The Properties Of The Complex Of Inorganic And Organic Light Emitting Diodes Modified On NaCl

The organic light emitting diodes is considered to be the revolution of display technology in the 21 st century. The reason is that OLED have the character of high contrast, seismic, wide color gamut, thin, large view angle, flexible in flat-panel displays. However, some problems, such as low luminance efficiency, low of the yield,the short of lifetime, have not to be resolved in the way of commercial application. The reason is that the mobility of the electron is slower than the hole in lots of organic materials like NPB and Alq3. For example, the mobility of the electron in Alq3 is10-5cm2/V·s which is slower than the hole that is 10-3cm2/V·s. The different mobility of the two carriers leads to the difference number of them which effect the luminance efficiency and the luminance of the OLEDs. Besides, the process of surplus cavity quenching with exciton generates lots of quantity of heat which is bad for the lifetime of the OLEDs. Therefore, we should keep the balance of the two carriers in the light emitting layer. Adding the electron injection layer and doping the electron translate layer are two methods. The carrier equilibrium constant k is proposed which is the ratio of the number of holes and electrons in the light emitting layer. This is conducive to research the problems in the field of OLEDs. The experiment compared the three methods of(1) the diodes having the electron injection layer only(2) the electron translate layer having been doped only(3) the diodes having the electron injection layer and the electron translate layer been doped together. The result is that the second way is the best. The structure of the B device: ITO/NPB(50 nm)/Alq3(35nm)/Alq3:NaCl(25 nm, 5.0 % wt)/Al(100 nm). A hole block layer of NaCl is added between ITO and the HTL which is in order to make the k closing to 1. The performance of the devices is best when the thickness of the NaCl is 1.0nm. The structure of the device: ITO/ NaCl(1.0 nm)/NPB(50 nm)/Alq3(35 nm)/Alq3:NaCl(25nm, 5.0 % wt)/Al(100 nm). The maximum brightness of the device is 17120 cd/m2 which is 1.52 times of B and 5.60 times of the normal device. The maximum luminance efficiency of the device is 3.92 cd/A which is 2.47 times of the normal device.