Ultra-low capacitance organic thin-film transistors
July 2017
The field of organic electronics has attracted great interest from the industry within the past years. Flexible, light-weight, efficient and low-cost electronic devices such as organic light-emitting diodes or solar cells have created a growing multi-billion euro market. Organic thin-film transistors (OTFTs), however, are still suffering from various disadvantages in comparison to their inorganic counterparts and hence all-organic flexible electronics are not ready for applications yet.
One of the main target applications for organic thin-film transistors is to use them for the backplane in flexible active matrix organic light-emitting diode displays (AMOLED). The performance of current organic transistors is sufficient for this application in many aspects (charge carrier mobility, on/off ratio and stability). However, focusing on the requirements concerning the dynamic OTFT response, state-of-the-art organic transistors suffer from high parasitic capacitances which slow down the dynamic response and lead to undesired power losses in the AMOLED backplane. Researchers at the IAPP are developing ultra-low capacitance OTFTs using a self-alignment technique. In this way, the parasitic capacitance can be reduced significantly leading to a large increase of the TFTs cut-off frequency (>20MHz). However, the adoption of this self-alignment technique (which is heavily used in silicon technology) to organic semiconductors requires the development of new fabrication methods which have to be compatible to organic semiconductor materials.
The aim of this work is to demonstrate and characterize a self-aligned organic thin-film transistor based on common n- and p-type organic semiconductor materials. Furthermore, different fabrication techniques will be evaluated concerning the TFT performance and reliability. In particular, we would like to understand whether there is a compromise between charge carrier mobility and device capacitance. The ultimate target of this project is to build a self-aligned organic TFT with dimensions as typically used in AMOLED displays, set-up a characterization system and measure the device capacitance which is expected to be <1fF.
The IAPP is a place where more than 120 physicists, chemists and engineers are working together on all virtually topics related to organic electronics – fundamentals and applications. Hence, the IAPP provides a perfect platform for the application to interact with other scientists in order to get a broad overview on other research topics on organic electronics.
Contact person:
© Kai Schmidt/IAP
Dr. Hans Kleemann
ODS group (Organic Devices and Structures)
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