The invention provides an electrochromic
copolymer containing dioxythiophene and a 9, 9 '-spirobifluorene structure, the molecular formula of the electrochromic
copolymer comprises the following structure: A represents
sulfur or
oxygen, and m and n both represent the
degree of polymerization and are integers between 8 and 100. The preparation method comprises the following steps: (1) adding 3, 4-dioxo-1, 3, 4-thiadiazole and The preparation method comprises the following steps: adding 2, 2 ', 7, 7'-tetrabromo-9, 9 '-spirobifluorene, 3, 4-dibromo
ethylene dioxythiophene or 3, 4-dibromo
ethylene dithio
thiophene, N, N-
dimethylacetamide,
potassium carbonate,
palladium acetate and
pivalic acid into a single-mouth flask, carrying out air suction and exchange on the single-mouth flask by using
nitrogen or
argon, keeping an
air exchange atmosphere, sequentially heating and reacting the mixture, cooling to
room temperature, dropwise adding into
methanol, and carrying out a reaction under the protection of
nitrogen or
argon so as to obtain a target product, namely the 2, 2', 7, 7 '-tetrabromo-9, 9'-spirobifluorene. Filtering and collecting orange red precipitates; and 2) placing the orange red precipitate in a fat extractor, sequentially dissolving and washing with
methanol, n-
hexane and
chloroform, concentrating a
chloroform washing solution, finally dropwise adding into
methanol, filtering and collecting the precipitate, thereby obtaining the target product.