Thin Film Transistors

In this chapter, we consider the only exclusively electronic device pursued in organic electronics: the organic thin film transistor (OTFT). The discussion begins by describing the basic architectures and functionality of OTFTs, followed by considering their operating principles based on the gradual channel approximation that simulates the transfer characteristics of most OTFTs with reasonable accuracy. Essential operating characteristics beyond their transfer functions, including dynamic range, frequency response, and noise, conclude the discussion. Several common OTFT architectures such as back-gated, ambipolar, and complementary logic devices are introduced This is followed by a section on materials and morphologies used in p- and n-channel transistors with gate geometries as small as 1 μm. After a discussion of the stability of OTFTs, the chapter ends with a description of several potential applications such as in wearable electronics and medical devices whose ultrathin form factors are nearly imperceptible to the user. Furthermore, they can fulfill needs in the diverse and large sensor markets.