A new two-dimensional tetrathienyl-TBDT (TBDT-4T) was synthesized by employing palladium-catalyzed C─H benzannulation between an iodobiaryl and 1,2-dithienylacetylene. The stannylated TBDT-4T was copolymerized with di(thiophenyl)difluorobenzothiadiazole (FBT) and fluorothienothiophene (FTT) monomers to yield PTBDT-FBT and PTBDT-FTT, which showed high decomposition temperatures (421 and 408°C) and deep-lying HOMO levels (−5.80 and −5.84 eV). The inverted solar cell device using PTBDT-FBT:PC71BM (1:1 in wt%) blend showed a power conversion efficiency (PCE) of 4.16%, while the device using PTBDT-FTT:PC71BM (1:2 in wt%) blend showed a PCE of 3.98%.
- Ladder-type polymer
- Palladium-catalyzed C─H arylation
- Polymer solar cell
- Two-dimensional structure