Nanomorphology in thin films of acetamide end-functionalised quaterthiophene

作者：Zeilmann Nina; Roesner Benedikt; Spaeth Andreas; Schmidt Ute; Fink Rainer H^*

来源：Thin Solid Films, 2015, 583: 108-114.

DOI：10.1016/j.tsf.2015.03.066

• Quaterthiophene
• Organic field effect transistor
• Confocal Raman microscopy
• Near edge x-ray absorption fine structure spectroscopy
• Scanning transmission x-ray microscopy

alpha,omega-Functionalised oligothiophenes are promising materials for organic field effect transistors due to their high degree of molecular ordering, crystallinity and pi-pi stacking. We employ several complementary microspectroscopic probes to investigate the formation of thermally evaporated films of 5,5'''-bis(N-acetamido-2- ethyl)-2,2': 5',2 '':5 '',2''' quaterthiophene on inert substrates. These films were found to grow in amixed fashion, featuring layer-by-layer domains with thicknesses of several monolayers and needle-shaped three-dimensional crystals. Detailed analysis of atomic force microscopy (AFM) and photoluminescence microscopy reveals the micro-and nanomorphology of the films. Linear dichroism in the near edge x-ray absorption fine structure and polarisation-dependent laser excitation corroborate the findings of AFM, i.e., upright standing molecules in the multilayer regime. The shape of the 3-dimensional crystallites and multilayer domains indicates strongly anisotropic growth favoured by the herringbone-arrangement of the thiophene moieties and additional stabilisation by hydrogen bonding of the acetamide end groups.

• 出版日期2015-5-29