Dual Cathodically and Anodically Coloring Electrochromic Polymer Based on a Spiro Bipropylenedioxythiophene [(Poly(spiroBiProDOT)]

Three color states and a large luminance change at intermediate potentials are the key features of a new alkylenedioxypolythiophene, in which two polymeric strands are linked by a spiro(bis-dioxacycloheptene) unit (see Figure). The seven-membered rings are quite flexible and allow coplanarity of both strands. The polymer is both cathodically and anodically coloring, showing a dark red neutral state and a dark blue oxidized state.