High-Resolution Near-Field Optical Investigation of Crystalline Domains in Oligomeric PQT-12 Thin Films

Autor: Markus Breusing, Thomas Fischer, Dieter Neher, Patrick Pingel, Sergei Kuehn, Joachim Stumpe, Thomas Elsaesser
Přispěvatelé: Publica
Rok vydání: 2011
Předmět:
Zdroj: Advanced Functional Materials. 21:860-868
ISSN: 1616-301X
DOI: 10.1002/adfm.201001978
Popis: The structure and morphology on different length scales dictate both the electrical and optical properties of organic semiconductor thin fi lms. Using a combination of spectroscopic methods, including scanning near-fi eld optical microscopy, we study the domain structure and packing quality of highly crystalline thin fi lms of oligomeric PQT-12 with 100 nanometer spatial resolution. The pronounced optical anisotropy of these layers measured by polarized light microscopy facilitates the identifi cation of regions with uniform molecular orientation. We fithat a hierarchical order on three different length scales exists in these layers, made up of distinct well-ordered dichroic areas at the ten-micrometer-scale, which are sub-divided into domains with different molecular in-plane orientation. These serve as a template for the formation of smaller needle-like crystallites at the layer surface. A high degree of crystalline order is believed to be the cause of the rather high fi eld-effect mobility of these layers of 10 − 3 cm 2 V − 1 s − 1 , whereas it is limited by the presence of domain boundaries at macroscopic distances.
Databáze: OpenAIRE