Recently, organic light-emitting diodes (OLEDs) have attracted broad attention and intensive study due to their potential applications for flat-panel display and solid-state lighting. How to prepare electrodes with required electrical and optical properties is one of the major technical issues associated with the OLED structures development to obtain high-performance OLED displays....[ Read more ]

Recently, organic light-emitting diodes (OLEDs) have attracted broad attention and intensive study due to their potential applications for flat-panel display and solid-state lighting. How to prepare electrodes with required electrical and optical properties is one of the major technical issues associated with the OLED structures development to obtain high-performance OLED displays.

In this thesis, firstly, for better understanding and efficient optimization of the OLED devices, an electrical model based on one-dimension time-independent drift-diffusion model is developed to simulate the electrical process of OLED operation.

Poly-Si is proposed as an effective anode of the bottom-emitting OLEDs to simplify the fabrication process of the poly-Si TFT based active-matrix OLED (AMOLED) display and different modification methods are introduced for this novel anode. The devices with poly-Si as anode show good electroluminescent (EL) characteristics in comparison with devices using ITO as the anode.

Further more, the reflective bottom electrodes and semi-transparent top electrodes for conventional and inverted top-emitting OLEDs have been developed and investigated. High efficiency electrophosphorescent top-emitting OLED using the developed electrode has been fabricated. The device shows a maximum current efficiency of 88 cd/A and a peak power efficiency of 67 lm/W, which are much greater than those (56 cd/A and 44 lm/W) obtained from the corresponding ITO-based bottom-emitting device.

Finally, high-performance top-emitting WOLED using reflective bottom anode and semi-transparent top-cathode is realized by careful optical structure optimization. This WOLED shows a maximum external quantum efficiency of 9.1% and a power efficiency of 12.8 lm/W. In addition, a broadband white emission with very weak angle dependence was obtained. These characteristics are competitive with those of the bottom-emitting WOLED fabricated using the same organic multi-layers.