Synthesis and electrochromic properties of a carbazole and diketopyrrolopyrrole-based small molecule semiconductor

[Display omitted] Carbazoles are excellent chromophores for electrochromic (EC) applications owing to their exceptional oxidation properties. Herein, we synthesized a donor-acceptor-type small molecule semiconductor, named LGC-D023, containing carbazole as a core donor, diketopyrrolopyrrole as a weak-acceptor π-linker, and 3-octylrhodanine as an electron-acceptor end-unit; and characterized its optical, thermal, and EC properties. LGC-D023 exhibited good organic solvent solubility, as well as distinct melting and crystallization transitions above 200°C. Spectroelectrochemical spectra showed blue (L*: 88.28, a*: −6.56, b*: −1.29)-to-red (L*: 93.61, a*: 2.94, b*: −0.75) color switching with a high optical contrast (35.3%), fast response time (>0.3s), and desirable coloration efficiency (91.9 cm2/C). These results confirmed that this donor-acceptor small molecule could be a new promising candidate for an EC material.