In this paper, we review recent progress in the understanding of insulator/semiconductor interfaces in organic field-effect transistors (OFETs). We would like to emphasize that the choice of gate insulator is as important for high-quality OFET devices as the semiconductor itself, especially because of the unique transport mechanisms operating in them. To date researchers have explored numerous organic and inorganic insulator materials, some of them designed to improve the morphology of the organic semiconductor (OSC). Surface treatments, particularly on inorganic insulators, have been shown to influence significantly molecular ordering and device performance. In addition, the deposition technique used for the insulator and semiconductor layers has a further impact on the active interface. Dielectric related effects are reviewed here for a variety of polymeric and molecular semiconductors reported in the literature, with an emphasis on electronic transport. We also review in more detail experiences at Philips and the recent work at Avecia to clarify some of the interface phenomena using amorphous OSC.

In this paper, we present a new effect influencing the operation of organic field‐effect transistors resulting from the choice of gate insulator material. In a series of studies it was found that the interaction between the insulator and the semiconductor materials plays an important role in carrier transport. The insulator is not only capable of affecting the morphology of the semiconductor layer, but can also change the density of states by local polarization effects. Carrier localization is enhanced by insulators with large permittivities, due to the random dipole field present at the interface. We have investigated this effect on a number of disordered organic semiconductor materials, and show here that significant benefits are achievable by the use of low‐k dielectrics as opposed to the existing trend of increasing the permittivity for low operational voltage. We also discuss fundamental differences in the case of field‐effect transistors with band‐like semiconductors.

A double‐gate device is used to demonstrate that a blended formulation of semiconducting small molecules and a polymer matrix can provide high electrical performance within thin‐film field‐effect transistors (OTFTs) with charge carrier mobilities of greater than 2 cm2 V−1 s−1, good device‐to‐device uniformity, and the potential to fabricate devices from routine printing techniques.

Scalable circuits of organic logic and memory are realized using all-additive printing processes. A 3-bit organic complementary decoder is fabricated and used to read and write non-volatile, rewritable ferroelectric memory. The decoder-memory array is patterned by inkjet and gravure printing on flexible plastics. Simulation models for the organic transistors are developed, enabling circuit designs tolerant of the variations in printed devices. We explain the key design rules in fabrication of complex printed circuits and elucidate the performance requirements of materials and devices for reliable organic digital logic.

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