Challenging Problems in Organic Electronics
George Malliaras
Materials Science and Engineering, Cornell University
During the past two decades dramatic advances have been achieved in the performance of organic semiconductor devices. Light emitting diodes, transistors, solar cells, and several other devices can now be fabricated from organic semiconductors and are at various stages of commercialization. This fast-paced progress, which highlights the technological potential of soft materials, is largely a result of advances in our ability to deposit and pattern high quality organic films.
I will discuss two materials systems that are of high importance to organic electronics. The first one is ionic transition metal complexes, which are being developed for applications in electroluminescent devices. Films from these materials are deposited from solution, and are usually sandwiched between two metal electrodes to form an electroluminescent device. Their device physics is very interesting, as in addition to being semiconductors, they also show ionic conductivity. I will discuss major open questions in this field.
The second class of materials is small organic molecules such as pentacene. These materials are deposited using vacuum sublimation to yield polycrystalline films which show reasonably high mobility. Their main application is in thin film transistors and photovoltaics. I will discuss the evolution of structure and morphology of these materials and outline open questions to be addressed with x-ray techniques.
