Design and synthesis of triphenylamine-substituted vinyl sulphide and its derivatives for fully transparent-to-black electrochromism

Herein, we report the design and green synthesis of stereodefined tetrasubstituted alkenes (TPA-V-S, TPA-V-SO, and TPA-V-SO2) bearing a triphenyl amine (TPA) and a sulfenyl or sulfoxide, or sulfone functional group situated in the anti-orientation and two phenyl rings anti to each other. Notably, TPA-V-S exhibited reversible vis-to-NIR electrochromism with a high optical contrast of 70.6%, suitable for transparent-to-black (TTB) smart window applications. Additionally, the electrochromic smart window effectively decreased the solar heat gain by 82% in the black state.