Improved injection properties of self-passivated degenerated transparent electrode for organic and perovskite light emitting devices

Abstract

Most electrode materials are either metals or transparent conductive oxides (TCOs). While metals show higher carrier transfer ability, TCOs could be the good adhesive of functional materials exhibiting better surface passivating performance. Therefore, to eliminate the limitation of either efficiency or interface stability, it comes to be a significant and challenging topic to develop an electrode with metallic conductivity and surface chemistry of oxides. Traditionally, heavy doping is a solution to increase the carrier density in TCOs, for instance, indium-doped tin oxide (ITO). However, their conductivity still shows a huge difference with metals. Thus, here we prove that a fine-designed nano-structure can show comparable carrier density with metal, while remains oxide surface. Furthermore, this homogeneous metallic super-layer shows work function changes on the contact due to an indirect alignment. By introducing the metallic layer as transparent anode in various optoelectronics, all devices exhibit better-injecting performance than ones with commercial ITO electrode. This metallic electrode demonstrates a 1.8-fold increase of current efficiency comparing to ITO as anode of organic light emitting devices and 1.3-fold increase of that in perovskite light emitting devices. These results illustrate the strategy of novel electrode structure designs to further improve the efficiency of optoelectronics.