Silicon dioxide buffer at anode/polymer interface for enhanced brightness and efficiency of polymer light-emitting diode

摘要

There has been recently renewed interest in improving the poor efficiency of light-emitting diodes (LED) such as organic light-emitting diodes (OLED) and polymer light-emitting diodes (PLED) [1-3]. The limited performance of existing diodes results from the fact that a device formed on a bare indium-tin-oxide (ITO) surface usually shows insufficient hole injection and poor operational stability. One previously reported improvement for this situation has involved interposing an intermediate layer between the ITO and the active layer [4-7]. The insertion of the layer generally results in a substantial increase in drive voltage because of a hole injection barrier present at the interface. However, the improvement in operational stability is insufficient, and the effectiveness of the treatment is strongly dependent on processing conditions. In order to improve the efficiency, the method of room-temperature liquid phase deposition (LPD) to deposit an ultra-thin silicon dioxide film on the ITO is employed [8-11].