title: Side chain variations on a series of dicyanovinyl-terthiophenes: a photoinduced absorption study.
abstract: We characterize a series of dicyanovinyl-terthiophenes with different alkyl side chains. Variations of side chain substitution patterns and length mainly affect the morphology of the evaporated thin films, which in turn sensitively influences properties like absorption, energy levels, and thin film roughness. To investigate changes in transfer processes between electron donor (D) and acceptor (A) molecules due to side chain variations, we use photoinduced absorption spectroscopy (PIA). PIA probes the long-living photoexcited species at the D-A interface: triplet excitons, cations, and anions. For a blend layer of dicyanovinyl-terthiophene and the electron acceptor fullerene C(60), an energy transfer via the singlet and triplet manifold of C(60) occurs. The recombination dynamics of the triplet excitons reveal two components that differ in their lifetime and generation rate by 1 order of magnitude. By comparing the dynamics of triplet excitons in neat and blend layers, we estimate the energy transfer efficiency in dependence of the type of side chain. The compound with methyl side chains shows remarkable properties regarding thin film absorption, surface roughness, and energy transfer efficiency, which we attribute to the specific nanomorphology of the thin film.
authors: Institut für Angewandte Photophysik, Technische Universität Dresden, D-01062 Dresden, Germany. hannah.ziehlke@iapp.de
authors: Hannah
authors: H
authors: Ziehlke
authors: Roland
authors: R
authors: Fitzner
authors: Christian
authors: C
authors: Koerner
authors: Roland
authors: R
authors: Gresser
authors: Egon
authors: E
authors: Reinold
authors: Peter
authors: P
authors: Bäuerle
authors: Karl
authors: K
authors: Leo
authors: Moritz K
authors: MK
authors: Riede
mesh_terms: D037741:Fullerenes / Q000737:chemistry; D015394:Molecular Structure; D009570:Nitriles / Q000737:chemistry*; D010316:Particle Size; D010777:Photochemistry; D013057:Spectrum Analysis; D013237:Stereoisomerism; D013499:Surface Properties; D013876:Thiophenes / Q000138:chemical synthesis / Q000737:chemistry*
chemical_list: D037741:Fullerenes; D009570:Nitriles; D013876:Thiophenes; C019101:alpha-terthienyl; C069837:fullerene C60