All-in-one Dual-Band Electrochromic Devices Based on Viologen Derivative

A viologen derivative, 1- (4- (trifluoromethyl) benzyl) -4- (4- (1- (4-vinylbenzyl) pyridin-1-ium-4-yl) phenyl) pyridin-1-ium (FBPCV), with modulation properties in the Visible/near-infrared dual-band was prepared, and further cross-linking and polymerization with poly (ethylene glycol) diacrylate to produce electrochromic device (ECD) in the gel state. The trifluoromethyl group is introduced to increase the π-conjugation of the viologen to enhance its spectra modulation range and to avoid dimerization of the viologen by using the repulsion of the fluorine atoms. The maximum transmittance modulation of FBPCV-ECD in the visible/near-infrared dual-band reaches 74.25 % and 67.15 %, respectively, and its good stability enables it to maintain the initial transmittance modulation range of 91.3 % after 5000 cycles, which is a good prospect for the application of electrochromic smart windows.