| 초록 |
Organic amorphous films are important components in organic devices such as organic light-emitting diodes (OLEDs). Recently, horizontally oriented amorphous thin films have been used in OLEDs, making use of their high-performance electrical characteristics. In this study, we further synthesized novel disk-like molecular structures of B-DDP, T-DDP and BT-DDP, aimed for the enhancement of horizontal orientation by introduction of two-dimensional planar structures having rather intense π-π interaction, leading to low driving voltage in OLEDs. The order of orientation parameter of S is BT-DDP(0.23)＜T-DDP(0.18)＜B-DDP(0.11)＜α-NPD(0.01), indicating that BT-DDP shows superior horizontal orientation. In the OLED characteristics, compared with α-NPD, the use of DDP derivatives resulted in lower driving voltage. We clarified that the ITO/BT-DDP interface provides small energy barrier for hole injection probably due to the planar orientation of BT-DDP on an ITO surface. |
