Performance of organic light emitting diodes with MoO3 and PEDOT:PSS as double hole injection layers

Abstract

The carrier injection capability of organic light emitting diodes (OLED) has a big influence on its performance such as the brightness and efficiency. Poly(3,4- ethylenedioxythiophene): poly(styrenesulfonate) (PEDOT: PSS) is the most commonly used hole injection material in OLED. However, PEDOT: PSS is hygroscopic and acidic, so it will corrode the ITO electrode and deteriorate the long-term performance of the device. In this paper, a P-type metal oxide- MoO3 is introduced between ITO and PEDOT:PSS by thermal evaporation, and MoO3 films of different thicknesses are made to explore the influence of MoO3 thickness on device performance. Studies show that the introduction of MoO3 not only enhances the hole injection capability, but also acts as a buffer layer between ITO and PEDOT:PSS to prevent the acidic and hygroscopic PEDOT:PSS from corroding the electrode. The MoO3/PEDOT:PSS double hole injection layer improves the efficiency and stability of the device.