The chemical diversity of organic semiconductors coupled with the kinetic nature of film formation make it challenging to tune the structure of active-layer thin films in organic electronics across multiple length scales. We review techniques to tune aspects of film structure within a framework that accounts for the competition between the time available for structural development and the time required by the organic semiconductors to order, defined by a dimensionless time, τ, that describes the ratio of these two quantities. By considering these two competing time scales, we propose general guidelines to tune the film structure accordingly.

The field of organic electronics is entering its commercial phase. The recent market introduction of the first prototypes based on organic transistors fabricated from solution is set to augment the existing market presence of organic light-emitting diode applications. Organic photovoltaic products are not far behind. In this article, we provide a brief overview of these devices, with our main focus being organic transistor applications. In particular, we examine some of the key performance requirements for working devices. We also review some of the important advances in semiconductor design and device fabrication techniques and discuss some of the technical challenges that remain in the optimization of next-generation products.

Lamination of metal-coated elastomeric stamps against thin films of electroactive organics provides non-invasive, high resolution electrical contacts for investigations of charge transport in these materials. This approach uses the features of relief on the stamps to define, with nanometer resolution, the geometry and separation of electrodes that are formed by uniform evaporation of a thin metal film onto the stamp. Soft, room temperature contact of an element of this type with an organic semiconductor film on a gate dielectric and a gate yields a high performance top contact transistor with source/drain electrodes supported by the stamp. We review here our use of this approach to study the electrical properties of the organic semiconductor pentacene in thin film transistors structures. We also introduce a method for using the same techniques and structures to probe transport through organic monolayers.

Lamination of metal-coated elastomeric stamps against thin films of electroactive organics provides non-invasive, high resolution electrical contacts for investigations of charge transport in these materials. This approach uses the features of relief on the stamps to define, with nanometer resolution, the geometry and separation of electrodes that are formed by uniform evaporation of a thin metal film onto the stamp. Soft, room temperature contact of an element of this type with an organic semiconductor film on a gate dielectric and a gate yields a high performance top contact transistor with source/drain electrodes supported by the stamp. We review here our use of this approach to study the electrical properties of the organic semiconductor pentacene in thin film transistors structures. We also introduce a method for using the same techniques and structures to probe transport through organic monolayers.

Organic electronic systems offer the advantage of low weight and flexibility at potentially lower cost. Although the fabrication of functioning plastic transistors using approaches such as ink jet, lithography and stamping has been described i1–3, chemically compatible materials that allow for the sequential application of liquid layers is a technical barrier. Material issues maybe the Achilles heel of ultimately printing organic electronic devices as newspapers today, at high speeds and in a reel to reel process. We introduce a novel process–thermal transfer–a non-lithographic technique that enables printing multiple, successive layers via a dry additive process. This method is capable of patterning a range of organic materials at high speed over large areas with micron size resolution and excellent electrical performance. Such a dry, potentially reel-to-reel printing method may provide a practical route to realizing the expected benefits of plastics for electronics. We illustrate the viability of thermal transfer and the ability to develop suitable printable organics conductors by fabricating a functioning 4000 cm2 transistor array.