Bert de Boer

During the last decade the field of polymer photovoltaics has seen a tremendous improvement in both device efficiency and understanding of the underlying physical processes. One has come to a point in which the prototypical large bandgap material system P3HT:PCBM is nearing optimal device performance. In order to enhance efficiencies even further, research activities for new materials are needed with better aligned energy levels. One interesting approach is by narrowing the donor bandgap to enhance light absorption. Recent developments on small band gap (<2.0 eV) materials for photovoltaic applications are reviewed. First, an introduction is given regarding the processes governing the exciton dissociation, charge transport requirements, energy level engineering of both donor and acceptor materials, and other parameters determining the photovoltaic performance. The focus is on polymeric donor materials, which are subdivided by the type of monomeric units that constitute the backbone. Finally, the synthetic methods and conditions, processing of the devices, and the device performances are summarized.

A memory functionality is a prerequisite for many applications of electronic devices. Organic nonvolatile memory devices based on ferroelectricity are a promising approach toward the development of a low-cost memory technology. In this Review Article we discuss the latest developments in this area with a focus on three of the most important device concepts: ferroelectric capacitors, field-effect transistors, and diodes. Integration of these devices into larger memory arrays is also discussed.

Although research on molecular electronics has drawn increasingly more attention in the last decade, the large spread in obtained results for the conduction rescaled to a single molecule indicates a strong dependence of the measured data on the experimental testbed used. We subdivided a generalized metal-molecule-metal junction into different components and discuss their influence on electrical transport measurements of a single organic molecule or an assembly of molecules. By relating the advantages and disadvantages of different experimental testbeds to the more general view of a molecular junction, we strive to explain the discrepancies between the obtained results on molecular conduction. The reported results on molecular conduction of molecules with an alkane backbone can be categorized into three groups with different resistance values, depending on the device area of the molecular junction and the nature of the contacts.