Hosted by: Chang-Yong Nam

In the last decade, organic electronics has promised a seemingly bright future for flexible and large area electronics. However, functional organic transistors are not realized yet due to the low carrier mobilities and downscaling issue of the organic layers. Vertical organic transistors are a viable solution to overcome these challenges because the short vertical channel can drive large output currents at low powers. In this presentation, two types of vertical organic transistors will be introduced: 1) permeable metal-base transistors (PMBTs) where a permeable metal-base is sandwiched by two semiconductor layers and 2) vertical organic Schottky barrier transistors (VOSBTs) where an organic Schottky barrier is modulated by the underlying gate electric field. In both types of transistors, a nano-porous electrode play a key role for the output current modulation. Understanding the effects of the pore size and density in the porous electrode on the modulation behavior enables the development of high gain PMBTs or VOSBTs with large current on/off ratio. A key advantage of the vertical device architecture is its direct integration with functional layers for novel sensor applications. By inserting optoelectronic, ferroelectric, or piezoelectric layers into the gate insulator of the VOSBT, a high efficiency infrared photodetector (optoelectronic VOSBT), flexible non-volatile memory (ferroelectric VOSBT), or a novel ultrasonic sensor (piezoelectric VOSBT) could be developed respectively. Further insertion of an organic light-emitting diode into the channel layer of the VOSBT resulted in novel light-emitting sensors such as infrared-to-visible up-conversion devices or ultrasonic-gated OLEDs that may enable pixel-less infrared or acoustic imaging in the future.