水溶胶CdSe纳米复合器件电致发光特性的研究

以巯基乙酸为稳定剂在水相中制备了水溶胶CdSe纳米晶,透射电子显微镜表明了纳米晶的形态和尺寸大小.用表面活性剂将CdSe纳米晶从水相中转移到有机相中,将其与具有空穴传输性能的聚合物PVK互溶在一起作为电致发光器件的发光层,以Alq3作为电子传输层,在发光层与Alq3之间加入了空穴阻挡层BCP制备了多层电致发光器件,研究了不同CdSe/PVK配比下水溶胶CdSe纳米复合器件的电致发光特性,结果发现随着水溶胶CdSe纳米晶在纳米复合物中所占比例的降低,电致发光器件的发光强度有所提高,起亮电压有所降低.     

CuS@PVK复合材料的制备及其光学性能

本文分别以吡啶/水混合溶剂和甲醇为分散体系,聚乙烯吡咯烷酮(PVP)等为表面活性剂,采用分散聚合的方法,首先制备出聚乙烯基咔唑(PVK)纳米球。再通过半导体材料CuS对PVK进行掺杂制备出CuS@PVK复合材料。采用扫描电子显微镜(SEM)、粉末XRD、紫外光谱(UV)、荧光光谱(Fluorescence spectrum)等对其进行表征。结果显示该复合材料降低了纯PVK的荧光性能,有利于空穴的传递,增强了复合物的空穴导电能力。     

用稀土金属Eu的有机配合物Eu(DBM)_2(AA)phen作发光层的有机电致发光薄膜的研究

研究了稀土Eu的有机配合物Eu(DBM ) 2 (AA) phen的光致发光特性。用Eu(DBM) 2 (AA) phen作发光层 ,分别用N ,N 双 (3 甲苯 ) N ,N 二苯联苯胺 (TPD)和聚乙烯基咔唑 (PVK)作空穴传输层研制了有机电致发光薄膜器件 ,研究了它们的电致发光特性     

用稀土金属Eu的有机配合物Eu(DBM)2(AA)phen作发光层的有机电致发光薄膜的研究

研究了稀土Eu的有机配合物Eu(DBM)2(AA)phen的光致发光特性.用Eu(DBM)2(AA)phen作发光层,分别用N,N-双(3-甲苯)-N,N-二苯联苯胺(TPD)和聚乙烯基咔唑(PVK)作空穴传输层研制了有机电致发光薄膜器件,研究了它们的电致发光特性.     

高效单发光层绿色有机发光二极管的制备与性能研究

为了提升绿色有机发光二极管的效率,设计了阶梯能级结构的器件,使得载流子在器件中更有效传输,进而有效减缓了器件效率的衰减。选择热致延迟荧光材料(4s,6s)-2,4,5,6-四(9-氢咔唑-9-基)间苯二腈(4CzIPN)作为发光材料,并将其掺杂到能级匹配的主体材料1,3-二(咔唑-9-基)苯(mCP)中构成发光层,制备了一系列单发光层的绿色有机发光二极管。在发光材料的掺杂浓度为2%(wt,质量分数),发光层的厚度为20nm条件下,制得的器件性能最佳,其启亮电压为3.4V,其最大亮度、电流效率、功率效率和外量子效率分别为20706cd/m~2、50.49cd/A、41.96lm/W和16.7%。在亮度为1000cd/m~2条件下,其电流效率和外量子效率仍然高达34.06cd/A和11.6%。器件显示主峰位于504nm的4CzIPN特征发射,随着掺杂浓度的提升,越来越多的电子和空穴被4CzIPN分子所俘获,导致主体材料mCP的特征发射峰逐渐减弱。     

用稀土金属Eu的有机配合物Eu（DBM）2（AA）phen作发光层的有机电致发光薄膜的研究

研究了稀土Eu的有机配合物Eu(DBM)2(AA)phen的光致光发特性,用Eu(DBM)2(AA)phen作光发层,分别用N,N－双（3－甲苯）－N,N’－二苯联苯胺（TPD）和聚乙烯基咔唑＊PVK）作空穴传输层研制了有机电致发光薄膜器件,研究了它们的电致发光特性。     

PtOEP掺杂Alq3有机发光器件的能量传递

研究了高效磷光染料八乙基卟啉铂(PtOEP)掺杂于主体材料八羟基喹啉铝(Alq3)体系中PtOEP、Alq3之间的能量传输机制.分别以PtOEP掺杂和未掺杂的Alq3膜作为发光层制作有机发光器件(OLED),改变掺杂浓度,检测器件电致发光(EL)光谱的变化.经分析,在5%、10%、20%三种掺杂浓度中,10%掺杂浓度能量传递效果最好.通过对掺杂和未掺杂器件电流密度-电压、亮度-电压数据检测,计算外量子效率,在低电流密度(《7mA/cm2)驱动下掺杂器件外量子效率是未掺杂器件的5倍.     

模板法制备聚乙烯咔唑纳米结构中的浸润转变

采用溶液浸润多孔阳极氧化铝模板(AAO)的方法,在孔径为200nm的AAO模板中制备功能聚合物聚乙烯咔唑(poly(vinyl carbazole),PVK)一维纳米结构.SEM和TEM测试结果表明,2.5%和3.5%(质量分数)的PVK溶液可制得纳米管,其外径约为200nm,管壁厚度分别为30与70nm;而5.0%与10.0%(质量分数)的PVK溶液可制得纳米线,其直径约为200nm.提出了溶液浸润模板法中的完全浸润体系和部分浸润体系以及临界浸润浓度Cw.     

原位光催化聚合制备聚(N-乙烯基咔唑)/TiO_2纳米复合材料及其光催化性能

TiO_2作为光催化剂在工业废水、环境污染物处理等多个领域具有广阔的应用前景,但TiO_2粉末易团聚,主要以悬浮态存在于水溶液中,回收性差,而回收不完全易导致二次污染,这极大限制了其在实际工业化中的应用。本研究通过紫外光照射纳米TiO_2直接催化N-乙烯基咔唑原位聚合反应合成聚(N-乙烯基咔唑)/TiO_2纳米复合材料(PVK/TiO_2),利用NMR、TEM、XRD、FTIR、紫外可见吸收光谱仪、荧光分光光度法等对复合材料进行了性能测试和结构表征。结果表明:纳米TiO_2对N-乙烯基咔唑单体具有很高的光催化活性,在紫外光照射下无需外加光引发剂即可引发单体的聚合反应;经洗涤预处理的纳米TiO_2粒子在复合材料中呈颗粒状且分散均匀;随着TiO_2含量的增加,复合材料荧光淬灭效应明显增强。本工作首次发现PVK在紫外光照条件下对甲基橙具有显著的光催化降解活性,且相比于单独的纳米TiO_2或PVK,PVK/TiO_2复合材料在同等条件下降解甲基橙的性能更优,说明PVK显著提高了TiO_2的光催化降解性能。借助PVK优良的耐热、耐腐蚀、成膜性能以及高力学强度的优势,PVK/TiO_2复合材料可被制成粉状、膜状、纤维状、管状等多种光催化降解器件,具有良好的工业化应用前景。     

TPB3 TSi黄光OLED材料的制备及其性能优化

制备以TPB3TSi为发光材料的黄色发光器件。实验表明,当TPB3TSi薄膜厚度为20nm时,器件的发光谱峰位于580nm,其双层和3层器件的最大亮度分别达到7507.6和1385cd/m2(17V电压下),但是器件的电流较大,造成了器件的发光效率偏低,其原因是TPB3TSi材料本身的电荷陷阱(所谓陷阱指的是拥有比母体更容易接受电子或者空穴的能级的位置)较多,荧光效率低,从而降低了器件的效率。     

Energy transfer and morphology study of a new iridium based cyclometalated phosphorescent complex

This paper reports synthesis and characterization of a new phosphorescent iridium complex namely iridium (III) bis (2-phenylpyridinato–N, C^2′) picolinate [(ppy)₂Irpic]. For its future use in organic light emitting diodes (OLED), we doped the iridium complex into various host materials and carried out a study of energy transfer process through photoluminescence (PL) and photoluminescence excitation (PLE) measurements onto the blended films with different concentrations of (ppy)₂Irpic. The blended films were casted by the spin coating method, as to make the device fabrication process cheaper. The selected host materials were poly(N-vinylcarbazole) (PVK), poly(9,9-dihexylfluorene) (PDHF) and N,N′-diphenyl-bis(3-methylphenyl) [1,1′-biphenyl]-4,4′-diamine (TPD). The blended films with TPD as a host were made in poly(methyl-methacrylate) (PMMA) matrix. The emission from the host molecule disappears at a particular concentration of (ppy)₂Irpic, which is determined as 5 wt%, 12 wt% and 20 wt% of the host materials for blended PVK, TPD (20% by weight of PMMA) and TPD (10% by weight of PMMA) films, respectively. No energy transfer could be observed for PDHF for the concentration range of 0.1–20 wt%. The energy transfer efficiency and the morphology of the various blends were also studied in order to find out the most appropriate host material for the device applications.     

Photo and electroluminescence of a platinum porphyrin doping of complexes with two metal cores

In this paper, four new complexes with two metal cores [2Sm, 2Sn, 2Zn and 2Pb] were prepared and utilized as host material in in the electroluminescence (EL) devices. Devices with two metal cores and with the structure of ITO/PEDOT: PSS (60 nm)/PVK (55 nm)/[2Sm, 2Sn, 2Zn and 2Pb]: %8 [2,5PtTPP] (45 nm)/Al (200 nm) were fabricated, A blue–green photoluminescence (PL) emission with a blue shift compared to the 2,5PtTPP was observed. 2,5PtTPP doped in 2Sm and 2Sn showed more pure red color compared to 2Zn and 2Pb based devices. We believe that energy transfer occurring at 2,5PtTPP/[2Sm, 2Sn] molecules is responsible for the red color in the EL of the device. The electronic effect of two metal cores of complexes influenced the maximum current density, brightness, and luminous efficiency of the devices. Finally, we have demonstrated the samarium complex of 8-hydroxyquinoline is a promising host material for red OLEDs with high efficiency and has a simple device structure.     

Solution processed small molecule-based green phosphorescent organic light-emitting diodes using polymer binder

The authors have demonstrated efficient green organic light-emitting diodes (OLEDs) by using polymer binder. We fabricated small molecular green OLEDs and mixed polymer as a binder such as polystyrene (PS) or poly(N-vinylcarbazole) (PVK). The 4,4'-N,N'-dicarbazole-biphenyl (CBP) is a small molecular material with excellent electrical properties however it become crystalline at high temperature. Polymer binder prevents crystallization of CBP and lead to high efficiency. Therefore, we added PS or PVK into CBP as a polymer binder. As a result, we obtained maximum luminous efficiency, power efficiency and quantum efficiency of 22.8 cd/A, 11.6 Im/W and 6.61% at 23% PS added device.     

Polymer Light-Emitting Diode Using a New Electrophosphorescent Cyclometalated Iridium Complex

A new iridium-based cyclometalated complex, namely bis (2-phenylpyridine-C², N') iridium (III) picolinate [(ppy)₂Ir(pic)] is synthesized and investigated as electrophosphorescent dopant in polymer-based organic light-emitting diodes. The photoluminescence emission from this complex is observed at 501 nm, with a shoulder at 526 nm. Poly(N-vinylcarbazole) (PVK) is used as host polymer and single-layer devices of PVK doped with (ppy)₂Ir(pic) complex are fabricated. Photoluminescence (PL) spectra of PVK films doped with different concentration of iridium complex were measured to study the possible energy transfer occurring between PVK to iridium complex. A predominant blue to a completely green shifted emission is observed when the doping concentration was increased from 0% to 5 wt%. Optical and atomic force microscopic images of the doped films indicate a smooth film formation when spin coated with chlorobenzene as a solvent as compared to chloroform. Electroluminescence spectra of ITO/PEDOT:PSS/PVK:(ppy)₂Ir(pic)/Al device resembles that of the PL spectra with emission at 507 nm and Commission Internationale de l'Eclairage (CIE) coordinates (0.29, 0.57).     

Carbazole functionalized isocyanide brushes in heterojunction photovoltaic devices

In this work, carbazole-containing polyisocyanide (PIACz) brushes were used for photovoltaic devices. A photovoltaic device was fabricated on top of the brushes by spin-coating a suitable acceptor and evaporating an Al cathode. Devices with a poly(N-vinylcarbazole) (PVK) bulk polymer were also prepared for comparison. Interestingly, the brushes showed better photovoltaic characteristics as compared to the blended PVK system. This is attributed to the specific morphologies of the polyisocyanide brushes, which provide a large interfacial area between the donor and acceptor for efficient photogeneration. It was found that the device performance varied according to the molecular size of the incorporated acceptors.     

Flexible Quasi-2D Perovskite/IGZO Phototransistors for Ultrasensitive and Broadband Photodetection

Organic–inorganic hybrid perovskites (PVKs) have recently emerged as attractive materials for photodetectors. However, the poor stability and low electrical conductivity still restrict their practical utilization. Owing to the quantum-well feature of two-dimensional (2D) Ruddlesden–Popper PVKs (2D PVKs), a promising quasi-2D PVK/indium gallium zinc oxide (IGZO) heterostructure phototransistor can be designed. By using a simple ligand-exchange spin-coating method, quasi-2D PVK fabricated on flexible substrates exhibits a desirable type-II energy band alignment, which facilitates effective spatial separation of photoexcited carriers. The device exhibits excellent photoresponsivity values of >10⁵ A W⁻¹ at 457 nm, and broadband photoresponse (457–1064 nm). By operating the device in the depletion regime, the specific detectivity is found to be 5.1 × 10¹⁶ Jones, which is the record high value among all PVK-based photodetectors reported to date. Due to the resistive hopping barrier in the quasi-2D PVK, the device can also work as an optoelectronic memory for near-infrared information storage. More importantly, the easy manufacturing process is highly beneficial, enabling large-scale and uniform quasi-2D PVK/IGZO hybrid films for detector arrays with outstanding ambient and operation stabilities. All these findings demonstrate the device architecture here provides a rational avenue to the design of next-generation flexible photodetectors with unprecedented sensitivity.     

Bisphenol A based pyrazoloquinoline dimers as dopants for electroluminescent applications

A series of 1,3-methyl/phenyl (1,3-Me/Ph) bisphenol A based pyrazoloquinoline dimers (BAPQD) have been synthesized and characterized by spectroscopic methods. The obtained results demonstrate that recently synthesized dyes may be considered as promising materials for electroluminescent applications being used as dopants of PVK layers in OLED fabrication. The electroluminescent devices of the structure (ITO)/PVK:BAPQD-X/Ca/Al (X = 1–4) have been constructed and their current-voltage-luminescence characteristics are derived. In PVK host the 1,3-Me/Ph BAPQD derivatives emit light with different shades of blue color.     

Synthesis of a neodymium-quinolate complex for near-infrared electroluminescence applications

A structurally pure, near-infrared emissive Nd-(5,7-dichloro-8-hydroxyquinoline)₄ tetrakis complex has been synthesized. When incorporated as a dopant in the blue emissive, hole conducting polymer poly(N-vinylcarbazole), PVK, sensitized neodymium ion emission was observed following photo-excitation of the polymer host. OLED devices were fabricated by spin-casting layers of the doped polymer onto glass/indium tin oxide (ITO)/3,4-polyethylene-dioxythiophene-polystyrene sulfonate (PEDOT) substrates. An external quantum efficiency of 1 × 10^− 3% and a near-infrared irradiance of 2.0 nW/mm² at 25 mA/mm² and 20 V was achieved using glass/ITO/PEDOT/ PVK:Nd-(5,7-dichloro-8-hydroxyquinoline)₄/Ca/Al devices.     

High efficiency phosphorescent white organic light-emitting diodes using a spirofluorene based phosphine oxide host material

High efficiency phosphorescent white organic light-emitting diodes (PHWOLEDs) were developed by using a spirofluorene based phosphine oxide (SPPO1) as a host material in blue emitting layer. A stack structure of red:green/blue with an interlayer was used and the device performances of PHWOLEDs were investigated according to host composition in red:green emitting layer and the interlayer thickness. The use of SPPO1 as a host in the blue emitting layer resulted in a high quantum efficiency of 13.5% and a current efficiency of 27.6 cd/A with a color coordinate of (0.37, 0.43).