New π-conjugated polymers as acceptors designed for all polymer solar cells based on imide/amide-derivatives

Abstract

In this paper we report two n-type polymeric acceptors P1 and P2 based on imide/amide-derivatives (PDI, NDI and DPP). P1 and P2 exhibit very different optical properties which may be related to the different molecular configuration and polymeric crystallinity. All polymer solar cells were fabricated with conventional configuration based on polymeric donor PBDTTT-C-T and P1/P2. Results reveal that devices based on P1 show the best performance with a PCE of 2.01%, a V_OC of 0.68 V, a J_SC of 7.06 mA cm⁻² and a FF of 41.78%, which is attributed to the appropriate energy levels, relatively high electron mobility and preferable micro-phase separation. The poor performance for P2 (PCE = 0.30%) was mainly ascribed to its extremely low J_SC which was probably caused by the small HOMO energy level difference between donor and P2.