Synthesis and optical properties of photovoltaic materials based on the indenofluorines and ambipolar dithienonaphthothiadiazol

Dithieno[3´2´:5,6;2",3":7,8]naphtho[2,3-c][1,2,5] thiadiazole (DTNT) and Indeno[2,1-c]fluorine (IF) derivatives were designed to control the band energies of the photovoltaic materials. Electrochemical analysis showed that DTNT acts as both an electron donor and an electron acceptor, revealing the ambipolar nature of the DTNT unit. The direct arylation polymerization of DTNT with 2,2´-bithiophene (BTh) and 3,6-bis(2-thienyl)pyrrolo[3,4-c]pyrrole-1,4-dione (DPP) afforded four polymers, and the PDTNT-DPP exhibited narrow band gap energy of 1.4 eV and a low HOMO energy of -5.43 eV. The IF derivatives with low HOMO and LUMO energies were designed and synthesized as an electron accepter for the PDTNT-DPP.