Direct Arylation Polycondensation of Chlorinated Thiophene Derivatives to High-Mobility Conjugated Polymers

Abstract

High-mobility conjugated polymers (CPs) that can be synthesized in a large scale by direct arylation polycondensation (DArP) are highly desired for printable electronics. To realize this purpose, a readily accessible C–H monomer with high reactivity and selectivity is crucial. Herein, we demonstrated that chlorination enables the efficient DArP of thiophene derivatives, i.e., 3,3′,4,4′-tetrachloro-2,2′-bithiophene (4ClBT) and (E)-1,2-bis­(3,4-dichlorothien-2-yl)­ethene (4ClTVT), which can be prepared with no more than two steps. No evidence of structure defects was found in the resulting polymers. This finding allows the facile synthesis of high-molecular-weight CPs via DArP. The presence of Cl···S weak intramolecular interaction, which can improve the coplanarity of conjugated skeleton, was confirmed by single-crystal structural analysis. With diketopyrrolopyrrole derivatives as C–Br monomers, CPs with electron mobility up to 1.44 cm2 V–1 s–1 in air have been obtained via DArP. This work demonstrates that chlorinated thiophene derivatives are promising C–H monomers for large-scale synthesis of high-mobility CPs via an atom-economical and “green” method, i.e., DArP.

Diketopyrrolopyrrole-based conjugated polymers synthesized by direct arylation polycondensation for anisole-processed high mobility organic thin-film transistors

“…Both polymers show similar absorption features with two absorption bands, which is common to DPP-based CPs. 42,43,58,61,64 Solvent effect on the absorption spectra in both solution and film states is rather small. As shown in Table 1, the low energy absorption maxima ( λ max s) of Fu-F in three solvents are slightly different, which are at 797, 790 and 792 nm in anisole, o -xylene and o -DCB, respectively.…”

“…4FTVT, 4ClTVT and 3,6-bis(5-bromofuran-2-yl)-2,5-bis(4-tetradecyloctadecyl)-pyrrolo[3,4- c ]pyrrole-1,4(2 H ,5 H )-dione (FDPP-Br) were prepared according to previous studies. 43,58,61 DArP was conducted following our previously reported procedure by using toluene as the solvent. 58,61 The resulting Fu-F and Fu-Cl were purified by precipitation in methanol and Soxhlet extraction with ethanol, acetone and hexane in succession.…”

“…43,58,61 DArP was conducted following our previously reported procedure by using toluene as the solvent. 58,61 The resulting Fu-F and Fu-Cl were purified by precipitation in methanol and Soxhlet extraction with ethanol, acetone and hexane in succession. The molecular weights of the polymers were determined by high-temperature gel permeation chromatography (HT-GPC) at 150 °C using 1,2,4-trichlorobenzene (TCB) as the eluent and polystyrene (PS) as the standard.…”

“…In contrast, analogous polymers based on thiophene-flanked DPP (TDPP), i.e. , Th-F and Th-Cl , 61,64 are almost insoluble in anisole (Table S1, ESI†). This observation is consistent with our previous study on poly(diketopyrrolopyrrole- alt -terchalcogenophene)s: introducing furan units at 3,6-positions of DPP can dramatically improve the solubilities of the DPP-based CPs.…”

“…, ( E )-1,2-bis(3,4-difluorothien-2-yl)ethene (4FTVT) 58–60 and ( E )-1,2-bis(3,4-dichlorothien-2-yl)ethene (4ClTVT). 61 Two CPs, named Fu-F and Fu-Cl , that are soluble in o -xylene and anisole were successfully synthesized (Scheme 1). Top-gate/bottom-contact (TGBC) OTFTs with a reliable electron mobility ( μ e ) of up to 2.79 cm 2 V −1 s −1 have been fabricated with anisole as the solvent.…”