Research On Photoelectric Properties Of Blue Phosphorescence Device Based On FIrpic Doping

In recent years, organic light-emitting devices have made great breakthrough in the emitting theory, functional materials and performance, but there are still problems faced with low efficiency, process complexity and high cost, especially in blue phosphorescent devices. Therefore, firstly we made a series of research on blue phosphorescent devices around the carrier injection balance and the internal quantum efficiency. Then from the external structure of OLED device, we manufactured and research on the micro lens array to improve the external quantum efficiency. Specific work is as follows:First of all, we researched on the emitting layer SimCP:FIrpic of blue phosphorescent devices from solvents, doping ratio and annealing temperature. The results show that chlorobenzene as emitter solvent could improve the efficiency of the devices owing to its high-boiling and low-volatile, the holes and electrons can’t be fully captured by the guest to form excitons if guest doping concentration is too small,otherwise, it will accelerate quenching effect of devices. When the heat treatment temperature is lower than 110℃, the emitting layer would form a dense uniform thin film to reduce the impact of the interface and improve the charge carrier transport. In summary, when we choose chlorobenzene as solvent, the doping ratio of 12:1 and the annealing temperature of 110℃ to prepare the emitting layer, the energy transfer is full. The maximum brightness and current efficiency are 4240cd/m2 and 24cd/A respectively.Second, we also researched on the hole injection layer and the electron transport layer of the blue PhOLED. (1) PEDOT:PSS films were UV treatment, organic solvent treatment, wherein solvent treatment makes the roughness of PEDOT:PSS film decrease, reducing the impact of the interface and optimizing the balance carrier injection. While UV treatment of PEDOT:PSS film increases the roughness and interface effect. (2) We studied the influence of TPBi thickness on devices. Suitable TPBi thickness can improve the electron injecting capability, thereby improving the carrier injection balance. When the thickness of TPBi is 45nm, the maximum brightness and current efficiency are 11000 cd/m2 and 10.4 cd/A, respectively.Finally, we studied the technology of improving the light extraction efficiency of OLED devices. Two honeycomb MLAs were prepared including the micron grade and nanoscale. The result shows that nanoscale MLA transmittance is up to 89%. So, when the MLA is applied to the green OLED device, the current efficiency is increased by 56% and the highest brightness is 27500cd/m2, without affecting the peak position of the spectrum.