NOVELTY - Synthesis of 3,4,5-trimethoxythiophenol derivative (I) includes carrying out decarboxylation nitration of 3,4,5-trimethoxybenzoic acid under concentrated nitric acid and acetic acid; reacting aromatic amine (II) with sodium nitrite and hydrochloric acid solution and reacting with sodium iodide; dissolving 3,4,5-trimethoxyphenyl ethyl xanthate in tetrahydrofuran and reducing with lithium aluminum; and dissolving 3,4,5-trimethoxythiophenol and aromatic iodide (III) in ethylene glycol and isopropanol or toluene and reacting with potassium carbonate and cuprous iodide.    USE - Method for synthesizing 3,4,5-trimethoxythiophenol derivative (claimed) used as electron transport layer of solar cell.    DETAILED DESCRIPTION - Synthesis of 3,4,5-trimethoxythiophenol derivative of formula (I) comprises:    (A) carrying out decarboxylation nitration of 3,4,5-trimethoxybenzoic acid under concentrated nitric acid and acetic acid to obtain 3,4,5-trimethoxynitrobenzene;    (B) reducing obtained product with zinc powder/acetic acid or palladium on carbon/hydrazine hydrate to obtain 3,4,5-trimethoxyaniline;    (C) reacting obtained product with sodium nitrite and hydrochloric acid to obtain diazonium salt solution and reacting with potassium ethyl xanthate to obtain 3,4,5-trimethoxyphenyl ethyl xanthate;    (D) reacting aromatic amine of formula (II) with sodium nitrite and hydrochloric acid solution to obtain diazonium salt and reacting with sodium iodide to obtain aromatic iodide of formula (III);    (E) dissolving 3,4,5-trimethoxyphenyl ethyl xanthate in tetrahydrofuran and reducing with lithium aluminum to obtain 3,4,5-trimethoxythiophenol; and    (F) dissolving 3,4,5-trimethoxythiophenol and compound (III) in ethylene glycol and isopropanol or toluene and reacting with potassium carbonate and cuprous iodide.    A=groups of formulae (i)-(iv);    R 1-R 8,R 10-R 18=H, halo, OH, NH 2, substituted-NH 2, -CN, 1-6C alkyl, 1-6C alkoxy, -NO 2, amide, acyl, aldehyde, carboxy, 1-6C alkoxycarbonyl, acyloxy alkoxy, or F, Cl, or Br substituted alkyl;    R 9=1-3C alkyl or 1-3C substituted alkyl; and    X,Z=N, O, or S.