Synthesis, ¹H and ¹³C NMR assignment and electrochemical properties of novel thiophene–thiazolothiazole oligomers and polymers

Abstract

Novel hexyl-substituted bisthiophene compounds containing a thiazolothiazole(5,4-d) unit have been explored. The molecules are soluble in common organic solvents, which would enhance their chance of possible integration in printable electronics. Synthesis and complete elucidation of the chemical structures by detailed 1D/2D NMR spectroscopy are described. This provides interesting input for chemical shift prediction software, because few experimental data on this type of compounds are available. Furthermore, the potential n-type character of these derivatives is verified using electrochemical measurements. In addition, the low-bandgap character of conjugated polymers containing the thiazolothiazole unit is demonstrated by performing an electropolymerization.

Charge transfer in the weak driving force limit in blends of MDMO-PPV and dithienylthiazolo[5,4-d]thiazoles towards organic photovoltaics with high VOC

“…1 and Table 1), which were also underpinned by density functional theory calculations of the electronic properties. 9,10 The CT to a reference donor polymer demonstrated for 4-CN-Ph-DTTzTz, in combination with the high charge mobility expected in this type of thiophene-based derivatives, is promising for the application of related DTTzTz materials as acceptors in D-A blends for 3D BHJ solar cells.…”

“…Complementary information on the HOMO and LUMO energy levels and the resulting bandgaps as derived for the 4 compounds from cyclic voltammetry (CV) in CH 3 CN solution is also listed. 9,10 Among the workhorse donor polymers for BHJ solar cells, MDMO-PPV was chosen as a partner to the DTTzTz molecules because of the high LUMO level increasing the chances for efficient CT. The tendency for crystallization in the pure DTTzTz spin-coated films resulted in long-wavelength tails due to diffuse scattering.…”

Combined experimental–theoretical NMR study on 2,5‐bis(5‐aryl‐3‐hexylthiophen‐2‐yl)‐thiazolo[5,4‐d]thiazole derivatives for printable electronics

“…The common precursor for the reported TzTz semiconductors, 2,5‐bis(3‐hexylthiophen‐2‐yl)thiazolo[5,4‐ d ]thiazole ( P1 ), was synthesized in moderate yield (47%) via a condensation reaction at elevated temperature (200 °C) between dithiooxamide and an excess of 3‐hexylthiophene‐2‐carbaldehyde, prepared according to a modified literature procedure (Scheme ) . The resulting product mixture required extensive purification (column chromatography and two successive recrystallizations from ethanol and acetonitrile) to convert the black crude residue into pure yellow crystals of P1 .…”

“…After subsequent dibromination with N ‐bromosuccinimide (71% yield), the final TzTz derivatives D1 , D2 , D3 , and D4 were obtained through Suzuki cross‐coupling reactions with the respective boronic acids or esters (Scheme ) . The dithienyl‐substituted TzTz counterpart D0 has previously been prepared by an analogous Stille protocol . The cross‐coupling reactions were in general very effective, main product losses occurring during the tedious material purification (by repetitive recrystallization and column chromatography), affording highly pure materials for device applications.…”

“…Table presents an overview of all signal assignments for D0–D4 . The complete NMR analysis of TzTz D0 has previously been reported . Such a detailed analysis is useful because the obtained chemical shift information can be helpful in further research on TzTz moieties, for instance by implementation in NMR‐based prediction software.…”