| 초록 |
The light emitting properties of of organic light emitting diodes(OLEDs) are greatly dependent on the charge injection and transport layers as well as a light emitting layer. In particular, the driving voltage, luminance efficiency, and long term stability of OLEDs are closely related to charge injection and transport in the device. The charge injection and transport properties of OLEDs can be enhanced by modifying hole transport layer and electron transport layer. The use of charge transport materials with high charge mobility and low injection barrier with an anode and a metal cathode is an efficient way to get low driving voltage. The light emitting efficiency and lifetime can also be improved by optimizing the charge balance in the device. C60 has been used in solar cells because photoinduced charge transfer between C60 and conducting polymers leads to a photovoltaic effect. It has been found that the C60 can be used as a weak electron-acceptor dopant in conducting polymers, and the enhancement of photoconductivity was observed in C60/conducting polymer system. Therefore, C60 can also be used as a weak electron acceptor with aromatic amine and it can have p-doping effect in the hole transport layer. In addition, C60 has high electron mobility and it can also be used as an good electron transport material which can give low driving voltage. In this work, the role of C60 as a hole injection buffer, p-type dopant in the hole transport layer, and electron transport material will be discussed. |
