Conjugated polymers are of considerable current interest because of their semi-conducting and light-emitting properties. These properties, combined with their relatively low cost and good processability as compared to inorganic semiconductors, make them attractive candidates for application in plastic electronic devices. Conjugated polymers are being considered for application as the semi-conducting layer in low-cost field-effect transistors (FETs) for the fabrication of flexible or disposable electronic devices. A second application using the light-emitting properties of conjugated polymers is as an emissive layer in light emitting diodes (LEDs) and large area displays. The third application that is being considered is the use of conjugated polymers as the light absorbing layer in photovoltaic devices. Finally, the fourth possible application is the use of conjugated polymers is as molecular wires in single molecule electronics.
All of these applications critically rely on the ability of the conjugated polymers to transport charges. A thorough understanding of the properties of charge carriers and their mobility is therefore of obvious importance. Some of the applications involve electronically excited states of conjugated polymers. In LEDs the lowest singlet excited state is the emissive state, while in photovoltaic devices the excited state is the primarily formed species. Therefore it is also of interest to study the properties of conjugated polymers or oligomers in their electronically excited state.
This publication describes a combined experimental and theoretical study of the opto-electronic properties of isolated conjugated polymers in dilute solution.