Abstract
The development of polymer light-emitting diodes (PLEDs) was limited by the materials. The less material merchants controlled the high efficiency polymer and it is difficult to purchase and the price is also too high to be broad around. We want to use conventional polymer (PFO) to achieve the high efficiency blue light-emitting diodes in this studies. If we did the higher efficiency blue PLED, we could use the blending system to achieve the white light. And the application is including lighting, display and backlight for LCD. There are many advantages, like low price, simple fabricating and easy to large-area in solution process. But it is still a big problem of its layer mixing at the interface. We invented a buffer-liquid technique to fabricate multi-layer devices in our laboratory. This could enhance the device performance and prevent the layer mixing. First, we did the basic experiments to realize the characters of the materials. Then we focused on solving the defects affected by the moisture and oxygen, and searched for high molecular-weight polymers. Finally, we used buffer-liquid technique to fabricate multi-layers structure, including hole-transport layer and electron-transport layer. And we made more stable devices of different materials by using this new method. The efficiency increased form 0.8 cd/A to 3.8 cd/A. We could achieve the luminance of 8000 Cd/m2 and the external quantum efficiency of 3.99%, which is close to the maxima value. We fabricated the high efficiency LED by conventional materials compared to the materials difficult to get. Then we want to improve the lifetime of the PLEDs. And it is still continuing.