We designed and synthesized two donor-pi-acceptor-type dithieno[3,4-b:3',4'-d]phosphole derivatives. The position of substituents on the dithienophosphole moiety was found to play an important role in the frontier molecular orbitals and the hybrid character of electron-withdrawing phosphole and electron-donating thiophene. Thus, the modulation of frontier molecular orbitals would be an effective strategy to develop organic functional materials based on dithieno[3,4-b:3',4'-d]phospholes.