Arthur Markus Anton
University of Leipzig, Germany
Title: IR TMOA-Infrared Transition Moment Orientational Analysis as a Valuable Method to Determine the Spatial Orientation and Order of Distinct Subunits in Polymeric Systems
Biography
Biography: Arthur Markus Anton
Abstract
Infrared Transition Moment Orientational Analysis as a Valuable Method to Determine the Spatial Orientation and Order of Distinct Subunits in Polymeric Systems (IR TMOA): On the basis of their versatile usage in organic field effect transistors or solar cells in conjunction with their soft matter properties, such as flexibility and convenient adaption of shape, donor/acceptor conjugated copolymers have received great attention as a fascinating class of materials [1]. In order to tailor the macroscopic properties of their films, a detailed understanding of the corresponding molecular organization is required. For that reason, the method of Infrared Transition Moment Orientational Analysis (IR-TMOA, Fig. 1) is employed to elucidate the spatial orientation and order in thin layers of P(NDI2OD-T2) [2,3]. The spectral absorbance of selected bands is evaluated in dependence on the inclination (ïŠ) and the polarization (ïª) of the incoming light, which allows to examine the absorption tensor for the distinct structural moieties independently. As a result, the orientation of atomistic planes defined by the naphthalenediimide (NDI, blue) and bithiophene (T2, yellow) subunits is determined relative to the substrate (ï‘), and hence, relative to each other (ï£): whereas in spin coated films the T2 units exhibit a preferential face on or edge on alignment conditioned by the solvent, the NDI parts are not affected [2]. Furthermore, pronounced in-plane anisotropy of the NDI segments is evident in a 150 nm thin film demonstrating self assembled long range order of the polymer chains, even though they are spin coated from solution [3]