Theoretical Investigations on Naphthodithiophene Diimide‐Based Copolymers as Acceptor for All‐Polymer Solar Cell Applications

Abstract

AbstractWe present an effective approach to modulate the electron‐withdrawing ability and the molecular planarity in donor‐acceptor (D−A) copolymer in order to develop the design strategy of acceptor polymers for improvement of the organic solar cell (OSC) performances. To confirm this strategy, based on a series of the D−A polymers (PNDIT (P1), PNDIS (P2) and PNDIBz (P3)), by modification of the electron‐withdrawing capability on those polymer backbones, a series of new D−A polymers (Pa1‐Pa3) were designed. The polymers Pa1‐Pa3 exhibit better planarity than that of corresponding P1‐P3, respectively. Compared with the properties of P1‐P3, Pa1‐Pa3 as acceptor materials not only yield a redshift and stronger absorption spectrum which results in a wider absorption within the solar spectrum, but also show much better electron acceptor properties, smaller exciton binding energy for charge dissociation and larger electron mobility. The results confirmed that the design strategy on adjustment of the electron‐withdrawing ability and the molecular planarity in D−A copolymer is a reliable approach to obtain the promising polymers as acceptors in OSC applications.