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In Situ Spectroelectrochemical Studies on Ladder‐Type Oligomers in Solution and the Solid State
Author(s) -
Rapta Peter,
Schulte Niels,
Schlüter A. Dieter,
Dunsch Lothar
Publication year - 2006
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.200500955
Subject(s) - delocalized electron , alkyl , photochemistry , electrochemistry , fluorene , redox , homo/lumo , chemistry , doping , band gap , oligomer , materials science , molecule , polymer chemistry , polymer , electrode , organic chemistry , optoelectronics
A series of thermally stable fluoranthenopyracylene oligomers with extended π conjugation were studied by in situ ESR‐UV/Vis/NIR spectroelectrochemistry with respect to their application in devices such as organic light‐emitting diodes and field‐effect transistors. The oligomers are both soluble in o ‐dichlorobenzene and form thin films by evaporation in the temperature range of 300–500 °C in vacuum. Their electrochemical behavior was studied in reduction (n doping) and oxidation (p doping) under standard voltammetric and thin‐layer conditions. The HOMO and LUMO energies and the band gaps of all compounds under study were estimated from both electrochemical and UV/Vis/NIR spectroscopic data. The fluorene‐type oligomers A 2 – A 6 and B 2 bearing flexible alkyl chains exhibit both reversible multistep reductions and oxidations. The spectroelectrochemistry indicates substantial differences in delocalization of the positive and negative charges in these ladder‐type oligomers. The formation of doubly charged σ dimers was observed for the first time for both the radical anion and radical cation of the same molecule ( B 1 ). The redox behavior of the oligomers was studied in the solid state and in solution.