Thieno[3,2-b]thiophene-2-carbonitrile, also known as 2-Cyanothieno[3,2-b]thiophene, belongs to the family of fused thiopehenes which are electron-rich and?structurally rigid?with extended π-conjugation. They are good candidates for adjusting the band gap of organic polymer semiconducting materials.?Thieno[3,2-b]thiophene-2-carbonitrile is used as an intermediate for the synthesis of small molecules and polymers in the application of organic field-effect transistors (OFETs), and as organic photovoltaic devices (OPV) interface layers as HTL or ETL materials.