Synthesis of a conjugated pyrrolopyridazinedione–benzodithiophene (PPD–BDT) copolymer and its application in organic and hybrid solar cells

ABSTRACT: Herein, we describe the synthesis and characterization of a conjugated donor–acceptor copolymer consisting of a pyrrolopyridazinedione (PPD) acceptor unit, and a benzodithiophene (BDT) donor unit. The polymerization was done via a Stille cross-coupling polycondensation. The resulting PPD–BDT copolymer revealed an optical bandgap of 1.8 eV and good processability from chlorobenzene solutions. In an organic solar cell in combination with PC(70)BM, the polymer led to a power conversion efficiency of 4.5%. Moreover, the performance of the copolymer was evaluated in polymer/nanocrystal hybrid solar cells using non-toxic CuInS(2) nanocrystals as inorganic phase, which were prepared from precursors directly in the polymer matrix without using additional capping ligands. The PPD–BDT/CuInS(2) hybrid solar cells showed comparably high photovoltages and a power conversion efficiency of 2.2%. GRAPHICAL ABSTRACT: [Image: see text]