Regensburg 2022 – scientific programme

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DS: Fachverband Dünne Schichten

DS 20: Poster

DS 20.10: Poster

Wednesday, September 7, 2022, 16:00–18:00, P3

Determination of circularly polarized light-triggered chiral excitons in organic light harvesting devices — •Otgonbayar Erdene-Ochir, Dirk Hertel, and Klaus Meerholz — Chemistry Department, University of Cologne, Cologne, Germany

Organic-chiroptics have not been a focus of the research area due to the trace amount of circular dichroism (CD) nature has provided in most chiral molecules. However, aggregation of chiral prolinol functionalized squaraine offers giant intrinsic CD behavior. The CD effect is related not only to the difference of left- and right-handed circularly polarized (CP) light absorption for the organic chiral molecule, but also associated with their excitonic nature based on the formation of molecular aggregates. This work discusses the determination of the selective chiral excitons via direct right- and left-handed CP laser radiation. The enantiomer of squaraine derivative (S,S)-ProSQ-C16 is a strongly CD-active material featuring maximum absorbance at ca. 780 nm after thermal annealing of a thin film. We introduced (S,S)-ProSQ-C16 as a p-type active material in a planar heterojunction (PHJ) and bulk heterojunction (BHJ) blend for the photovoltaic devices, together with the fullerenes C60 and PCBM as acceptors, respectively. We used normal-incident transmission Mueller Matrix method to determine the intrinsic CD effects of the thin film. An electronic characterization of the chiral exciton within the PHJ and BHJ systems are quantified. The efficiency of the chiroptical response is estimated by the dissymmetry factor. A systematic correlation between optical and electronic dissymmetry factors will be discussed.