Perylene diimide (PDI) and their derivatives have received a great deal of interest in developing novel polymer acceptors as one of the most promising electron accepting materials in all-polymer solar cells (all-PSCs) because of their outstanding chemical and physical properties, such as cheap cost, high molar absorption efficiency, good electron mobilities and easily functionalization. Extensive research efforts have been devoted to the new design and modification of the PDI-based polymers as the n-type polymeric acceptors. With the advancement of p-type polymer donor and morphological optimization, the device performances with PDI-based polymeric acceptor have gradually been improved. Considering the availabilities of PDI polymers, further exploration of the new PDI-based polymeric acceptors with the above-mentioned benefits will be able to provide the promising opportunities to increase the performances of all-PSCs.
In this meeting, we will report our works on the novel fused PDI-based polymers as the electron acceptor in all-PSCs. The fused PDI polymers contain the fusion of two PDI units through the bay region, and we find that this kind of design strategy is highly effective to enhance the photovoltaic performances of all-PSCs. We have copolymerize the fused PDI unit with thiophene, bithiophene, thieno[3,2-b]thiophene, selenophene, benzo[1,2-c;3,4-c']dithiophene and indacenodithiophene, etc to make more than ten polymers, and investigated their applications in all-PSCs. We also find that the combinations of the PDI unit and the comonomers also have significant effect on the optical, electrochemical, morphological and photovoltaic properties. With the optimization of the molecular structure of fused PDI unit, the all-polymer solar cells based on these fused PDI polymer acceptors could achieve the power conversion efficiency of more than 7%, which is much higher than its non-fused PDI counterparts. Our results demonstrate a general design rule for further improving the photovoltaic performances of the PDI-based polymer acceptors.