The study of the electrochemical fluorescence switching properties of the conjugated copolymers containing fluorene, triphenylamine, and 1,3-diphenylimidazolidin-2-one moieties is reported. The polymers show high fluorescence quantum yields, excellent thermal stability, and good solubility in polar organic solvents. While the polymer emits blue light under UV irradiation, the fluorescence intensity is quenched upon electrochemical oxidation. The fluorescent behavior can be reversibly switched between nonfluorescent (oxidized) state and strong fluorescence (neutral) state with a high contrast ratio (If/If0) of 16.3. The role of the electrochemical oxidation of the triphenylamine moieties is to generate the corresponding radical cations that lead to fluorescence quenching in the solid matrix. (C) 2012 Wiley Periodicals, Inc. J. Polym. Sci. Part A: Polym Chem, 2012