Nanoengineering of organic semiconductors for light-emitting diodes: control of charge transport

The effect of intermolecular interactions on the properties of organic semiconductors is investigated using a family of conjugated dendrimers as model systems. Increasing the amount of branching, or generation number, of these molecules reduces the degree of interaction between the chromophores. The effect of this on both photophysical and charge transporting properties is reported. It is found that an increase in generation gives rise to a reduction in the red tail emission of the dendrimer. Time of flight measurements show a slowing of charge transport with increasing generation, which is found to be related to the films becoming more insulating. The results show that dendrimer generation provides an elegant way of controlling intermolecular interactions. (C) 2001 Elsevier Science B.V. All rights reserved.