Poly(alkyl thiophene-3-carboxylates). Synthesis and Characterization of Polythiophenes with a Carbonyl Group Directly Attached to the Ring

Abstract

Polythiophenes with electron-withdrawing ester groups attached at the 3-position, namely poly(hexyl thiophene-3-carboxylate) (la) and poly(octyl thiophene-3-carboxylate) (lb), have been synthesized using the Ullmann reaction with copper powder in DMF. Characterization of the polymers includes IR, and 13C NMR, and UV-vis spectroscopy as well as TGA and molecular weight studies. The polymers also show red-orange and red fluorescence, respectively. The same polymers prepared using Ni(0) instead of Cu gave polymer with comparable molecular weights but higher polydispersity, which was not as uniform as shown by NMR spectroscopy and which had shorter conjugation lengths, as shown by blue-shifted UV-vis absorption and fluorescence maxima.

Light‐Emitting Polythiophenes

“…[37] Both polymers had similar molecular weights (number-average molecular weights (M n ) of 3000 g mol ±1 ), although the Cu-prepared polymers showed less defects and lower polydispersity indexes. PL emission maxima for the Cu-prepared polymers 11a,b were red-shifted compared to the Ni-prepared polymers (by 13±15 nm (» 0.05±0.06 eV) in solution and 25± 30 nm (» 0.08±0.10 eV) in films, see Table 1).…”

“…Pomerantz et al prepared regioregular polymers HHTT11a,b and compared them with previously synthesized [37] irregular polymers 11a,b. Regioregular polymers showed blueshifts in absorption for solution and films (23±30 nm and 57±79 nm, respectively; Table 1), interpreted in terms of shorter conjugation lengths.…”

“…Averaging over the EL, PL, and absorbance data, the effective conjugation length was estimated as approximately 9±10 thiophene units. End-capping of terthiophene and quaterthiophene with triphenylamino groups (37), which led to stable amorphous glasses, can afford relatively high luminescence efficiencies of 0.03 and 1.1 lm W…”

The Chemistry of Conducting Polythiophenes

“…The conductivities of FeCl 3 -doped materials were in the 0.1±0.0001 S/cm range. Ullmann coupling polymerization of 2,5-dibromo-3-alkylthiophene carboxylates as described by Pomerantz et al is an excellent way to prepare ester derivatives of PTs [181] (Scheme 16). The molecular weight M n of these materials was in the 4k region with PDIs around 2.…”

Thermal behaviour of dicarboxylic ester bithiophene polymers exhibiting a high open-circuit voltage

“…44,45 However, the oxidation potential of polythiophenes can be increased by using electron-withdrawing ester side chains. 46 As a result, the V oc can be increased. 47 Significant progress was made by the introduction of dicarboxylic bithiophene polymers (PDCBT), which exhibit a high V oc of 0.91 V and a PCE up to 7.2%, 48 in combination with [6,6]-phenyl-C 71 -butylric acid methyl ester (PC 71 BM).…”