Search

Angle-resolved photoelectron spectroscopy (ARUPS) is used to study the electronic structure and supramolecular organization of the discotic molecule deposited on graphite. The study reveals the strongly delocalized nature of the pi-electrons along the discotic stacks.

The concept of chemical potential equalization described in the framework of density functional theory has been used to rationalize the charge-transfer process. The prediction of the direction of charge transfer in this way is in good agreement with both the results of an experimental approach using XPS and the results of a theoretical approach where full quantum-mechanical calculations are performed on complexes composed of an absorbate and a metal surface model.

Low-voltage-operating organic electrochemical light-emitting cells (LECs) and transistors (OECTs) can be realized in robust device architectures, thus enabling easy manufacturing of light sources using printing tools. In an LEC, the p-n junction, located within the organic semiconductor channel, constitutes the active light-emitting element. It is established and fixated through electrochemical p- and n-doping, which are governed by charge injection from the anode and cathode, respectively. In an OECT, the electrochemical doping level along the organic semiconducting channel is controlled via the gate electrode. Here we report the merger of these two devices: the light-emitting electrochemical transistor, in which the location of the emitting p-n junction and the current level between the anode and cathode are modulated via a gate electrode. Light emission occurs at 4 V, and the emission zone can be repeatedly moved back and forth within an interelectrode gap of 500 μm by application of a 4 V gate bias. In transistor operation, the estimated on/off ratio ranges from 10 to 100 with a gate threshold voltage of -2.3 V and transconductance value between 1.4 and 3 μS. This device structure opens for new experiments tunable light sources and LECs with added electronic functionality., (© 2011 American Chemical Society)