利用p型掺杂技术制备的高效有机电致发光器件  

Highly Efficient Organic Light-emitting Devices Achieved by p-type Doped Hole Injection Layer

作　　者：陈宇[1,2] 王鹏[1,2] 郭闰达[1,2] 岳守振[1,2] 赵毅[1,2] 刘式墉[1,2] 

机构地区：[1]集成光电子学国家重点联合实验室吉林大学实验区 [2]吉林大学电子科学与工程学院,长春130012

出　　处：《光子学报》2013年第2期139-143,共5页Acta Photonica Sinica

基　　金：国家重点基础研究发展计划(No.2010CB327701);国家自然科学基金(No.60977024)资助

摘　　要：利用氧化钼(MoOx)作为p型掺杂剂,以掺杂层4,4′-bis(carbazol-9-yl)biphenyl(CBP):MoOx作为空穴注入层,制备了一种结构为ITO/MoOx/CBP∶MoOx/CBP/CBP:tris(2-phenylpyridine)iridium(III)(Ir(ppy)3)/4,7-diphenyl-1,10-phenanthroline(Bphen)/LiF/Al的有机电致发光器件.器件中CBP同时作为空穴注入层、空穴传输层以及发光层母体材料,这种结构具有结构简单同时能有效降低空穴注入势垒等优点.研究发现,随着空穴注入层厚度的增加,器件的电流密度增加,表明p型掺杂层的引入能够有效增强空穴的注入;通过优化器件空穴注入层与空穴传输层厚度,器件性能有所提高,最大电流效率为29.8cd/A,可以认为合理的优化空穴注入层和空穴传输层的厚度,使载流子在发光层中的分布更加平衡是提高器件发光效率的主要原因.值得指出的是,从电流效率最大值到亮度为20 000cd/m2时,优化后器件的效率衰减仅为17.7%,而常规器件的效率衰减则为62.1%,优化后器件效率衰减现象得到了明显的改善.分析认为优化后的器件中未掺杂的CBP有助于展宽激子形成区宽度,进而减弱了三线态-三线态湮灭、三线态-极化子淬灭现象,激子形成区的展宽是改善效率衰减的主要原因.Organic light-emitting devices based on molybdenum oxide（MoOx） doped 4,4’-bis（carbazol-9-yl）biphenyl（CBP） as a p-type doping hole injection layer was demonstrated.The devices comprise the following structure： ITO/MoOx/CBP∶MoOx/CBP/CBP：tris（2-phenylpyridine）iridium（III）（Ir（ppy）3）/4,7-diphenyl-1,10-phenanthroline（Bphen）/LiF/Al,where CBP acts as hole injection layer（HIL） and hole transport layer（HTL） as well as the host metarial of emitting layer（EML）.The simple structure also has the the benefit of lowing the injection and transpotring barrier of holes.With the thickness of HIL increasing,the current density of device increases,indicating the p-type doping layer has a good performance of enhancing the holes injection.The performance of the device can be improved through optimizing the thickness of HIL and HTL.The maximum current efficiency of optimized device is 29.8 cd/A,which can be attributed to the more balanced distribution of carrier in EML.It is noteworthy that the efficiency roll-off of optimized device is only 17.7% between maximum and 20 000 cd/m2,comparing to that of conventional device（62.1%）.The undoping CBP layer in optimized device can help to extend the distribution zone of excitons,reducing the possibility of triplet-triplet annihilation and triplet-polaron annihilation,this can be accounted for the improved efficiencies and reduced efficiency roll-off.

关 键 词：有机电致发光器件 P型掺杂 效率衰减 

分 类 号：TN383.1[电子电信—物理电子学]