【作者】 蒋泉；

【导师】 成建波；

【作者基本信息】 电子科技大学 ， 光学工程， 2008， 博士

【摘要】 有机发光二极管（organic light-emitting diode，OLED）或称有机电致发光器件，由于具有自发光、响应快、全固态、宽视角、超薄、耐高低温等优点，在平板显示技术领域是目前国内外研究的热点之一。本论文在透明OLED器件的制备、无源矩阵OLEDs（Passive matrix OLEDs，PMOLEDs）屏和全彩高分辨率PMOLEDs显示系统的研究、掺杂型绿色器件的结构优化和工艺方面进行了一系列的探索性和创新性的工作，具体包括：1．使用低功函数和高稳定性的六硼化镧（LaB₆）材料作为透明阴极，制作了LaB₆／Alq₃／NPD／Au和ITO／TPD／Alq₃／LaB₆两种OLED器件。LaB₆薄膜是使用电子束蒸镀工艺来制备的，当LaB₆薄膜厚度1800（?）时，薄膜透过率约为70％，方阻约为35Ω／□。LaB₆／Alq₃／NPD／Au器件发光面为LaB₆阴极，开启电压大约为2．4V，器件的最大电流效率为2．46cd／A，此时对应的驱动电压为2．6V。在驱动电压15V时，电致发光光谱峰值波长为534nm，色度坐标为（0．287，0．652）。ITO／TPD／Alq₃／LaB₆为透明OLED器件，器件的开启电压大约为2．8V，17V时器件亮度可达5650cd／m²。电压5．0V时得到最大电流效率4．36cd／A。LaB₆阴极一侧的发光光谱与ITO阳极一侧相比，峰值波长红移了约8nm，部分原因可能是微腔效应。2．采用矩阵网络分析方法，建立了PMOLEDs屏的简化和准确等效电路，可系统、简化地分析PMOL正Ds屏的交叉串扰现象，如OLEDs具有良好的整流特性，采用逐行寻址驱动技术时，交叉串扰影响较小。仿真计算了OLEDs行、列电极的电压降，因为OLEDs是电流型器件，必须采用恒流源驱动，如用恒压源驱动，在行、列电极上产生的电压降将会严重影响图象亮度的均匀性。建立了计算PMOLEDs功耗的数学模型，模型表明采用双屏驱动的OLEDs与单屏相比，随着屏的尺寸的增加，器件的功耗可得到显著的降低。制作了两个绿色小分子无源矩阵OLEDs，器件的尺寸为2．5″，分辨率为128×64。测试结果验证了功耗模型，当二者工作亮度均为100cd／m²时，采用双屏驱动的OLEDs的功耗比单屏的降低了25％。3．利用AutoCAD软件包设计了128×160高分辨率全彩OLEDs屏的基板、以及与基板配套的4张光掩模、2张机械掩模图案以及FPC和COF。4、利用分立元件设计了全彩PMOLEDs屏的驱动电路，驱动电路采用了预充电技术，首先用一电压源对OLED的寄生电容充电将其电压充到启亮电压附近，再用一程控电流源驱动OLED使之发光，R、G、B三色OLED像素的预充电电压分别被设定为3．0V、2．0V和2．9V；设计了全彩PMOLEDs屏的显示系统，显示系统使用DVI接口将显示数据从微机传输到FPGA进行数据处理，FPGA将1 8位的显示数据和时钟信号传输给驱动电路。OLEDs屏能实现262144种颜色。当屏平均工作亮度为40cd／m²时，寿命预计超过5000小时，功耗约为300mW。5．研究了两种不同空穴材料（2-TNATA和CuPc）对掺杂型OLED器件性能的影响。器件的电流-电压-亮度关系的测试结果，两种器件在低电压情况下（＜5．7V），电极和有机层为欧姆接触；而在较大的电压情况下，满足陷阱电荷限制传导机制。测试结果表明作为空穴注入材料，2-TNATA的性能优于CuPc。以2-TNATA为空穴注入层，研究了其厚度对器件光电性能的影响。结果表明，当2-TNATA厚度为35nm时，器件的性能最优。当驱动电压分别为13V时，器件的亮度和电流效率分别为3280cd／m²、1．377cd／A。在有机发光器件中的微腔效应并没有对器件的发光光谱带来很大的影响，因此基本可以忽略。6．研究了绿色荧光染料C-545T掺杂在Alq₃发光层对OLED器件性能的影响，并优化了掺杂浓度。当C-545T掺杂浓度为1．5 wt％时，器件的效率最高；当掺杂浓度大于1．5 wt％时，有较明显的浓度猝灭现象。外加电压19．5V时，器件的亮度达到了10650cd／m²，最大电流效率为6．16cd／A。C-545T掺杂对器件的发光光谱影响较大，掺杂1．0 wt％和2．5 wt％的峰值波长差为26nm，有明显的红移现象。更多还原

【Abstract】 Organic light-emitting diode （OLED） is also named as organic electroluminescencedevice.The OLED technology develops very quickly because of its advantages,suchas self-emission,fast response,full solid device,large viewing angle,ultra-thinstructure,and wide-temperature operating range.1.Two kinds of OLED with Lanthanum hexaborides （LaB₆） as transparent cathodewere fabricated.The structures of two kinds of OLED are LaB₆/Alq₃/NPD/Au andITO/TPD/Alq₃/LaB₆,respectively.LaB₆ film,with transparency of～70% and sheetresistance of 35Ω/□when the thickness of film is about 1800（?）,was prepared by theelectrons-beam evaporation.Turn-on voltage of LaB₆/Alq₃/NPD/Au is 2.4V,andmaximum current efficiency is 2.46cd/A at 2.6V.Peak wavelength of EL spectrum is534nm at 15V,and chromaticity coordinates is （0.287,0.652）.The device with thestructure of ITO/TPD/Alq₃/LaB₆ is a transparent OLED,whose turn-on voltage is 2.8V,maximum current efficiency is 4.36cd/A at 5.0V and luminance reach 5650cd/m² at 17V.Compared to the peak wavelength of spectra emitted from anode,the peak of spectraemitted from LaB₆ transparent cathode shifts～8nm to longer wavelength,due in part tomicrocave effect.2.A systematic and numerical analysis of the simple equivalent and exact equivalentcircuit of PMOLEDS was presented,and the crosstalk of PMOLEDS was analyzed.IfOLEDs have a good rectification,the crosstalk will have a very minor impact on theimage non-uniformity of PMOLEDs.Voltage drop on the electrode was quantitativelyanalyzed.Because the current dependence of voltage of OLED must meet the powerrelation,the minor voltage applied to each pixel will enable relative difference ofcurrent.So current-source is usually used to drive PMOLEDs.A mathematical model tocalculate the power consumption of PMOLEDs was presented.The models demonstratethat the power of dual-panel PMOLEDs can be significantly reduced compared withthat of single-panel PMOLEDs.Two 2.5-in.128×64-pixel green small moleculePMOLEDs was fabricated.One is single-panel,and the other is dual-panel.Comparedthe power consumption of single-panel with that of dual-panel PMOLEDs,the latter device show a reduction of 25% when both are operated at the average luminance of100cd/m².3.The pattern of substrate of full-color PMOLEDs （128×160）,four kinds of photomask and two kinds of shadow mask,FPC and COF was designed.4.Driving circuits using pre-charge technology of full-color PMOLEDs wasdesigned.By applying pre-charge,the pixel voltage reaches the target level quickly,andthe diode current flow at the corresponding desired level.The charged level of red,green and blue OLED was set to 3.0V,2.0V and 2.9V,respectively.The displayfeatures that control circuit can transform 18 bits gray-scale data from a PC to theOLED panel via a DVI channel.The lifetime of panel was estimated over 5000hbecause of the use of dual-scan driving technology,and the power consumption of thedisplay was about 300mw at the average luminance of 40cd/m².5.Green doped OLED with two different HIL,2-TNATA and CuPc were studied.Measurement of I-V-L curves two kinds of OLED show a ohmic contact betweenorganic layer and the electrode interface under low forward bias voltage （＜5.7V）,andI-V in agreement with trap-charge limited conduction under high forward bias （＞5.7V）.The efficiency of OLED using 2-TNATA as HIL is better than that of CuPc.Moreover,device with the different thickness of 2-TNATA was studied.The performance ofdevice with the 35nm thickness of 2-TNATA is the best.The luminance and currentefficiency is 3280cd/m² and 1.377cd/A at 13V.The thicknesses of HIL have a minorimpact on EL spectrum of device.6.Influences of different doping concentration of C-545T on OLED were studied.The device with 1.5 wt% doping concentration shows a maximum power efficiency of6.16cd/A,and a luminance of 10650cd/m² at 19.5V.Doping concentration of C-545Thas a great impact on EL spectrum,and there is a～26nm red-shift of the spectral peak.更多还原