The Improvement In Structure And Performance Of Two-band White Organic Light-emitting Diodes

Organic light emitting diodes are currently considered as next generation displays and lighting sources technology for its energy saving, large visual angle, high luminous efficiency, fast response, no glare and flexible etc. OLED has more than20years of development history, there are still some issues to be improved, such as high cost, rambunctious color stability and further efficiency, so that OLED has not been popular in our life. According to the above questions, this paper starts from the luminous principle of OLED, optimizing the structure of the device and other methods are used to improve the performance of the two-band white organic light emitting devices.The main research content of this paper is as follows:Firstly, Aiming at the high voltage of white fluorescent OLED, the red fluorescent material DCJTB and blue fluorescent material OXD-7compose of two-band white OLEDs have been designed, by matching energy level difference and improving the transport of carrier to reduce the turn-on voltage of the device.By adding suitable materials as buffer layer, to reduce the energy level difference between hole transport layer and the light emitting layer; Doping CBP to the blue fluorescent material OXD-7, not only regulate the energy level difference, also makes the transfer of carrier in the device smoothly.Secondly, For roll-off phenomenon in phosphorescent OLEDs and color stability problem at high luminance, the mCP doped Firpic as blue light-emitting layer and the CBP doped Ir (MDQ)2acac as red light-emitting layer two-band white OLEDs have been designed. By means of increasing the mCP to study the compound area of electrons and holes in blue phosphorescent devices based on Firpic. And use this way to improve the efficiency and color stability of white phosphorescent devices. Adding monolayer mCP effectively adjusts the energy distribution of the light emitting layer, it makes the maximum current efficiency of the device improve. Adding a monolayer mCP also can enhance the stability of color coordinate.Thirdly, For Hybrid OLEDs, a large number of triplet excitons in phosphorescent layer back to the fluorescent layer causes many triplet excitons to emit no light, the Firpic as the blue phosphorescent material and DCJTB as red fluorescent material compose of two-band white OLEDs have been designed. Adding intermediate blocking layer TCTA and improving energy level difference to adjust energy transfer of the triplet exciton, which leads to improving the light color and brightness of the device. The ntermediate blocking layer improved the intensity blue light so that it makes the lignt olor into the white area.