The Research Of Organic/Inorganic Hybrid Electroluminescent Devices

In recent years, organic electroluminescent devices has become a hot area because of its many advantages such as high brightness, high contrast, low driving voltage, high response speed and light quality, membrane thickness, preparation, low cost, and can make the flexible device and so on. These advantages will make it become a promising technology in the future. However, the instability and the low mobility of organic material are two main reason for its low luminous efficiency and low yield. Compared with organic electroluminescent devices, the light-emitting diodes (LEDs) have a long development history and its technology is relatively mature. So it has a widely use in photoelectric display field. Inorganic semiconductor material has high carrier transmission efficiency. The device based on it has stable performance and good efficiency. But device preparation process complicated and costly, these are the bottleneck of restricting its further development.Due to organic and inorganic optoelectronic devices both have advantages and disadvantages, so in order to get better performance of electroluminescent devices, researchers combine these two kinds of material to give full play to their advantages and finally they get a compound electroluminescent device. This paper mainly studied the following two contents:The first part we studied the effect of inorganic materials PbI2 that between the ITO anode and hole transport layer. The ITO was modified by PbI2 with different thickness and these treated ITO was used to make OLED. It was found that the performance of device is best when the thickness of PbI2 is 2nm. At the same time, we prepared the same two structures based on oxygen plasma treated ITO and did not make any processing of ITO respectively. The experimental results showed that these two devices based on PbI2-ITO and oxygen plasma treated ITO have similar performance. When the device under the optimal thickness of Pbh, the maximum brightness is 40000cd/m2, the maximum current efficiency is 43cd/A. the threshold voltage is 4V. Compared with the device based on cleaned ITO, the current efficiency of the device used PbI2-ITO improved by 53%, the brightness increased by 5 times, the threshold voltage decreased significantly and the life time improved significantly.The second part we studied the effect of doping inorganic material and organic material for the performance of the device. We fabricated hole-transporting layer that doped inorganic material(Se) with hole-transporting material(NPB). It was found that the performance of device was best when doping concentrations of NPB and Se was 3:2.Compared with the device that without doping the device after doping has bigger current under the same voltage. By fitting calculation we obtained that before and after doping the device carrier mobility increased from 2.03×10-7 cm2/V·s to 8.31 ×10-6 cm2/V·s, expanded by 40 times, indicating that doping with inorganic materials did help to improve device carrier mobility. However, the device after doping has a lower brightness and lower current efficiency. This is due to the deep color of Se absorbed the photons from the emission layer, which caused the loss of light.