New alternating electron donor–acceptor conjugated polymers entailing (E)-[4,4′-biimidazolylidene]-5,5′(1H,1′H)-dione moieties

Abstract

Four new alternating D–A polymers (P1–P4) with (E)-[4,4′-biimidazolylidene]-5,5′(1H,1′H)-dione (BID) as electron accepting moieties were synthesized and characterized. Based on GPC (gel permeation chromatography) data, M_ws of P1–P4 are relatively high ranging from 11.8 to 14.7 kg mol⁻¹ with polydispersities of 1.8–1.9. Thin-films of P1–P4 show broad and strong absorptions up to 950 nm. HOMO (−5.11 eV to −5.32 eV) and LUMO (−3.71 eV to −3.81 eV) energies as well as band gaps (1.40 eV to 1.53 eV) were determined based on their onset redox potentials and absorption spectra. Field-effect transistors with thin-films of P1–P4 were successfully fabricated with conventional techniques. The results reveal that thin-films of P1 and P2 exhibit relatively high hole mobilities of up to 6.6 × 10⁻³ cm² V⁻¹ s⁻¹.