structures and optical properties of tris(trimethylsilyl)silylated oligothiophenes were examined by spectroscopies, theoretical calculations, and single-crystal X-ray measurements. Bathochromic shift from the original oligothiophenes was observed in the tris(trimethylsilyl)silylated ones, confirming the σ–π conjugation between Si–Si σ bonds and π-orbital. 5,5′-Bis(tris(trimethylsilyl)silyl)-2,2′-bithiophene