Organic Field Effect Transistor Using Pentacene Single Crystals Grown by a Liquid-Phase Crystallization Process
Original entry: William Bonificio, AP 225, Fall 2009
Organic Field Effect Transistor Using Pentacene Single Crystals Grown by a Liquid-Phase Crystallization Process. Yasuo Kimura, Michio Niwano, Naohiko Ikuma, Kenichi Goushi, Kingo Itaya. Langmuir 2009 25 (9), 4861-4863
Soft matter keywords
Liquid-Phase Crystallization, Pentazene, Organic Field Effect Transistor (OFET), Pentacene, Tricholorbenzene.
The purpose of this study was to investigate a different fabrication technique for creating single crystals of pentacene to be used for organic field effect transistors. The liquid-phase crystallization process creates single crystals by evaporating pentacene in solution, then precipitating it as a single crystal. The pentacene crystals formed by this method then had their semiconducting properties measured and these properties were compared to pentacene crystals grown using different methods.
Soft matter discussion
Organic field effect transistors (OFETs) have many favorable properties over current field effect transistors (FETs). The most popular OFET, due to its optimal electronic properties derived from its delocalized pi bond, is pentacene. These properties however, are degraded by the existence of grain boundaries in polycrystalline pentacene as a result of the reduced mobility in charge carriers. Therefore, single crystals of pentacene are primarily used. The most popular way of synthesizing the single crystalline pentacene is currently by physical vapor deposition.
An alternative method of creating pentacene single crystals is by liquid-phase crystallization. In this process pentacene dissolved in trichlorobenzene is purified via various methods. Then the pentacene is evaporated and very slowly cooled so that precipitation occurs as a single crystal. In fact, in this experiment the pentacene was heated to 200C, then cooled at 0.1C per hour. The phase change from solute, to gas, to solid single crystal is clearly applicable to the soft matter discussion.