【作者】 娄双玲；

【导师】 于军胜；

【作者基本信息】 电子科技大学 ， 光学工程， 2009， 博士

【摘要】 有机电致发光器件（Organic light-emitting diodes，OLEDs），具有自发光、响应快、全固态、制备工艺简单、高效率、宽视角、超薄、耐高低温、柔性等优点，被誉为最理想和最有潜力的下一代显示技术。从目前有机材料的性能上看，高发光效率和稳定化学性能的材料还比较少。在不同发光颜色的材料中，绿色材料性能最为优异，红色材料次之，而蓝色材料效果相对最差，因此阻碍了全彩色器件和白光器件的产业化步伐。针对上述问题，本论文对几种空穴传输材料、空穴阻挡材料的性能进行研究，重点是对几种新型芴类小分子蓝光材料及器件性能方面进行系统的研究，具体包括：1．对常规的双层结构（即空穴传输层（Hole transporting layer，HTL）／发光层（Emitting layer，EML））进行发光层厚度优化研究工作，并且采用常规材料和器件结构作参考，考察几种新型的空穴传输材料和硼类空穴阻挡材料的性能。结果发现，含有芴基团的TPD衍生物的玻璃化温度（Glass-transition temperature，Tg）比TPD材料高出近20℃，但空穴传输能力不如TPD材料；通过设计双HTLs结构（即TPF-OMe／TPD），得到了高性能器件，在4．5 V电压下器件的最大流明效率达到1．06lm／W。另外，双键结构的DMBSB硼类材料具有优良的阻挡空穴能力，而三键结构的DMBPA材料的空穴阻挡能力较弱。2．利用星形结构的芴类小分子HKEthFLYPh材料与NPB、Alq₃和Rubrene之间的F（?）rster能量转移现象，制备了非掺杂结构的白光OLEDs（White OLEDs，WOLEDs）。其中，NPB／HKEthFLYPh／Alq₃结构的WOLED在15 V电压下，亮度达到8800 cd／m²，在5．5 V电压下，具有最大流明效率1．0 lm／W和最大电流效率1．8 cd／A。引入Rubrene黄光染料，并通过调整器件结构，得到了色坐标位于（0．34，0．33）的白光器件。3．针对当前芴类蓝光材料的发光不稳定性问题，即长波长发射现象，以共轭结构的芴类小分子BFLBBFLYQ材料为探针，从有机薄膜的旋涂和真空蒸镀两种不同处理工艺上，利用紫外可见吸收光谱、荧光光谱（Photoluminescence，PL）、电致发光光谱（Electroluminescence，EL）和傅里叶红外光谱（Fourier-transform infrared，FTIR）对材料及器件性能进行了系统性的考察。研究结果排除了激基缔合物／聚集体是产生长波长发射的原因，肯定了芴酮缺失是导致材料发光不稳定的主要因素。另外，观察到了BFLBBFLYQ：TPD在氯仿溶液中的显色现象，并且讨论了BFLBBFLYQ：TPD混合薄膜的激基复合物（Exciplex）发光现象。4．研究了几种含有氟（Fluorine，F）吸电子基团的芴类小分子材料的发光性能，结果发现随着材料中F取代基的引入和增多，材料的吸收光谱、PL光谱、EL光谱都发生红移；器件的启亮电压降低；电流密度增大；发光亮度和效率得到提高。但材料与NPB之间形成了激基复合物发光，通过在有机层界面处引入CBP材料，得到了来自芴类材料的蓝光发射，且具有很高的发光稳定性。另外，基于激基复合物发光现象，制备了几种发光颜色可调的器件以及色坐标位于白光中心（0．33，0．33）附近的WOLEDs器件。综上所述，本工作解析了导致芴类小分子材料发光不稳定的主要原因和机理，并且发现通过在分子结构中引入吸电子基团可以增加芴类小分子材料发光的稳定性，这些工作为下一步开发新型芴类发光材料及其高稳定性、高效率的OLED提供了借鉴。同时，双层HTLs的设计，三层非掺杂结构的白光器件的制各，以及利用CBP材料抑制激基复合物发光的方法，为OLED领域里器件机理的研究和高性能器件的制备提供了有力的依据和参考。更多还原

【Abstract】 Organic light-emitting diodes（OLEDs）,which have high potential as the mostideal and potential display technology in the 21^st century,possess many advantages,e.g.,self-emission,fast response,full solid device,easy fabrication,high efficiency,wideview-angle,ultrathin thickness.However,organic materials with high light-emittingefficiency and stability hinder OLEDs from large scale production.The performance ofgreen emitting materials is the highest in primary colors,and that of blue emittingmaterials is the lowest.Aiming at those problems,some hole transporting materials andhole blocking materials have been characterized,and some novel blue emitting fluorenesmall molecule materials and devices have been systematically investigated in thiswork.1.The thickness effects of emitting layer（EML） on the performances of holetransporting layer（HTL）/EML double-layer devices were investigated.Then severalnovel hole transporting materials and boron hole blocking complexes were comparedwith normal assistant materials.The results showed that the four derivatives of TPDcontaining fluorene framework had nothing on TPD except their glass-transitiontemperature（Tg） were almost 20℃higher than TPD.Whereas high performancesdevice with double HTLs（TPF-OMe/TPD） was obtained,that had the maximumefficiency of 1.06 lm/W at 4.5 V.In addition,DMBSB material with double bond hadexcellent hole blocking capability just like BCP,and DMBPA material with triple bondhad inferior hole blocking capability.2.White OLEDs（WOLEDs） were fabricated with non-doped structure based onthe F（o|¨）rster energy transfer from the starburst configuration HKEthFLYPh material toNPB,Alq₃ or Rubrene.The WOLED with structure of NPB/HKEthFLYPh/Alq₃ wasobtained with the highest luminance of 8800 cd/m² at 15 V,the maximum luminanceefficiency of 1.0 lm/W at 5.5 V and the maximum current efficiency of 1.8 cd/A at 5.5 V,and which showed a stable current efficiency.Furthermore,pure WOLED withCommission Internationale de L’Eclairage chromaticity（CIE） coordinates of（0.34,0.33）were obtained by introducing Rubrene yellow dye and optimizing device structure. 3.Aiming at the emission instability of fluorene blue emitting materials viz.lowenergy emission,using the conjugated configuration BFLBBFLYQ material as a probe,the performances of materials and devices based on films by spin-coating method andvacuum evaporated deposition were studied via UV-Vis absorption,photoluminescence（PL）,electroluminescence（EL） and Fourier-transform infrared（FTIR） spectra.Theresults showed that fluorenone defects were the origin of low energy emission and theformations of aggregate and excimer were excluded.Moreover the chromism ofBFLBBFLYQ:TPD blend in chloroform polar solvent upon UV irradiation and exciplexemission in BFLBBFLYQ:TPD film were observed and discussed.4.The emission properties of fluorene small molecules with Fluorine（F）auxochrome were investigated.The absorption,PL and EL spectra of materials had ared-shift phenomenon by increasing the number of F substituents,and the turn-onvoltage of device decreased,current density increased,luminance and luminousefficiency were improved.The exciplex emissions were formed between the fluorenemolecule and NPB.Pure and stable blue light of fluorene materials were obtained byinserting CBP layer at the organic interface.Otherwise,the color-tunable OLEDs andWOLEDs were fabricated based on exciplex emissions.In summary,this work paves the way for novel fluorene materials design and highstability and efficiency OLEDs fabrication based on the research focusing on theinstability of light-emitting properties of fluorene small molecules.And this workprovides some powerful evidences and references for further study on devicemechanism and high performance OLEDs via the design of double HTLs,thefabrication of non-doped triple-layer WOLEDs,and the method of eliminating theexciplex emission using CBP material.更多还原