Doping a D-A structural polymer based on benzodithiophene and triazoloquinoxaline for efficiency improvement of ternary solar cells

A novel donor-acceptor (D-A) structural polymer PBDT-BTzQx-C12 consisting of benzodithiophene and triazoloquinoxaline units as donor and acceptor building blocks was synthesized. The PBDT-BTzQx-C12 was evaluated as complementary electron donor in polymer solar cells (PSCs) with poly(3-hexylthiophene) (P3HT) as electron donor and [6,6]-phenyl-C71-butyric acid methyl ester (PC71BM) as electron acceptor. The power conversion efficiencies (PCEs) of PSCs were improved from 3.18% to 3.54% by doping 2 wt. % PBDT-BTzQx-C12, corresponding to an approximately 11% PCE improvement. The performance improvement of ternary PSCs should be attributed to the increase of photon harvesting and the optimized phase separation of active layers by doping D-A structural PBDT-BTzQx-C12.