title: H-aggregate analysis of P3HT thin films-Capability and limitation of photoluminescence and UV/Vis spectroscopy.
abstract: Polymer morphology and aggregation play an essential role for efficient charge carrier transport and charge separation in polymer-based electronic devices. It is a common method to apply the H-aggregate model to UV/Vis or photoluminescence spectra in order to analyze polymer aggregation. In this work we present strategies to obtain reliable and conclusive information on polymer aggregation and morphology based on the application of an H-aggregate analysis on UV/Vis and photoluminescence spectra. We demonstrate, with P3HT as model system, that thickness dependent reflection behavior can lead to misinterpretation of UV/Vis spectra within the H-aggregate model. Values for the exciton bandwidth can deviate by a factor of two for polymer thicknesses below 150 nm. In contrast, photoluminescence spectra are found to be a reliable basis for characterization of polymer aggregation due to their weaker dependence on the wavelength dependent refractive index of the polymer. We demonstrate this by studying the influence of surface characteristics on polymer aggregation for spin-coated thin-films that are commonly used in organic and hybrid solar cells.
authors: Department of Physics, University of Konstanz, POB 680, 78457 Konstanz, Germany.
authors: Philipp
authors: P
authors: Ehrenreich
authors: Department of Physics, University of Konstanz, POB 680, 78457 Konstanz, Germany.
authors: Susanne T
authors: ST
authors: Birkhold
authors: Department of Physics, University of Konstanz, POB 680, 78457 Konstanz, Germany.
authors: Eugen
authors: E
authors: Zimmermann
authors: Department of Physics, University of Konstanz, POB 680, 78457 Konstanz, Germany.
authors: Hao
authors: H
authors: Hu
authors: Department of Physics, University of Konstanz, POB 680, 78457 Konstanz, Germany.
authors: Kwang-Dae
authors: KD
authors: Kim
authors: Department of Physics, University of Konstanz, POB 680, 78457 Konstanz, Germany.
authors: Jonas
authors: J
authors: Weickert
authors: Department of Physics, University of Konstanz, POB 680, 78457 Konstanz, Germany.
authors: Thomas
authors: T
authors: Pfadler
authors: Department of Physics, University of Konstanz, POB 680, 78457 Konstanz, Germany.
authors: Lukas
authors: L
authors: Schmidt-Mende