Efficient and Low-voltage Phosphorescent Organic Light-emitting Devices Based on Blue Iridium Complex Host

By adopting a phosphorescent host/guest system consisting of blue iridium complex as host and a series of phosphorescent dyes as guest, efficient and low-voltage monochromic organic light-emitting devices(OLEDs) were fabricated. The devices with blue iridium host have higher power efficiency than the device with the conventional host 4,4'-N,N'-dicarbazole-biphenyl. The enhancement of the maximum power efficiency in green phosphorescent device can reach 37.2%. Dichromatic white OLED could be achieved by simply adjusting the concentration of the orange dyes. At a brightness of 1000 cd/m², the power efficiency of the white device is 8.4 lm/W with a color rendering index of 76.     

Structural Controls of Tetraphenylbenzene-based AIEgens for Non-doped Deep Blue Organic Light-emitting Diodes

Aggregation-induced emission(AIE)has emerged as a new concept,giving highly efficient solid-state photoluminescence.Particularly,AIE luminogens(AIEgens)with deep blue emission(400–450 nm)have displayed salient advantages for non-doped organic light-emitting diodes(OLEDs).However,deep blue emitters with Commission Internationale de L’Eclairage(CIE)coordinates less than 0.08 are still rare.In this review,we outline the latest achievements in the molecular guidelines based on the AIE core of tetraphenylbenzene(TPB)for developing efficient deep blue AIEgens.We provide insights into the construction of deep blue emitters with high horizontal orientation by regulating the length of the linear molecule.We also discuss the luminescence mechanisms of these AIEgens-based OLEDs by using the magnetic field effects measurements.Finally,a summary of the challenges and perspectives of deep blue AIEgens for non-doped OLEDs is also presented.     

Hermetic Seal of Organic Light Emitting Diode with Glass Frit

The components of OLED encapsulation with hermetic sealing and a 1026-day lifetime were measured by PXI-1033. The optimal characteristics were obtained when the thickness of the TPBi layer was 20 nm. This OLED obtained a maximum luminance (Lmax) of 25,849 cd/m² at a current density of 1242 mA/cm², an external quantum efficiency (EQE) of 2.28%, a current efficiency (CE) of 7.20 cd/A, and a power efficiency (PE) of 5.28 lm/W. The efficiency was enhanced by Lmax 17.2%/EQE 0.89%/CE 42.1%/PE 41.9%. The CIE coordinates of 0.32, 0.54 were all green OLED elements with wavelengths of 532 nm. The shear strain and leakage test gave results of 16 kgf and 8.92 × 10⁻⁹ mbar/s, respectively. The reliability test showed that the standard of MIL-STD-883 was obtained.     

小分子有机电致发光器件和材料的研究及应用

有机电致发光器件(OLED)是在电场作用下,以有机材料为活性发光层的器件.由于OLED具有亮度高、响应快、视角宽、工艺简单、可柔性等优点,在现代科学研究及技术应用中备受关注.其商业化应用,诸如平板显示(FPD)和固体照明(SSL)等,正在不断向前推进.本文综述了小分子OLED的各种器件结构和功能材料研究进展以及该领域存...     

Influence of Electrical,Chemical and Morphological Properties of Inorganic/Organic Interface on Light Emitting Devices Performance

studies on the influence of chemical and physical treatments on the properties of indium–tin oxide (ITO) thin films are reported. The ITO films are utilized as transparent anodes of organic light-emitting diodes (OLEDs) incorporating poly(9,9-dihexyl-9H-fluorene-2,7-diyl) (PF6) as the hole transporter material and 8-hydroxyquinoline aluminum salt (Alq3) as emitter material. Chemical (HCl, piranha solutions), thermal (vacuum annealing), physical treatments (oxygen plasma, UV ozone) and combined treatments are studied. First, ITO layers with different treatments are characterized by using four point probe method, contact angle measurement, X-Ray diffraction (XRD), surface profilometer, scanning electron microscopy (SEM), UV-Vis-IR transmittance. Later, electrical and optical properties of OLEDs with treated ITO as anode are extensively investigated.     

有机电致发光器件的界面问题研究进展

低驱动电压下有机电致发光器件(0ELD)中的界面结构对器件效率和寿命有重要影响。本文简要介绍近年来以多种分析技术和方法研究0ELD界面分子结构、能带结构、激发态特性及反应等获得的主要结果,并提出了目前该领域存在的一些问题及发展趋势。     

氧化铟锡(ITO)自组装修饰及其对有机电致发光器件性能的影响

设计合成了一种新型的有机硅氧烷Cz-Si,并将其用于ITO自组装修饰。制备的Cz-Si具有较好的稳定性,可以在空气中对ITO进行自组装修饰,实验操作简单。为考察ITO自组装修饰对有机电致发光器件性能的影响,分别以修饰后的ITO(ITO/SAM)及不修饰的ITO(unmodified)作阳极,制备了一系列有机电致发光器件ITO/SAM(orunmodified)/NPB(40~50nm)/Alq₃(60nm)/LiF(1.0nm)/Al。实验结果表明,ITO自组装修饰后器件性能可以得到显著提升,研究认为这与其调控ITO/有机层界面的电子能级、粗糙度以及界面一致性有关。     

氧化铟锡(ITO)自组装修饰及其对有机电致发光器件性能的影响

设计合成了一种新型的有机硅氧烷Cz-Si,并将其用于ITO自组装修饰。制备的Cz-Si具有较好的稳定性,可以在空气中对ITO进行自组装修饰,实验操作简单。为考察ITO自组装修饰对有机电致发光器件性能的影响,分别以修饰后的ITO(ITO/SAM)及不修饰的ITO(unmodified)作阳极,制备了一系列有机电致发光器件ITO/SAM(or unmodified)/NPB(40~50 nm)/Alq₃(60 nm)/LiF(1.0 nm)/Al。实验结果表明,ITO自组装修饰后器件性能可以得到显著提升,研究认为这与其调控ITO/有机层界面的电子能级、粗糙度以及界面一致性有关。     

Photopatterning of Crosslinkable Hole‐Conducting Materials for Application in Organic Light‐Emitting Devices

Summary: Modern multilayer organic light‐emitting devices (OLED) are fabricated easily and at low cost by spin‐coating with subsequent crosslinking of the layers. For this purpose, a low‐molecular‐weight hole‐transport material based on triphenyl amines bearing crosslinkable oxetane groups was synthesized. Crosslinking of the spin‐coated layer was initiated with UV irradiation using an iodonium‐salt photoinitiator and was observed using realtime FT‐IR spectroscopy. Standard photolithography techniques can be used for structuring the material on the micrometre scale.

An AFM image of the photopatterned bis‐oxetane‐functionalized low‐molecular‐weight hole‐transport material based on triphenyl amines synthesized here.     

Synthesis and characterization of N-carbazole end-capped oligofluorene-thiophenes

A series of novel N-carbazole end-capped oligofluorene-thiophenes with one, two, three, and four thiophene rings were synthesized using either palladium catalyzed cross-coupling reaction or nickel-catalyzed reductive dimerization. All the oligomers have been characterized by ¹H, ¹³C NMR, FTIR, UV-vis, PL spectroscopy and mass spectrometry. It has been demonstrated that the optical, thermal, and electrochemical properties of these materials can be tuned by varying the conjugation length of the oligothiophene segment. The terminal carbazole and fluorene moieties of the resulting materials are beneficial for their morphology, conjugation length, and solubility. These bright fluorescent, thermally and electrochemically stable compounds have potential applications as light-emitting and hole-transporting layers in organic light-emitting devices.     

Effects of MEH-PPV Molecular Ordering in the Emitting Layer on the Luminescence Efficiency of Organic Light-Emitting Diodes

We investigated the effects of molecular ordering on the electro-optical characteristics of organic light-emitting diodes (OLEDs) with an emission layer (EML) of poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV). The EML was fabricated by a solution process which can make molecules ordered. The performance of the OLED devices with the molecular ordering method was compared to that obtained through fabrication by a conventional spin coating method. The turn-on voltage and the luminance of the conventional OLEDs were 5 V and 34.75 cd/m², whereas those of the proposed OLEDs were 4.5 V and 120.3 cd/m², respectively. The underlying mechanism of the higher efficiency with ordered molecules was observed by analyzing the properties of the EML layer using AFM, SE, XRD, and an LCR meter. We confirmed that the electrical properties of the organic thin film can be improved by controlling the molecular ordering of the EML, which plays an important role in the electrical characteristics of the OLED.     

Progress in next-generation organic electroluminescent materials: material design beyond exciton statistics

Exciton (or spin) statistics is a physical principle based on the statistics of spin multiplicity. In electroluminescence, injected electrons and holes have randomized spin states, and usually form singlet or triplet excitons in the ratio of 1:3. Exciton statistics determines that the upper limit of internal quantum efficiency is 25% in fluorescent devices, since only singlet exciton can decay radiatively. However, both experimental and theoretical evidence indicate that the actual efficiency can exceed the exciton statistics limit of 25% by utilizing materials with special electronic structure and optimized device structures. These results bring light to break through the exciton statistics limit and develop new-generation fluorescent materials with low cost and high efficiency. Recently, the exciton statistics, which has attracted great attention in the past decade, is being rejuvenated due to the discovery of some fluorescent materials with abnormally high efficiencies. In view of their significance in theoretical research of organic semiconductors and developing new-generation OLED materials, such materials are widely investigated in both academic institutions and industry. Several key issues still require further clarification for this kind of materials, such as the molecular design concepts. Herein, we review the progress of the materials with efficiency exceeding the exciton statistics limit, and the routes to improve exciton utilization efficiency. In the end, we present an innovative pathway to fully harvest the excitons in fluorescent devices, namely, “hot exciton” model and relevant fluorescence material with hybridized local and charge-transfer (HLCT) excited state.     

基于N-乙基咔唑-2-乙烯基-8-羟基喹啉锌的黄绿色有机电致发光器件的性能

通过用一种既具有空穴传输特性又具有发光特性的新型荧光染料N-乙基咔唑-2-乙烯基-8-羟基喹啉锌((E)-2-(2-(9-ethyl-9H-carbazol-3-yl)vinyl) quinolato-zinc, CzHQZn)作为受主, 制备了结构为ITO/2T-NATA (30 nm)/CBP: 6%Ir(ppy)3:wCzHQZn(20 nm)/Alq3(50 nm)/LiF/Al(ITO: indium-tin oxide, 2T-NATA: 4,4',4'-{N,N-(2-naphthyl)-N-phenylamino}-triphenylamine, CBP: 4,4-N,N'-dicarbazole-biphenyl, Ir(ppy)3: factris (2-phenylpyridine) iridium, Alq3: tris(8-quinolinolato) aluminum; w 是CzHQZn 的质量分数)的黄绿色有机电致发光器件(OLEDs). 研究了掺杂体系在不同掺杂浓度(w=5%、10%、12%、15%)时的电致发光(EL)特性. 结果表明, CzHQZn 掺杂浓度为10%的器件在11 V 电压下实现了黄绿光发射, 色坐标为(0.4045, 0.5113), 最大发光亮度为16110 cd·m-2; 而在7 V电压下的最大发光效率为2.19 cd·A-1, 最大外量子效率为0.775%.     

Synthesis and blue light-emitting properties of 4,4''''-bis(diphenylamino)-quinque(p-phenyl)s

An excellent organic blue light-emitting diode based on 4,40-bis(diphenylamino)-quinque( p-phenylene)s (OPP(5)-NPh) with a maximum luminance of up to 5000 cd/m2 and a luminanous efficiency of 1.3 cd/A was reported. This diode was made by using a wide band-gap hole-blocking layer, F-TBB instead of PBD in the OLED devices. We attribute the good performance to the one trade-off involved in the use of F-TBB to obtain higher luminance is the increased turn-on voltages and slightly decreased device efficiencies.     

A Series of Pure Orange-yellow Iridium Complexes with Low Efficiency Roll-off: a Computational Study

The electronic structures and spectroscopic properties of heteroleptic cyclometalated iridium(III) complexes were investigated. The geometries, electronic structures, and the lowest-lying excited states of (DBQ)₂Ir(acac) and (MDQ)₂Ir(acac) were investigated via density functional theory-based approaches. A series of designed models of (DBQ)₂Ir(dpis), (DBQ)₂Ir(tpip), (MDQ)₂Ir(dpis) and (MDQ)₂Ir(tpip) was also calculated for comparison. The structures in the ground and excited states were optimized via B3LYP method. The lowest absorptions and emissions spectra were evaluated via TD-B3LYP and TD-PBE1PBE methods. The computational results reveal that the emission peaks of the designed complexes are at around 585-640 nm, which belong to the orange-yellow wavelength. The frontier molecular orbital properties indicate that the Ir(III) complexes have low efficiency roll-off.     

多芳基取代咪唑的合成及其逆转多药耐药性研究

合成了一系列新的多芳基取代咪唑类化合物,其结构经元素分析、IR、¹HNMR和MS等确定,并采用MTT法测定了它们对由P-糖蛋白(P-gp)介导的肿瘤多药耐药性(MDR)的逆转效果.结果表明,化合物和具有很好的体外逆转MDR活性     

Electronic Structure Effect of Polythiophene Derivatives and Nano N-Zn-Ag/TiO2 on Performance of Organic Thin Film Solar Cell

Nanocrystal N-Zn-Ag/TiO₂ powders were prepared with N-Zn/TiO₂ by photo deposition method. A series of pure polymers P3HT[poly(3-hexylthiophene)], P3OT[poly(3-octylthiophene)], P3DT[poly(3-decylthiophene)] and P3DDT[poly(3-dodecylthiophene)], was synthesized, which were used to synthesize p-n type semiconductor materials P3HT/N-Zn-Ag-TiO₂, P3OT/N-Zn-Ag-TiO₂, P3DT/N-Zn-Ag-TiO₂ and P3DDT/N-Zn-Ag-TiO₂ by in situ che-mical method. X-Ray diffraction(XRD) and infrared(IR) spectroscopy showed the structure of the polymers and complexes. Ultraviolet-visible(UV-Vis) spectra and cyclic voltammograms(CV) showed the optical and electronic performance of the polymers and complexes. Two new single and double organic thin film heterojunction solar cells were prepared with the above mentioned synthesized powders as raw materials. Current-voltage(I-V) measurements indicate that the conversion efficiency of the single organic thin film heterojunction solar cell is higher than that of the double organic thin film heterojunction solar cells. Single organic thin film heterojunction solar cells based on P3DT/N-Zn-Ag-TiO₂ can get a photoelectric conversion efficiency of 0.0408%. The performance of electronic transform between electron donor and acceptor on organic thin film solar cells was researched.     

果菠萝蛋白酶在有机溶剂微扰时的分子折叠与活力变化的研究

本文用荧光、紫外差示及CD光谱研究果菠萝蛋白酶经甲醇、乙醇、乙二醇微扰后的构象与活力变化情况.酶的荧光强度随有机溶剂浓度增大而增强,表明Tyr、Trp微环境发生明显变化。232nm和285nm处出现紫外差吸收正峰。前峰与酶分于折叠的变化有关,而后峰与Tyr、Trp微环境的变化相关.甲醇、乙醇微扰后,天然酶的208nm和225nmCD双负峰逐渐加强,而乙二醇微扰后,225nm负峰加强。208nm负峰减弱并红移直至完全消失,说明酶分子完全伸展.     

涡旋辅助分散液液微萃取-悬浮固化/高效液相色谱法测定水样中7种萘二酚

建立了水样中7种萘二酚的涡旋辅助分散液液微萃取-悬浮固化/高效液相色谱(VA-DLLMESFO/HPLC)测定方法。以乙醚-十二醇为二元微萃取剂,通过涡旋分散方式协同萃取水样中的目标化合物,采用C18色谱柱分离,HPLC测定。优化了萃取剂及用量、萃取时间、氯化钠用量等条件。最佳萃取条件为:萃取剂为100μL乙醚和50μL十二醇,氯化钠用量为0.2 g/m L,涡旋萃取3 min。在优化条件下,7种萘二酚在一定质量浓度范围内线性关系良好,相关系数均大于0.997,方法检出限(S/N=3)为1.7~6.0μg/L;3个加标水平下的平均回收率为82.1%~106.0%,日内相对标准偏差(RSD,n=5)为1.2%~4.1%;中间添加水平的日间RSD(n=5)为2.5%~5.7%。该方法前处理简单,涡旋分散大大提高了物质传质速率,增大了萃取效率,缩短了萃取时间,是一种适用于水样中萘二酚类物质富集检测的绿色方法。