利用C_(60)和CuPc形成的有机半导体异质结作为阳极修饰层实现高效的磷光有机发光二极管

利用C_(60)和Cu Pc形成有机半导体异质结作为阳极ITO修饰层,制备了高效绿色磷光有机发光二极管(OLEDs)。与常规MoO_3阳极修饰层相比,C_(60)(5 nm)/Cu Pc(25 nm)面异质结修饰器件的最大电流效率和外量子效率(EQE)提高了12%和11%,分别为60 cd/A和16.8%;而Cu Pc∶C_(60)(30 nm,50%)体异质结修饰器件则提高了26%和27%,分别为67 cd/A和19.3%。高的器件效率一方面归因于C_(60)与Cu Pc异质结界面处积累的电荷会在电压的作用下形成高效的电荷分离和空穴注入,另一方面归因于异质结具有吸收绿光光子形成光生载流子的光伏效应。利用Cu Pc∶C_(60)体异质结修饰阳极的器件由于具有更高效的电荷积累、更合适的空穴传输性、更平衡的载流子复合和更好的光伏特性,器件效率要比C_(60)/Cu Pc更优。研究表明,这种基于C_(60)与Cu Pc的有机半导体异质结可作为优越的ITO阳极修饰层。

High Efficient Phosphorescent Organic Light-emitting Diodes Based on Organic Semiconductor Heterojunctions of C60 and CuPc as Anode Modified Layer

High efficient green phosphorescent organic light-emitting diodes ( OLEDs) were fabrica-ted based on semiconductor heterojunctions of C60 and CuPc as the anode modified layer. Compared with the reference device based on MoO3 as the anode modified layer, the maximum current efficien-cy and EQE for C60(5 nm)/CuPc(25 nm) planar heterojunction modified device are improved by 12% and 11%, reaching up to 60 cd/A and 16. 8%, respectively; and the values for CuPc:C60 (50%, 30 nm) bulk heterojunction based device are increased by 26% and 27%, arriving at 67 cd/A and 19. 3%, respectively. On one hand, the superior device efficiency based on heterojunc-tion modified layer can be attributed to efficient dissociation and hole injection of accumulated char-ges generated in the heterojunction interfaces driven by the external electrical field. On the other hand , the higher efficiency is also attributed to the photovoltaic effect of heterojunction which can u-tilize the green photon to produce photon-generated carriers. Due to the more efficient charge accu-mulation and more proper carrier transport property, more balanced recombination of carriers and better photovoltaic effect, the bulk heterojunction modified device owns the higher efficiency compa-ring with the planar heterojunction modified device. The study demonstrates that the organic semi-conductor heterojunction can become a kind of superior anode modified layer.