A New BDT-Based Conjugated Polymer with Donor-Donor Composition for Bulk Heterojunction Solar Cells

Abstract

We present the synthesis and photovoltaic application of a conjugated polymer, PBDT-KTBDT, composed of two benzo[1,2-b:4,5-b']dithiophene (BDT)-based units. In detail, PBDT-KTBDT is composed of alkoxy-substitued BDT units as the electron donating groups and alkylcarbonythienyl-substitued BDT units as the electron withdrawing moieties. The proposed polymer exhibits good solubility, sufficient thermal stability, moderate UV-vis absorption wavelength and energy levels. Solution-processed organic solar cells were fabricated using PBDT-KTBDT as an electron donor and PC71BM as an electron acceptor, and a power conversion efficiency of 1.50% was obtained. Our results reveal that the copolymer with donor-donor composition is a viable candidate as a semiconductor in OPVs, and it is possible to further improve solar cells through more extensive research on these two BDT units-based materials.