WFU Physics Colloquium

TITLE: Alignment of Polymer Semiconductors to Probe Charge Transport Behavior

SPEAKER: Professor Brendan O'Connor,

TIME: Wednesday September 28, 2011 at 4:00 PM

PLACE: Room 101 Olin Physical Laboratory

Transistors are the building blocks of electronic devices and are ubiquitous in our lives. For many low-speed and large area electronics applications, these transistors are typically based on hydrogenated amorphous silicon. For example, in active matrix liquid crystal displays (AMLCDs), amorphous silicon based transistors are used to control each individual pixel. In 2009 more than 1 billion AMLCDs were produced with a total area of about 10⁸ m² and a total value of $80 billion.[1] For these low-speed applications, there is growing interest in using organic semiconductor based transistors. Unlike amorphous silicon, organic materials can be deposited at low temperatures onto low-cost plastic substrates. In addition, the organic semiconductors are van der Waals bonded allowing for highly flexible devices. While organic thin film transistor (OTFT) performance has been making great progress over the past 10 years, understanding charge transport in these devices has been a challenge, particularly for devices employing polymer semiconductors.

In this talk, relationships between polymer thin film morphology and charge transport behavior in OTFTs will be discussed. The talk will cover various processing methods used to manipulate the polymer film, and methods to characterize the resulting morphology and electronic properties. Particular emphasis will be placed on aligning the polymer chains through stretching the polymer film. It will be shown that by aligning the polymer chains, several novel insights into charge transport behavior in semicrystalline polymer semiconductors can be made, improving our understanding of charge transport in these materials.

[1] Klauk, H., Organic Thin Film Transistors. Chem. Soc. Rev., 39, 2643, 2010.