135831-08-2Relevant articles and documents
Approaching the Integer-Charge Transfer Regime in Molecularly Doped Oligothiophenes by Efficient Decarboxylative Cross-Coupling
Forgione, Pat,Hase, Hannes,Liu, Jiang Tian,Salzmann, Ingo,Taylor, Sarah
, p. 7146 - 7153 (2020/03/23)
A library of symmetrical linear oligothiophene was prepared employing decarboxylative cross-coupling reaction as the key transformation. Thiophene potassium carboxylate salts were used as cross-coupling partners without the need of co-catalyst, base, or additives. This method demonstrates complete chemoselectivity and is a comprehensive greener approach compared to the existing methods. The modularity of this approach is demonstrated with the preparation of discreet oligothiophenes with up to 10 thiophene repeat units. Symmetrical oligothiophenes are prototypical organic semiconductors where their molecular electrical doping as a function of the chain length can be assessed spectroscopically. An oligothiophene critical length for integer charge transfer was observed to be 10 thiophene units, highlighting the potential use of discrete oligothiophenes as doped conduction or injection layers in organic electronics applications.
Efficient deep-red electroluminescent donor-acceptor copolymers based on 6,7-dichloroquinoxaline
Gao, Xiang,Zhang, Yubao,Fang, Cheng,Cai, Xiang,Hu, Bin,Tu, Guoli
, p. 276 - 282 (2017/05/10)
Since the large steric hindrance caused by chlorine atoms not only suppresses the aggregation but also results in large stokes shift and low self-absorption, a series of donor-acceptor alternating copolymers based on 6,7-dichloroquinoxaline have been synthesized by modifying the structures of oligothiophenes. All the polymers have been well characterized to study the effects of the length of oligothiophenes and the steric hindrance on the optical, electronic and electroluminescent properties. It was observed that the intramolecular charge transfer absorption was weakened by steric hindrance. Unlike non-chloride analogues, prolonged conjugated length resulted in smaller bandgap, given similar steric hindrance. Deep-red emission centered at 678?nm with brightness about 1800?cd?m?2 was achieved with external quantum efficiency 1.34% using dopant/host technic.
Preparation and characterization of π-stacking quinodimethane oligothiophenes. Predicting semiconductor behavior and bandwidths from crystal structures and molecular orbital calculations
Janzen, Daron E.,Burand, Michael W.,Ewbank, Paul C.,Pappenfus, Ted M.,Higuchi, Hiroyuki,Da Silva Filho, Demetrio A.,Young, Victor G.,Bredas, Jean-Luc,Mann, Kent R.
, p. 15295 - 15308 (2007/10/03)
A series of new quinodimethane-substituted terthiophene and quaterthiophene oligomers has been investigated for comparison with a previously studied quinoid oligothiophene that has demonstrated high mobilities and ambipolar transport behavior in thin-film transistor devices. Each new quinoidal thiophene derivative shows a reversible one-electron oxidation between 0.85 and 1.32 V, a quasi-reversible one-electron second oxidation between 1.37 and 1.96 V, and a reversible two-electron reduction between -0.05 and -0.23 V. The solution UV-vis-NIR spectrum of each compound is dominated by an intense (ε ? 100 000 M-1 cm-1) low energy π-π* transition that has a γmax ranging between 648 and 790 nm. All X-ray crystal structures exhibit very planar quinoidal backbones and short intermolecular π-stacking distances (3.335-3.492 A). Structures exhibit a single π-stacking distance with parallel cofacial stacking (sulfur atoms of equivalent rings pointed in the same direction) or with alternating distances and antiparallel cofacial stacking (sulfur atoms of equivalent rings pointed in the opposite direction). Examples of the layered and herringbone-packing motifs are observed for both the parallel and the antiparallel cofacial stacking. Analysis of the X-ray structures and molecular orbital calculations indicates that all of these compounds have one-dimensional electronic band structures as a result of the π-stacking. For structures with a unique π-stacking distance, a simple geometric overlap parameter calculated from the shape of the molecule and the slip from perfect registry in the π-stack correlates well with the transfer integrals (f) calculated using molecular orbital theory. The calculated valence (633 meV) and conduction (834 meV) bandwidths for a quinoid quaterthiophene structure are similar to those calculated for the benchmark pentacene and indicate that both hole and electron mobilities could be significant.
