2,5-bis-(2-butyl-octyl)-3,6-bis- [5-(4-carbazol-9-yl-phenyl)-thiophen-2-yl]-2,5-dihydro-pyrrolo[3,4-c]pyrrole-1,4-dione (PCTDPP12) based on carbazole and diketopyrrollopyrrole is synthesized by the Suzuki couplingreaction. The optical and electrochemical properties of PCTDPP12 are investigated by a UV-visiblespectrophotomerty and a cyclic voltammerty. The maximum absorption wavelength of PCTDPP12 solution andfilm are appeared at 643 nm, 671 nm and the optical band gap of PCTDPP12 was 1.84 eV. The maximumabsorbance and wavelength of the film are dramatically changed upon heat treatment. The HOMO and LUMOenergy level of PCTDPP12 estimated from the cyclic voltammetry are–5.34 eV and –3.54 eV, respectively.