2-Methylthio- and 2-n-hexylthienyl-6-(tricyanoethenyl)-4,4-diphenyldithienosilole were prepared as novel push-pull type compounds. These compounds exhibit solvatochromic behaviors with respect to their UV-vis absorption and emission spectra. Clear vapor chromism is also observed for their thin solid films and the color changed clearly on exposure of the films to organic solvent vapors, indicating the potential applications to VOC sensors.