Vertical type organic transistor for flexible sheet display

Abstract

Vertical type organic light emitting transistors (OLETs), which combined with the organic static induction transistors (OSITs) as the vertical type organic transistors and conventional organic light emitting diodes (OLEDs), are promising for flexible sheet displays. In our recent research, pentacene based OSITs fabricated on flexible plastic substrates exhibited stable electrical characteristics under bending condition. However, several problems have remained in the OSITs with low on/off ratio and low current value for use in the vertical type OLETs. This paper describes our recent efforts to improve the performance of vertical type OLETs by optimizing the device structure and organic materials used in the OSITs. Interface between organic source electrode and semiconductor is important factor to control the device operation of vertical type organic transistors. CuPc layer was inserted between ITO source electrode and pentacene film in order to improve the performance of OSITs. The results showed that both the high on/off ratio more than 103 and the high current value of larger than 40 μA were achieved. In addition, vertical type OLET and logic devices were fabricated using the OSITs for the realization of flexible sheet displays. These results exhibit that the OSITs attract attention for application in organic flexible displays.