Picosecond Laser Induced Photophysical Processes of Thiophene Oligomers

Dieter Grebner, Matthias Helbig, and Sabine Rentsch 

Within the conjugated polymers polythiophene is an important material for future technical applications, e. g. for LEDs, electronic devices, or optical switches [1]. In this context studies of light induced processes are of interest, especially details of the degradation of electronic energy within the ultrashort time scale of picoseconds and sub-picoseconds. 

These processes mostly proceed within the molecules and are presteps to transfer processes of energy or electrons between different molecules, which dominate in technical devices. A polymer molecule with about 100 monomer units is a complex system which corresponds to an inhomogeneous distribution of subsystems with slightly different optical properties, called effective conjugated segments within a polymer chain. 

In this study we had the opportunity to investigate systematically the spectroscopic properties of a series of hnear thiophene oligomers [2-8]. The idea was to observe the fast hght induced processes of these small constituents of a polymer as starting point for deeper understanding of processes in the polymer itself 

We studied ohgothiophenes from 2 to 6 monomers in dilute solution because in this case the interaction between the ohgomer molecules is negligible. Therefore the dominance of intramolecular processes was to be expected. 

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Picosecond Laser Induced Photophysical Processes of Thiophene Oligomers... 

Picosecond Laser Induced Photophysical Processes of Thiophene Oligomers Table 17.1 Decay time tai of the transient absorption A1 and fluorescence decay time %s for nT in dioxane. 

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