On the importance of the MIS junction to the photovoltaic properties of ITO/TPD/Alq3/Al electroluminescent devices

Abstract

Organic electroluminescent devices with an ITO/TPD/Alq3/Al structure are fabricated and tested for their photovoltaic properties. To produce an open-circuit photovoltage, a conditioning is required. Here, the conditioning is exposing the device to air for a short duration. Without this conditioning, the device produces a short-circuit photocurrent with practically no open-circuit photovoltage. Calculations and fits to the photovoltaic data show that this observation could be attributed to the formation of a metal–insulator–semiconductor junction between the Alq3 and the Al, where an insulating layer is created by this conditioning.