Electronic devices go organic
For decades, inorganic semiconductors have been studied in a huge variety of electronic devices. The use of organic materials as substitutes for inorganic semiconductors has shown that it is possible to fabricate devices based on similar principles. However, competing with established inorganic counterparts will need more than copying the underlying mechanisms – it is necessary to exploit the full advantages of molecular structures. This was the aim of the EU-funded project MULTITUDES (Μultifunctional organic electronics through nanoscale controlled bottom-up tailoring of interfaces: An Intra-European fellowship for career development). Chemical design of self-assembled monolayers (SAMs) has been shown to be a successful route to modulate key properties of surfaces and interfaces for electronic applications. Within MULTITUDES the interplay between chemical design and work function of SAM-covered gold electrodes has been investigated, and the importance of fine-tuning electrode properties to optimise charge injection into organic field effect transistors (OFETs) was highlighted. By exploiting the light sensitivity of specific chemisorbed molecules, it was shown that it is possible to optically modify the work function of SAM-covered electrodes. Such changes were monitored both experimentally and by quantum-chemical calculations and allowed development of an optically switchable transistor. Making use of a new method developed within this project different SAMs were assembled on adjacent electrodes enabling the independent tuning of the electrode properties. In particular, the integration of photoswitchable SAMs responding at diverse wavelengths made it possible to fabricate a multi-wavelength optically switchable transistor. The new knowledge of SAM formation acquired by the MULTITUDES project is expected to play a key role in the optimisation of organic electronic devices. Furthermore, electrodes covered with SAMs can be transformed from passive components to a source of multifunctionality, opening the way to new concepts in the design of organic logic gates, memories and sensors.
Keywords
Electronic devices, inorganic semiconductors, self-assembled monolayers, organic field-effect transistors, gold electrodes
