MoO3为缓冲层的高效非掺杂蓝色有机发光二极管

Highly Efficient Nondoped Blue Organic Light-emitting Diode Using MoO_3 as Anode Buffer Layer

以典型蓝色发光材料-联苯乙烯衍生物(4,4'-bis(2,2'-diphenylvinyl)-1,1'-biphenyl,DPVBi)为发光层,采用MoO3为阳极缓冲层制备了结构简单的非掺杂型蓝色有机电致发光器件。在电流密度为20 mA/cm2、MoO3缓冲层厚度为0.5 nm对器件效率约为无缓冲层器件效率的18倍,为通常酞菁铜(Copper phthalocya-nine,CuPc)缓冲层器件效率的1.2倍。器件启亮电压为3.3 V,最高外量子效率为3.1%,最高亮度达到16 000 cd/m2,器件CIE色坐标(Commission Internationale de l'Eclairage co-ordinates)为(0.15,0.15)。器件性能的提升归因于MoO3缓冲层的插入在阳极/有机层间形成了良好的欧姆接触。

Contact properties between electrodes and organic layers play a key role for the performance of an organic device.Ohmic contacts at electrode/organic interfaces are required for an ideal device.In order to improve performance of 4,4′-bis（2,2′-diphenylvinyl）-1,1′-biphenyl（DPVBi,a typical blue organic luminescent material） based organic light-emitting diode,MoO3 was introduced at anode interface as a buffer layer and a highly efficient bright nondoped blue electroluminescent device with low driving voltage was fabricated.Luminescent efficiency of the device with a 0.5-nm-thick MoO3 buffer layer is 18 times higher than that of the device without buffer layer,and 1.2 times higher than that of the device with a conventional copper phthalocyanine（CuPc） buffer layer at a current density of 20 mA/cm2.Turn-on voltage,maximum external quantum efficiency and luminance of the device are 3.3 V,3.1% and 16 000 cd/m2,respectively.Commission Internationale de l＇Eclairage（CIE） co-ordinates are（0.15,0.15）.Realization of excellent device performance is attributed to formation of ohmic contact between anode and organics by insertion of MoO3.