Preparation And Research On Organic Light-emitting Diodes Based On Perylene

Organic light-emitting diode(O LED),due to its self-luminescence,low consumption and high color saturation characteristics,has become the most promising display and lighting technology.Especially,a white organic light-emitting diode has always been a hot spot in research,and its high-performance have been continuously achieved.In this thesis,a traditional blue fluorescent material perylene was used as a blue emitter,high-efficiency and stable non-doped blue and white devices were fabricated and studied based on thin layer structure.In the research of blue OLED,firstly,two kinds of blue OLEDs with different light-emitting layers based on perylene were prepared.The light-emitting layers were0.3-nm-thick perylene ultra-thin layers placed on both sides of a co mmon ambipolar host material C BP(4,4'-n,n'-dicarbazole-biphyenyl),and perylene doped in CBP to form a doping system(C BP:1.0 wt%perylene),respectively.The results show that the ultra-thin insertion method not only simplify the fabrication process,but also improve the performance of the device.Then,the thicknesses of perylene in the non-doped devices were further optimized to be 2 nm.The maximum brightness and external quantum efficiency were 16200 cd/m~2 and 3.0%(3.72 cd/A),respectively,corresponding to CIE(Commission Internationale de l'Eclairage)color coordinates of about(0.14,0.15).At last,combined with the prepared single carrier devices,the performance and electroluminescence mechanism of the devices were analyzed.It was proved that although the F?rster energy transfer from CBP to perylene may exist,carrier confining induced exciton direct formation mechanism is considered to dominate in the process of electroluminescence.Based on the above research results,non-doped white OLEDs were fabricated by inserting an ultra-thin layer of 0.2 nm-thick orange fluorescent material rubrene in CBP of the blue OLED.In the experiment,when rubrene layer was located in the middle of C BP or 10nm away from perylene in the cathode side,the white device exhibits the highest efficiency of6.6 cd/A(external quantum efficiency of 2.6%)and the highest brightness of 18480 cd/m~2.In this configuration of positions of perylene and rubrene,the ratio of the blue from perylene and the orange from rubrene reaches optimum.And in the research process,it is found that the CIE color coordinates of o ne of the devices reach the ideal white light equilibrium point(0.33,0.33)at a current density of 200 m A/cm~2.The behavior of chromaticity of this device changes with increasing voltage may be due to the field-induced quenching effect of rubrene exciton.