New alkylthio-thieno[3,2-b]thiophene-substituted benzodithiophene-based highly efficient photovoltaic polymer

We introduced an alkylthio-substituent on the thieno[3,2-b]thiophene side chain of the polymer and synthesized a new low band gap 2D-conjugated polymer, PSTTBDT-FTT. It showed more red-shifted absorption spectra and higher hole mobility than PTTBDT-FTT without the thio-functionality. The power conversion efficiency (PCE) of the PSTTBDT-FTT device reached 8.61%. This work demonstrates that the newly synthesized PSTTBDT-FTT is a promising donor material for high efficiency OPVs.