Berlin 2012 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 2: Focus Session: Structural Ordering and Electronic Transport I (jointly with CPP)
HL 2.2: Vortrag
Montag, 26. März 2012, 10:00–10:15, ER 270
Influence of Alkyl Side Chain Length on the Self-organization of RT and Low Temperature Cast Poly(3-alkylthiophene) Thin Films — •Shabi Thankaraj Salammal1, Souren Grigorian1, Ullrich Pietsch1, Martin Brinkmann2, Navaphun Kayunkid2, Nils Koenen3, and Ullrich Scherf3 — 1University of Siegen — 2CNRS, Strasbourg — 3University of Wuppertal
An enhancement of in-plane stacking of poly(3-alkylthiophene)s (P3ATs) with decrease of alkyl side chain length has been thoroughly analyzed using X-ray and electron diffraction (ED)technique. Thin films of poly(3-pentylthiophene), poly(3-hexylthiophene), poly(3-heptylthiophene), and poly(3-octylthiophene) (P3OT) were cast at 23°C(RT) and low (-30°C) temperature. Thin films prepared using the lowest concentration (1mg/14ml) envisages that the P3OT crystallites can provide highly edge-on oriented and bigger crystallites by casting at low temperature. The X-ray and electron diffraction patterns collected for the same films shows the poor in in-plane ordering of P3AT crystallites as the side chain length increases due to the augment in steric hindrance between the alkyl side chains. It subsequently reduces the photoluminescence (PL) efficiency as well as the field effect mobility of organic field effect transistors. The reduction in cast temperature together with the reduction of alkyl side chain length is resulting three distinct PL peaks with defined linewidths. The absence of face-on oriented crystallites while casting at -30°C can be explained by the prolongation of growth time caused by the reduced evaporation of solvent (Chloroform).