Highly soluble diketopyrrolopyrrole-based donor-acceptor type small molecule for electrochromic applications

Despite the great potential presented by small molecular compounds, small molecule electrochromic materials receive less attention than polymer-based electrochromic materials. In this work, the synthesis of a novel π-conjugated small molecular electrochromic material, LGC-D055, is described. This material contains dithiophene-phenylene with a bulky trihexylsilyloxy side chain at its core, diketopyrrolopyrrole with a siloxane-terminated hybrid alkyl chain as the linker, and ethylrhodanine as the end group. LGC-D055 presents excellent solubility in organic solvents due to the presence of these bulky side chains. The spin-coated films of LGC-D055 exhibit blue/transparent electrochromism with a fast switching speed of 0.4 s and high coloration efficiency over 300 cm2/C.