（ｐｔ、Ａｕ、Ｐｄ－Ａｇ）｜ＹＳＺ）｜Ｍ（ｐｔ、Ａｕ、Ｐｄ－Ａｇ），Ａｉｒ在２５０～５００°Ｃ、１２Ｈｚ～１００ＫＨｚ之间的交流阻抗．从作出阻抗谱分析，计算了ＹＳＺ多品陶瓷的晶内、晶界电阻及其对温度的依从性．晶界阻抗半圆的特征频率和温度的关系同样服从于Ａｒｒｈｅｎｉｕｓ公式．比较了Ｐｔ、Ａｕ和Ｐｄ－Ａｇ电极在ＹＳＺ氧化物电解质上的极化特性，并对氧通过各个电极扩散的电极过程中氧浓度－扩散率的积ＣＯ作了计算．     

分层优化薄膜电致发光器件预热层的研究

在本文的工作中，我们比较了以ＳｉＯ２／Ｙ２Ｏ３和ＳｉＯ２／Ｔａ２Ｏ５为复合预热层及以ＳｉＯ为预热层的电致发光器件的发光亮度和传导电流，我们发现ＳｉＯ作为预热层的器件发光亮度优于其它两种器件。利用数值模拟的方法，推导出热电子能量，结果表明，ＳｉＯ为预热层的电致发光器件的热电子能量也明显高于另外两种器件。     

Flexible top-emitting organic light-emitting diodes using semi-transparent multi-metal layers

In this paper, the improved device performance of top-emitting organic light-emitting diodes (TEOLEDs) with a thin multi-metal layer stack of nickel/silver/nickel (Ni/Ag/Ni) and aluminum/silver/aluminum (Al/Ag/Al) that were used as the anode and cathode on a flexible substrate is discussed. In particular, Indium-Tin-Oxide (ITO) as an anode electrode has been used recently even though it has some problems for flexible devices. Therefore we suggested that a thin multi-metal layer electrode as a new anode is fabricated instead of ITO anode. It was verified that the ITO-free TEOLEDs showed an enhanced probability of the recombination of the electrons and holes through an improved electron/hole charge balance. We also analyzed the optical and electrical characteristics using the current density, luminance, luminance efficiency, external quantum efficiency (EQE), CIE x, y coordinates, and EL spectra of flexible TEOLED devices were characterized. ITO-free, flexible, green-emitting OLEDs with a low cost and a simple process were demonstrated.     

Improving efficiency of organic light-emitting diodes fabricated utilizing AZO/Ag/AZO multilayer electrode

Multilayer transparent electrode based on Al-doped zinc oxide (AZO)/Ag/Al-doped zinc oxide (AZO) was fabricated by sputtering, and a green organic light-emitting diode (OLED) device utilizing AZO/Ag/AZO as anode was fabricated. The AZO/Ag/AZO multilayer film exhibited superior square resistance and optical transmittance to those of commercial indium tin oxide (ITO). In comparison with the green OLEDs based on ITO and pure AZO anode, the green OLED based on AZO/Ag/AZO showed the highest light-emitting efficiency. The results indicate that AZO/Ag/AZO multilayer electrodes are a promising low-cost, low-toxic and low-temperature processing electrode scheme for OLED application.     

N_2O等离子体处理对富硅氮化硅薄膜发光的影响

采用PECVD方法制备富硅氮化硅(SiNx)薄膜,并研究了N2O等离子体处理对SiNx薄膜光致发光(PL)及电致发光(EL)的影响。研究结果表明,N2O等离子体处理前后SiNx薄膜的PL发光峰均位于430nm处,且强度变化不大。而其EL发光峰位于600nm处,处理后强度有所提高。但经过高温热处理后,EL强度会大幅度降低。这主要是由于N2O等离子体处理在薄膜中引入N原子,这些N原子与Si原子结合,消除Si的悬挂键,降低了非辐射复合中心的浓度;而热处理后发生的原子重排,使得N原子与Si原子断开,进而与O原子结合,致使EL强度降低。     

Enhancement of green electroluminescence from 2,5-di-p-anisyl-isobenzofuran by double-layer doping strategy

A highly fluorescent compound, 2,5-di-p-anisyl-isobenzofuran (DABF), was synthesized and used as a dopant to fabricate efficient green electroluminescence (EL) devices. The highest occupied molecular orbital level of DABF suggests that it can be excited either by energy transfer or by direct charge trapping mechanism in the EL devices. Three kinds of devices were fabricated based on different emission mechanisms. A double-layer-doped device with DABF doped in both the hole-transporting layer and the electron-transporting layer of the ITO/NPB/TPBI/Mg:Ag device, where ITO is indium-tin-oxide, NPB is (4,4′-bis[N-(1-naphthyl)-N-phenylamino]biphenyl), and TPBI is (2,2′,2″-(1,3,5-benzenetriyl)tris[1-phenyl-1H-benzimidazole]), exhibited greatly enhanced brightness and efficiency comparing to the single-layer-doped devices. The brightness and efficiency enhancements are attributed to a combined contribution of energy transfer and direct charge trapping mechanisms in the double-layer-doped device.     

Laser-induced forward transfer of polymer light-emitting diode pixels with increased charge injection

Laser-induced forward transfer (LIFT) has been used to print 0.6 mm × 0.5 mm polymer light-emitting diode (PLED) pixels with poly[2-methoxy, 5-(2-ethylhexyloxy)-1,4-phenylene vinylene] (MEH-PPV) as the light-emitting polymer. The donor substrate used in the LIFT process is covered by a sacrificial triazene polymer (TP) release layer on top of which the aluminium cathode and functional MEH-PPV layers are deposited. To enhance electron injection into the MEH-PPV layer, a thin poly(ethylene oxide) (PEO) layer on the Al cathode or a blend of MEH-PPV and PEO was used. These donor substrates have been transferred onto both plain indium tin oxide (ITO) and bilayer ITO/PEDOT:PSS (poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate) blend) receiver substrates to create the PLED pixels. For comparison, devices were fabricated in a conventional manner on ITO substrates coated with a PEDOT:PSS hole-transporting layer. Compared to multilayer devices without PEO, devices with ITO/PEDOT:PSS/MEH-PPV:PEO blend/Al architecture show a 100 fold increase of luminous efficiency (LE) reaching a maximum of 0.45 cd/A for the blend at a brightness of 400 cd/m(2). A similar increase is obtained for the polymer light-emitting diode (PLED) pixels deposited by the LIFT process, although the maximum luminous efficiency only reaches 0.05 cd/A for MEH-PPV:PEO blend, which we have attributed to the fact that LIFT transfer was carried out in an ambient atmosphere. For all devices, we confirm a strong increase in device performance and stability when using a PEDOT:PSS film on the ITO anode. For PLEDs produced by LIFT, we show that a 25 nm thick PEDOT:PSS layer on the ITO receiver substrate considerably reduces the laser fluence required for pixel transfer from 250 mJ/cm(2) without the layer to only 80 mJ/cm(2) with the layer.     

Solution-processed flexible polymer solar cells with silver nanowire electrodes

The conventional anode for organic photovoltaics (OPVs), indium tin oxide (ITO), is expensive and brittle, and thus is not suitable for use in roll-to-roll manufacturing of OPVs. In this study, fully solution-processed polymer bulk heterojunction (BHJ) solar cells with anodes made from silver nanowires (Ag NWs) have been successfully fabricated with a configuration of Ag NWs/poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS)/polymer:phenyl-C(61)-butyric acid methyl ester (PCBM)/Ca/Al. Efficiencies of 2.8 and 2.5% are obtained for devices with Ag NW network on glass and on poly(ethylene terephthalate) (PET), respectively. The efficiency of the devices is limited by the low work function of the Ag NWs/PEDOT:PSS film and the non-ideal ohmic contact between the Ag NW anode and the active layer. Compared with devices based on the ITO anode, the open-circuit voltage (V(oc)) of solar cells based on the Ag NW anode is lower by ~0.3 V. More importantly, highly flexible BHJ solar cells have been firstly fabricated on Ag NWs/PET anode with recoverable efficiency of 2.5% under large deformation up to 120°. This study indicates that, with improved engineering of the nanowires/polymer interface, Ag NW electrodes can serve as a low-cost, flexible alternative to ITO, and thereby improve the economic viability and mechanical stability of OPVs.     

To increase the lifetime of electroluminescent (EL) device by low-temperature deposition of organic thin solid films

We have studied the electrical and light-emitting behaviour as well as the lifetime of electroluminescent (EL) cells which consist of naphthoylimide (NPL) as the emitting layer and poly(3-octythiophene) (P3OT) doped with poly(N-vinylcarbazoe) (PVK) as the hole transport layer sandwiched between indium-tin-oxide (ITO) and aluminium (Al) electrodes. The mixed polymer (P3OT : PVK) layer and the emitting layer were deposited by spin coating and by vacuum deposition. When the ITO substrate was cooled to near liquid N2 temperature during the deposition of the NPL emitting layer, the brightness of the cells increased. Characterized by atomic force microscopy (AFM), the emitting layer became more amorphous as the deposition temperature decreased. Results collected show that low temperature deposition of organic thin solid films would be a powerful technique for not only the enhancement of electroluminescent brightness but also increasing the lifetime of EL devices. © 1998 Kluwer Academic Publishers     

Improved performance of the single-layer and double-layer organic light emitting diodes by nickel oxide coated indium tin oxide anode

The electrical and optical properties of the NiO films deposited under various conditions were first characterized. An ultra-thin layer of nickel oxide (NiO) was then deposited on the indium-tin oxide (ITO) anode to enhance the hole injection in the organic light-emitting diode (OLED) devices. A very low turn-on voltage (3 V) was actually observed for the device with the ITO/NiO anode in the conventional double layer heterojunction OLEDs. The enhancement of hole injection by the ITO/NiO anode was further verified by the hole-only device and by the device with a patterned NiO layer on the ITO anode. The luminance and the current density of the single-layer OLED device were also significantly improved by using the ITO/NiO anode to enhance the hole injection. Although the luminescence efficiency was low, the reasons of low efficiency were studied and the improvement method was proposed. Our results suggest that the NiO/ITO anode is an excellent choice to enhance the hole injection in OLED devices.     

Fabrication and characterization of organic light-emitting diodes using zinc complexes as hole-blocking layer

2-(2-Hydroxyphenyl)benzoxazole (HPB) was employed as organic ligand and the corresponding zinc complexes (Zn(HPB)2 and Zn(HPB)q) were synthesized. And their EL properties were characterized. The structures of zinc complexes were determined with FT-NMR, FT-IR, UV-Vis, and XPS. The thermal stability showed up to about 300 degrees C under nitrogen flow, which was measured by TGA. The photoluminescence (PL) of zinc complexes were measured from the DMF solution. The PL emitted in blue and yellow region, respectively. The EL devices were fabricated by the vacuum deposition. Two kinds of OLEDs devices were fabricated; ITO/NPB (40 nm)/Zn complexes (60 nm)/LiF/Al and ITO/NPB (40 nm)/Alq3 (60 nm)/Zn complexes (5 nm)/LiF/Al. Both of the EL properties as the emitting and the hole-blocking layer were investigated. The EL emission of Zn(HPB)q exhibited green light centered at 532 nm. The device showed a turn-on voltage at 5 V and a luminance of 6073 cd/m2 at 10 V. Meanwhile, the maximum EL the emission of the Zn(HPB)2 device was found to be at 447 nm. And the device showed a luminance of 2813 cd/m2 at 10 V. The ITO/NPB (40 nm)/Alq3 (60 nm)/Zn(HPB)2 (5 nm)/LiF/Al device showed increased luminance of L=17000 cd/m2 compared to L=12000 cd/m2 for similar device fabricated without the hole-blocking layer. And the turn-on voltage was significantly affected by the existence of the hole-blocking layer.     

Polymer light-emitting devices based on plasma-polymerized benzene and plasma-polymerized naphthalene

Polymer light-emitting devices (PLED) were fabricated utilizing plasma-polymerized benzene (PPB) and plasma-polymerized naphthalene (PPN) as an electroluminescent (EL) emitting layer. The plasma polymerization is well suited for forming the transparent, sturdy thin film for EL polymer layers. For the ITO/PPB/Al and ITO/PPN/Al devices, the turn-on voltage of the device was at 12V and 6V, respectively. The luminance of the PPB device reached 6 cdm ^-2 at 10 V, whereas the PPN device reached 11 cd m ^-2 at 14 V. The external quantum efficency was 0.0035% for the PPB device and 0.0056% for the PPN device. The dense crosslinked structure formed by the plasma polymerization makes the EL device relatively stable during operation. © 2001 Kluwer Academic Publishers