Vertical type organic light emitting device using thin-film ZnO electrode

We propose a new type organic light emitting transistor (OLET) combining static induction transistor (SIT) with double hetero junction type organic light emitting diodes (OLED) using n-type zinc oxide (ZnO) films which works as a transparent and electron injection layer. The device characteristics of newly developed OLED and ZnO-SIT showed relatively high luminance of about 500 cd/m2 at 7.6 mA/cm2 and is able to control by gate voltage as low as 1 V, respectively. The crystal structure of the ZnO films as a function of Ar/O2 flow ratio and the basic characteristics of the OLET depending on the ZnO sputtering conditions are investigated. The results obtained here show that the OLET with using ZnO film is a suitable element for flexible sheet displays.