Universal high work function flexible anode for simplified ITO-free organic and perovskite light-emitting diodes with ultra-high efficiency

Flexible transparent electrode materials, including conducting polymers, silver nanowires, carbon nanotubes, and graphene, have been investigated to replace conventional brittle indium tin oxide (ITO). However, they have serious problems of low work function (WF), resulting in a high hole injection barrier to overlying semiconducting layers. Now, Tae-Woo Lee from Seoul National University in Korea and co-workers have developed ITO-free simplified organic and perovskite light-emitting diodes with high-efficiency by using a single-layered high WF polymeric anode, which can act as both an anode and a hole injection layer. Since the high WF polymeric anode make efficient hole injection to the overlying organic and perovskite semiconducting layers, they dramatically improve the device efficiencies even without any hole injection layer.