Degradation of PEDOT:PSS hole injection layers by electrons in organic light emitting devices

Abstract

Abstract The degradation of PEDOT:PSS (poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) hole injection layers (HILs) under electrical bias and its effect on the stability of organic light emitting devices (OLEDs) during device operation is investigated. Phosphorescent and fluorescent OLEDs with common hole transport layers (HTLs) and PEDOT:PSS, MoO3 and PEDOT:PSS/MoO3 HILs, and hole-only devices with the same HILs and HTLs are examined. Results show that PEDOT:PSS HILs are susceptible to degradation by electrons; a mechanism that can accelerate device failure. Minimizing electron leakage to the PEDOT:PSS/HTL interface is found to play a key role in maintaining the stability of these devices. Results also show that degradation by excitons and hole accumulation at the PEDOT:PSS/HTL interface have a much less significant effect. The findings provide key insights for improved device design for OLEDs utilizing PEDOT:PSS HILs.