Femtosecond pump-probe spectroscopy of excited states in conjugated polymers for organic electronics

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The further development of conjugated polymers for optoelectronic applications, for example organic light emitting diodes (OLEDs), field-effect transistors, organic lasers and photovoltaics requires a complete understanding of their photophysical properties. Therefore, a variety of different experimental techniques has to be applied with experiments ranging from time-resolved photoluminescence spectroscopy covering the time range from femtoseconds up to seconds, over charge carrier mobility measurements towards application and characterisation of the investigated materials in organic electronic devices. The intended research project aims for an understanding of the photophysical properties of a novel series of ladder-type conjugated polymers which are highly promising candidates for organic electronics. In particular, femtosecond pump-probe spectroscopy and photoinduced absorption (PIA) studies shall be conducted on these materials to study excited state absorption originating from singlet and triplet excitons as well as polarons (radical anions / cations), which are known to play an important role in organic electronic devices and can severely limit the applicability of conjugated polymers in organic solid state lasers. Preparation of organic electronic devices, especially feedback structures for organic solid state lasing as well as organic solar cells is planned to correlate the results of the photophysical characterisation with properties in electronic devices and to develop reliable structure-property relationships.