Enhanced photovoltaic performances of bis(pyrrolo[3,4-c]pyrrole-1,3-dione)-based wide band gap polymer via the incorporation of an appropriate spacer unit between pyrrolo[3,4-c]pyrrole-1,3-dione units

Bis(pyrrolo[3,4-c]pyrrole-1,3(2H,5H)-dione) (BDPPD)-based new electron deficient monomer unit (TTBDPPD) incorporating thieno[3,2-b]thiophene as a connecting spacer unit in between pyrrolo[3,4-c] pyrrole-1,3(2H,5H)-dione units was prepared. The copolymerization of 2D-conjugated benzodithiophene (BDTT) and TTBDPPD derivatives afforded new alternating copolymer P(BDIT-TTBDPPD). The estimated optical band gap and highest occupied molecular orbital (HOMO)/lowest unoccupied molecular orbital (LUMO) energy levels of P(BDTT-TTBDPPD) were 2.06 eV and -5.42 eV/-336 eV, respectively. The organic field effect transistor made form P(BD1T-TTBDPPD) exhibited a hole mobility of 6.21 x 10(-4) cm(2)V(-1)s(-1). The polymer solar cells (PSCs) prepared using P(BD1T-TTBDPPD):PC70BM (1:2 wt %)+3 vol% DIO blend offered a maximum power conversion efficiency (PCE) of 537% with an open-circuit voltage (V-oc) of 0.90 V, a short-circuit current (J(sc)) of 8.94 mA/cm(2) and a fill factor (FF) of 67%. This study reveals that the photovoltaic performance of BDPPD-based reported polymer, P(BDIT-TBDPPD), incorporating thiophene spacer unit in between pyrrolo[3,4-c]pyrrole-1,3(2H,5H)-dione units has been greatly improved (over 2%) when thiophene replaced with thieno[3,2-b]thiophene. (C) 2016 Elsevier B.V. All rights reserved.