Speed World Record for Organic Transistors

Organic/polymer transistors can enable the fabrication of large-area mechanically-flexible electronic circuits and systems. In this regard, thermal evaporation through low-resolution shadow masks is a promising technological solution for the low-cost mass production of flexible circuits.

However, organic devices are inherently temperature sensitive due to the strong temperature dependence of their charge carrier mobility, suffer from low thermal conductivity of plastic substrates, and are slow due to the low charge carrier mobility and long channel length.

In a recent work published in Scientific Reports, researchers from the Chair for Circuit Design and Network Theory (CCN), and the Integrated Center for Applied Physics and Photonic Materials (IAPP) of the TU-Dresden studied vertical organic transistors with physical channel length of 200 nm based on carbon C₆₀ molecule and reported an advanced device characterization circuit that can within around ten microseconds simultaneously apply an accurate large-signal pulse bias and a small-signal sinusoidal excitation to the transistor and measure many high-frequency parameters. This characterization method significantly reduces the junction self-heating and therefore provides data at a known junction temperature more accurate for developing device models. They also demonstrated a new world record for the speed of organic transistors by achieving a transit frequency of 40 MHz. More technical details can be found in the published open-access paper:

B. K.-Boroujeni, M. P. Klinger, A. Fischer, H. Kleemann, K. Leo, and F. Ellinger, “A Pulse-Biasing Small-Signal Measurement Technique Enabling 40 MHz Operation of Organic Transistors,” Scientific Reports, vol. 8, article number 7643, May 2018. https://www.nature.com/articles/s41598-018-26008-0.

The results of this study pave the way for the integration of high-frequency functionalities into flexible organic circuits, such as long-distance wireless communication and switching power converters.

This study was funded by the German Research Foundation (DFG) under the priority programme FFLexCom; organic/polymer path of the cfaed cluster of excellence; and HFOE and EFOD projects.