Two university research teams have worked together to produce the world’s fastest thin-film organic transistors, proving that this experimental technology has the potential to achieve the performance needed for high-resolution television screens and similar electronic devices.
For years engineers the world over have been trying to use inexpensive, carbon-rich molecules and plastics to create organic semiconductors capable of performing electronic operations at something approaching the speed of costlier technologies based on silicon. The term “organic” was originally confined to compounds produced by living organisms but now extended to include synthetic substances based on carbons and includes plastics.
Ref: Ultra-high mobility transparent organic thin film transistors grown by an off-centre spin-coating method. Nature Communications (8 January 2014) | DOI: 10.1038/ncomms4005 (Open Access)
Organic semiconductors with higher carrier mobility and better transparency have been actively pursued for numerous applications, such as flat-panel display backplane and sensor arrays. The carrier mobility is an important figure of merit and is sensitively influenced by the crystallinity and the molecular arrangement in a crystal lattice. Here we describe the growth of a highly aligned meta-stable structure of 2,7-dioctylbenzothieno[3,2-b]benzothiophene (C8-BTBT) from a blended solution of C8-BTBT and polystyrene by using a novel off-centre spin-coating method. Combined with a vertical phase separation of the blend, the highly aligned, meta-stable C8-BTBT films provide a significantly increased thin film transistor hole mobility up to 43 cm2 Vs−1 (25 cm2 Vs−1 on average), which is the highest value reported to date for all organic molecules. The resulting transistors show high transparency of >90% over the visible spectrum, indicating their potential for transparent, high-performance organic electronics.