Two fused cyclopentadithiophenebis(dicyanovinylene) derivatives (FCPDT-16 and FCPDT-C24) with a low-lying LUMO energy level (3.88 eV) and a rigid core structurewere successfully synthesized.They have good thermal stability and form highly ordered packing structures both in the bulk solid state and in thin films. The field effect transistors fabricated from a solution of these two compounds showed ambipolar behaviour with major n-channel operation. FCPDT-C16 exhibited electron mobility up to 0.16 cm(2) V(-1) s(-1).