Study on operating lifetime of organic light emitting device

In this paper, we studied the operation lifetime of organic light emitting device (OLED) with different device structure. In our experiments, the organic materials were fixed while the thickness of the hole transport layer (HTL) and electron transport layer (ETL) were varied. We found that device lifetime was increased with increased device efficiency. That indicated the electron-hole balance is one of the key issues for longer lifetime. When the electron-hole was not balance, the "electron-rich" device had longer lifetime than that of the "hole-rich" device under the same device efficiency. That implied the cation of ETL material had great influence on the device lifetime.