OLED外文文献翻译

1、文档来源为 :从网络收集整理.word 版本可编辑.欢迎下载支持ITO表面经过常压等离子体处理的有机发光器件的特性Chang Hyun JEONG, June Hee LEE, Yong Hyuk LEE, Nam Gil CHO, Jong Tae LIM,Cheol Hee MOON and Geun Young YOMEDepartment of Materials Science & Engineering, Sungkyunkwan University, Suwon, 440-746, KoreaPDP Division, Samsung SDI Co., Ltd., Ch

2、eonan, 330-300, Korea(Received October 4, 2004; accepted October 28, 2004; published December 10, 2004)摘要：本课题研究了 ITO表面经过He/Q和He/SF6的常压等离子混合气体处理后的影响和有机发光器件的电学特性。经过He/Q或He/SF6的等离子体处理后，由ITO/2-TNATA/NPD/Alq3/LiF/Al组成的OLED器件显示出了很好的电学特性，例如：较低的导通电压，高的功率效率等等。经过He/SF6 处理的器件与He/O2处理过的相比有更卓越的电学性能。在用He/O2和He/SN

3、等离子体处理后，改善后的电性能与碳元素的减少和ITO表面Sn4+的聚集以及ITO中氟元素的掺杂浓度有关，这表明表面处理后工作性能 有所提高。关键词：ITO,表面处理，常压等离子体，OLED He/Q, He/SF6OLE况示器件之所以能得到广泛的研究是因为他们具有非常优越的特性，例如：快速的响应时间，较低的工作电压，较高的量子效率等等。此外，与其他的平板显示器相比，例如：液晶显示器和等离子显示器，OLEDB示器有更简单的工艺流程和更低的制造成本。目前，对于基板尺寸小于370mm*470mm的器件，通常在一个真空腔体内利用多层蒸发技术来完成，而用于制造接近920mm*730mmJ大尺寸的沉积技术

4、目前正处于研发当中。此外，利用喷墨打印技术代替真空蒸发技术来制作高分子有机OLED器件正处于积极的研发阶段。对于OLE端件，需要一种透光性高的透明导体，在各种透明导体中，具有高传导性和高透光性的ITO被广泛的应用。为形成 OLE端件，有机材料被沉积在ITO上，形成一个低阻值的欧姆接触，OLED器件在 ITO 和有机材料之间形成的接触电阻可以通过 ITO 表面预处理来改变。 ITO 是一个非化学计量 化合物，化学成分可以很容易的改变。因此，为了改善OLE端件中ITO和有机材料间的接触特性，在ITO表面沉积有机材料之前进行处理是非常重要的。作为表面处理方法的低压等离子技术、UV/O技术、和湿处理均

5、被用于去除有机杂质和改善ITO表面特性。然而，这些技术价格非常昂贵，而且低压等离子技术和UV/O3 技术难以用于规模较大的基板，并且，湿处理法还存在环境问题。为了代替低压等离子体技术和湿处理等技术，以常压等离子体，如电晕放电、电介质阻挡放电、大气等离子流体等为处理技术来处理电子材料、电极材料、生物材料和结构材料的方法正在积极地开发当中。本课题研究了利用常压等离子体来处理和清洁 OLEDITO玻璃表面的价值。作为常压等离 子清洁技术，即一个修改了的 DB/术，能被用于大规模的环境中并且展现了一个比传统DBEM高密度的等离子体。通过改变在修改的 DBD昆合气体，这些混合气体在ITO的表面特性和形成

6、干净的ITO 玻璃的OLE端件电学特性方面的影响正在观察中。图1为处理ITO玻璃表面的常压等离子体设备图。如图所示，修改过的DBD勺研究设备由代替一个平板电极作为功率电极的锥体形状的多针电极，作为接地端的另一块平板电极以及两电极间的电介质材料组成。使用多针电极代替平板电极，通过在针的尖端形成一个类似于具有较高稳定性的电晕放1文档来源为：从网络收集整理.word版本可编辑.欢迎下载支持电和辉光放电的高电场，从而能够获得一个高的离子体密度和低压交流下的气体击穿。多针功率电极连接到频率为2030千赫兹、电压 为315千伏的交流电压，平板接地 电极接地。He(10 slm)/O2(3 slm)和 He

7、(10 slm)/SF 6(100 sccm)的混合 气体被应用于OLEDITO表面的 清洗。在等离子处理前，所有的ITO 玻璃均用有机溶剂清洗过。这些气 体的最佳成分通过接触角和ITO基 板碳含量来选择，接触角利用专用 工具来测量，碳含量通过改变由 03 slm 的氧流速、0500 sccm 的 SF6流速以及10slm的氨流速的X 射线光电谱线来测量。交流电源为 25千赫兹、10千伏，持续工作30'wwvwww'Mulli-plii powerdtdrodtrro3立G1向Fip 1. Schciikitic di与ram of the aimosplicnL preure

8、 pLnia cquipincm usM for the surface treamiiMH ct 11U glass.4秒。经过He/Q和He/SF6等离子混合气体清洁后的ITO表面组成用X射线源为1486.6 eV的X射线光 电子能谱来研究。在没有破坏真空的条件下，通过在洁净的ITO上OLE附料的热分解和电极材料的顺序蒸镀制备成了 OLED件。研究的这个 OLE邮件的Z勾为 ITO/2-TNATA(60 nm)/NPD(20 nm)/Alq 3(40 nm)/LiF(1nm)/Al(100 nm)。有机材料、氟化锂和铝的沉积速率分别为0.3 -0.5 A/s、0.1 A/s、0.5 -5

9、A/s ,器件的有效面积为 4mmi OLED器件的电学特性由电子仪器测量得到，光学特性通过使用皮安计测量 OLE湍件光发射引起的光电流来得到。图2所示为ITO经过He(10 slm)/O 2(3 slm) 和He(10 slm)/SF 6(100 sccm)常压等离子混合气体 处理的OLE端件的特性，例如：(a)亮度与电压的关系、(b)亮度与电流密度的关系、(c)功率效率 与电流密度的关系。作为参考，图中还包括了没经过等离子处理的OLED器件的特性。如图2 (a)所示,经过等离子体 He(10 slm)/O 2(3 slm)和He(10 slm)/SF 6(100 sccm)处理后的器件的开

10、启电压(定 义为发出1 cd/m2的亮度所需的电压)分别为 3.6V和3.2V,然而未经等离子体处理的器件的开启电压 为4.2V。因此，经过等离子体处理后开启电压减小了，而且经 He(10 slm)/O 2(3 slm)处理后的器件的 开启电压比经He(10 slm)/SF 6(100 sccm)处理后的电压低。此外，如图 2 (b)所示，在同一发光强度 的条件下，经 He(10 slm)/SF 6(100 sccm)处理的OLEDl!现出了最低的电流密度，而没经处理的 OLED 器件表现出了最高的电流密度。通过对电流密度的测量，得到了用三种方法He(10 slm)/SF 6(100 sccm

11、)、 He(10 slm)/O 2(3 slm)和未做处理的三个器件的最高功率效率分别为0.93 Lm/W、0.75 Lm/W 和0.58Lm/W)因此，经过 He(10 slm)/SF 6(100 sccm)处理的OLE湍件显示了最佳的电学性能。(UJFPU)Q>uuau5小二 Go-Hr>.xiaib-j oC g IC 1214Voltage (V)Kiftonr7000经过 He(10 slm)/SF 6(100 sccm)处理的 OLEDibV0 M 1D0150500550Current density (inA/cm1)-kWQ simj 匕6 口出嗣1翼融4：则 I

12、npul wMaye： 10 kV Processing lima： Jd器件的电特性的改善看上去与去除ITO表面的有机杂质和经处理的ITO工作性能的改变有关。表1显示了通过XPS测量的未经处理、He(10 slm)/O 乂3 slm)和He(10 slm)/SF 6(100 sccm)三种处理方法后 的ITO表面的组成。表中显示，经等离子处理后，ITO表面碳元素的含量显著的减少，而且，经He(10slm)/SF 6(100 sccm)处理后 的ITO表面碳含量最少，因 此，有机清洗后残留的有机 杂质被等离子体清除了很 多，有机杂质的去除被认为 改善了 OLED勺性能。f.4.2C.8.E.4

13、2.O IL 1 1 o OO.G 。(芝 E)Auuo石一toJoModnet&renoeInput voltage: lOkVProcessing time： 3Qsec05010015020C250Current density (mA/cmz)Fig. 2. Characteristics of the OLEDs fabricated on the ITO glass cleaned by the atmospheric pressure plmi udngsJm) andHeOsIml/SFti 1()0sccm) gas mixtures (a) Iujninescenc

14、c- voltape, <b) lumirx:sccncc-current dcnsitj and (c) power cffidcncy-currcnt density. .Xs a reference, the ckiracic ri sties of the OLED <lcice hbricaiccl 5 ithout plasma cleaning arc included.当比较用 He(10 slm)/O 2(3 slm)和 He(10 slm)/SF 6(100 sccm)处理的 ITO表面组成时发现，在用 He(10 slm)/SF 6(100 sccm) 清洁的

15、ITO表面的氧被12% 的氟代替，然而却没有发现 硫元素。ITO中氟的掺杂提 高了 ITO的电学特性，从而 推理出氧化锡中掺杂氟可以 提高空穴的注入效率。此外, X射线电子谱线数据显示， 即使在等离子处理后，锡锢 比值没有显著变化，而表面 Sn4+的含量却明显减少。 Sn3c5/2在峰值处可以分解成Sn2+和Sn4+的氧化物。图3显示了将Sn3cl5/2的峰值分解成Sn2+和Sr4+的XPS窄扫描数据。如图所示，经 过等离子体处理后的 Sn4+的最高值有所减小，在经 He(10 slm)/SF 6(100 sccm)处理后为最低的峰值。据报道，通过用In 3+代替Sn4+的位置来减少Sn4+的

16、含量，Sn4+的减少使n型的费米能级向中间能带改变， 从而提高了 ITO的工作性能。因此，经用 He(10 slm)/SF 6(100 sccm)处理的OLED器件的改善也与增 加氟元素和减少ITO表面Sn4+的含量来除去碳杂质以提高工作性能有关。I able I. Composition of the ITO surfaces not created (as is) and trcattxiwith He( 10siniJ/O?(3slm) and Hc 10slrn)/SFg(lOOsocm) measured by XPS.Atomic conccntratnsn (%) Ttcatme

17、ni method Cis I 口 3%2Sn3dM01s FIs Sn/lnAs isHc/Oi plasma(10slm/3 slin)He/SFb plasma(10 slm/1 (Mlseem)12.831.9G 7 Q7 7J 右J.8.6322A.450.9A0 1370.1301220,127结论，利用常压等离子体设备使He(10 slm)/O 2(3 slm)和He(10 slm)/SF 6(100 sccm)的混合气体来处理ITO玻璃的表面以及它对ITO表面特性和ITO经过处理的OLE湍件的特性的影响已经得到了研究。经过He (10 slm)/SF 6

18、(100 sccm)处理的OLE湍件拥有最好的电学特性，例如：最低的开启电压(在凫度均为 1cd/m2的前提下， He/SB处理后为3.2V, He/6处理后为3.6V,未处理的为4.2V)、最高的亮度(在相同的电流密度 下)和最高的功率效(=E- a=5uqc-率(He/SF6处理后为100000.93Lm/W( He/Q处理 后为0.75Lm/W(未处 理的为 0.58Lm/W)。He(10 slm)/SF 6(100 sccm)等离子体处理 的OLED器件性能的 改善与ITO表面有机 杂质的去除、Sn4+的30000non486A0&Binding energy (eV)4906

19、000050000Fig一 工 Nartxiw xcan XPS or (hr deconvidurul Sir4- tind Sni4+ pen心 from the SiiRds,： peak* of the F I O surfiivc Irciilcd with FIc(10,ilm)/ O二门3m) diuJ Tfc(10%1in)/SF6i lOOsccin). The XPS ddlH of the ITO in face nut IrcatcJ by ihc plaMiiH i al so iiK lixicd.ITO的影响含量的降低以及ITO表面氟元素的掺杂有关，而且表明了 I

20、TO性能的提高。因为常压等离子体不需要 真空室，所以能够很容易安装负载室并应用于尺寸大于 730mm*920mm基板，常压等离子体可以成功 的应用于商业制造OLE邛ITO的清洗环节。SF6低压等离子体处理和常压等离子体处理对文档来源为 :从网络收集整理.word 版本可编辑.欢迎下载支持正在进一步观察中。这个课题得到了商务部、 工业和能源部以及韩国科技部的国家研究实验室计划 (海军研究实验所)的支持。参考文献1) C. W. Tang and S. A. VanSlyke: Appl. Phys. Lett. 51 (1987) 913.2) F. Li, H. Tang, J. Andere

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25、1 (2004) 85.15) S. Kanazawa, M. Kogoma, T. Moriwaki and S. Okazaki: J. Phys. D 21(1988) 838.16) H. E. Wagner, R. Brandenburg, K. V . Kozlov, A. Sonnenfeld, P .Michel and J. F. Behnke: V acuum 71 (2003) 417.17) S. Wang, V. Schulz-von der Gathen and H. F. Dobele: Appl. Phys.Lett. 83 (2003) 3272.18) O.

26、 P. Agnihotri, A. K. Sharma, B. K. Gupta and R. Tangaraj: J. Phys.D. 11 (1978) 643.19) A. Andersson, N. Johansson, P. Broms, N. Yu, D. Lupo and R.Salaneck: Adv. Mater. 10 (1998) 859.Characteristics of Organic Light-Emitting Devices by the SurfaceTreatment of Indium Tin Oxide Surfaces Using Atmospher

27、ic PressurePlasmasChang Hyun JEONG, June Hee LEE, Yong Hyuk LEE, Nam Gil CHO, Jong Tae LIM,Cheol Hee MOON and Geun Young YOMEDepartment of Materials Science & Engineering, Sungkyunkwan University, Suwon, 440-746, KoreaPDP Division, Samsung SDI Co., Ltd., Cheonan, 330-300, Korea(Received October

28、4, 2004; accepted October 28, 2004; published December 10, 2004)5ABSTRACT ： This study examined the effects of a He/O 2 and He/SF6 atmospheric pressure plasma surface treatment of indium tin oxide(ITO) glass on the ITO surface and electrical characteristics of organic light emitting diodes (OLEDs).

29、The OLEDs composedof ITO glass/2-TNATA/NPD/Alq 3/LiF/Al showed better electrical characteristics, such as lower turn-on voltage, higher power efficiency, etc., after the He/O 2 or He/SF6 plasma treatment. The He/SF6 treatment resulted in superior electrical characteristics compared with the He/O2 tr

30、eatment. The electrical improvement as a result of the He/SF 6 and He/O2 plasma treatments is related to the decrease in the carbon and Sn4t concentration on the ITO surface and fluorine doping of the ITO possibly indicating a change in the work function as a result of the treatments. DOI: 10.1143/

31、KEYWORDS ： ITO, surface treatment, atmospheric pressure plasma, OLED, He/O2, He/SF6Organic light emitting diode (OLED) displays have been extensively studied due to their superior properties such as faster response time, lower operating voltage, higher quantum efficiency, etc. in addition to the sim

32、pler deposition processing and lower manufacturing cost compared with other flat panel displays such as liquid crystal displays and plasma display panels.1 为 Currently, these devices are manufactured in a high vacuum chamber for substrate areas smaller than 370mm 470mm using a multilayer evaporation

33、 technique for monomer organics, and deposition techniques for the large area substrates close to 920mm 730mm are currently under development. In addition, OLED displays utilizing polymer organics, which use inkjet printing instead of vacuum evaporation, are actively being studied4.,5)On OLED device

34、s, a transparent conductor is used for the higher optical transparency, and among the various transparent conductors, indium tin oxide (ITO) is the most widely used due to its high conductivity and transparency. In order to form OLED devices, the organic monomers are deposited on patterned ITO glass

35、 for the formation of a low resistive ohmic contact. The contact resistance between the ITO and organic materials of the OLED devices can be altered by the ITO surface preparation due to the organic materials on the ITO glass surface and the change in the ITO composition as a result of the ITO surfa

36、ce preparation method. ITO is a nonstoichiometric compound. Therefore, the chemical composition can be easily changed.6) Consequently, in order to improve the contact properties between the ITO and the organic material of the OLED, the surface treatment of the patterned ITO before depositing the org

37、anic materials is very important.6 13) As surface treatment methods, low pressure plasma techniques，0,12) UV/O 3 techniques”1) and wet treatments12,13) have been used to remove the organic materials and improve the ITO surface properties. However, these techniques are expensive and difficult to scal

38、e to large areas using low pressure plasma and UV/O3 techniques. In addition, there are environmental issues in the case of wet treatment.Atmospheric pressure plasma such as a corona discharge,14) dielectric barrier discharge (DBD), 15,16) atmospheric plasma jet,17) etc. for the treatment of various

39、 surfaces applied to electric materials, electronic materials, biomaterials, structural materials, etc. have been actively studied in order to replace low pressure plasma techniques, wet processing, etc. This study examined the potential of using atmospheric pressure plasma for the surface treatment

40、 and cleaning of ITO glass for OLED devices. As an atmospheric pressure plasma cleaning technique, a modified DBD, which can be scaled to large areas and show a higher plasma density than conventional DBD, was used. By varying the gas mixture in the modified DBD, the effects of the gas mixture on th

41、e characteristics of the ITO surface and on the electrical properties of the OLED devices formed on the cleaned ITO glass were investigated.Figure 1 shows a schematic diagram of the atmospheric pressure plasma equipment used in this study for 6文档来源为：从网络收集整理.word版本可编辑.欢迎下载支持the surface treatment of I

42、TO glass. As shown in the figure, the modified DBD used in this study was composed of a pyramid shaped multi-pin electrode as the power electrode instead of a plate electrode, a plate electrode as the ground electrode, and dielectric materials on both electrodes. Using the multi-pin electrode instea

43、d of a blank plate electrode, a higher plasma density and gas breakdown at a lower AC voltage could be obtained by forming a high electric field on the tip of the pins similar to the corona discharge with a higher stability and glow discharge shape instead of a filamentary discharge shape. The AC vo

44、ltage in the range from 3 to 15 kV with a frequency of 20 -30 kHz was connected to the multi-pin power electrode and the ground was connected to the plate ground electrode.Fig. 1. Schematic diagram of the atmospheric pressure plasma equipmentused for the surface treatment of ITO glass.He(10 slm)/O2(

45、3 slm) and He(10 slm)/SF6(100 sccm) were used as the ITO surface cleaning gas mixtures for the OLED devices. Before the plasma treatment, all the ITO glasses were cleaned with an organic solvent. These optimum gas compositions were selected after measuring the contact angle by a contact angle measur

46、ing tool and the carbon contents on the ITO surface by X-ray photoelectron spectroscopy (XPS, VG Microtech Inc., ESCA2000) after varying the O 2 flow rate from 0 to 3 slm and the SF6 flow rate from 0 to 500 sccm with a He flow rate of 10 slm. The AC voltage used was 10 kV at 25 kHz and the processin

47、g time was 30 seconds. The composition of the ITO surface after cleaning with the He/O2 and He/SF6 plasma was investigated by XPS using Al KX-ray source of 1486.6 eV.The OLED devices were fabricated on the cleaned ITO by the thermal evaporation of the OLED materials andelectrode materials sequential

48、ly without breaking the vacuum.The OLED structure used in this study was ITO glass/2-TNATA(60 nm)/NPD(20 nm)/Alq 3(40 nm)/LiF(1 nm)/Al(100 nm). The deposition rates of the organic materials, LiF, and Al were 0.3 -0.5? /s, 0.1 ? /s, and 0.5 -5 ? /s, respectively. The fabricated device active area was

49、 4mm2. The electrical characteristics of the fabricated OLED devices were measured using an electrometer (Keithley 2400) and the luminescence characteristics were determined by measuring the photocurrent induced by light emission from the OLEDs using a picoammeter (Keithley 485).Figure 2 shows the c

50、haracteristics of the OLEDs fabricated on the ITO glass cleaned by the atmospheric pressure plasma using the He(10 slm)/O2(3 slm) and He(10 slm)/SF6(100 sccm) gas mixtures such as (a) luminescencevoltage, (b) luminescence-current density, and (c) power efficiency-current density. As a reference, the

51、 characteristics of the OLED device fabricated without plasma cleaning were included. As shown in Fig. 2(a), the turn-on voltages of the devices (defined as the voltage required to deliver a luminescence of 1 cd/m2) after the He(10 slm)/O2(3 slm) and He(10 slm)/SF6(100 sccm) treatment were 3.6V(h)/O

52、OJHJOJLW.JQO3200JCurrent density (mA/cm )一rvgrvrig (10(lm/3-x- Hc/SR Him/100 jrecffi)hput vottage： 10 kVilm». 3 口 tKand 3.2 V, respectively, while the turn-on voltage of the device without the plasma treatment was 4.2 V. Therefore, after the plasma treatment, the turn-on voltage was decreased a

53、nd the He(10 slm)/O2(3 slm) treatment showed a lower turn-on voltage than the He(10 slm)/SF6(100 sccm) treatment. In addition, as shown in Fig. 2(b), the OLED treated by He(10 slm)/SF6(100 sccm) showed the lowest current density at the same emission intensity while the81003文档来源为 :从网络收集整理.word 版本可编辑.

54、欢迎下载支持OLED fabricated without the plasma treatment showed the highest current density. When the power efficiency was measured as a function of the current density, the highest power efficiencies were 0.93 Lm/W, 0.75 Lm/W, and 0.58 Lm/W for the He(10 slm)/SF6(100 sccm) treated sample, He(10 slm)/O2(3

55、 slm) treated sample, and the non-treated sample, respectively. Therefore, after the He(10 slm)/SF6-(100 sccm) treatment, the device showed the best electricalperformance.Fig. 2. Characteristics of the OLEDs fabricated on the ITO glass cleaned by the atmospheric pressure plasma using He(10 slm)/O2(3

56、 slm) and He(10 slm)/SF6(100 sccm) gas mixtures. (a) luminescence-voltage, (b)luminescence-current density, and (c) power efficiency-current density.As a reference, the characteristics of the OLED device fabricated withoutplasma cleaning are included.The improved electrical characteristics shown for

57、 the OLED after the He(10 slm)/SF6(100 sccm) treatment appeared to be related to the removal of the remaining contaminants on the ITO surface and the change in the work function of the ITO as a result of the plasma treatment. Table I shows the composition of the non-treated (as is) and He(10 slm)/O2

58、(3 slm) and He(10 slm)/SF6(100 sccm) treated ITO surface measured by XPS. As shown in the table, carbon contamination on the surface decreased significantly as a result of the plasma treatment and the ITO surface after the He(10 slm)/SF6(100 sccm) treatment showed the lowest carbon content on the surface. Therefore, the organic contaminants remaining after organic cleaning were removed further after the plasma cleaning, and the removal of the organic contaminants is believed to be partially responsi