Unaxisymmetric Non-Fused Electron Acceptors for Efficient Polymer Solar Cells

To develop photovoltaics embracing the both features of high performance and low cost has drawn attentions of researchers,yet representing the significant challenges.In this work,two non-fused ring acceptors(NFRAs),namely p-PTIC4Cl and t-PTIC4Cl,were developed via a short synthetic route.By tethering unaxisymmetric aromatic chains to thienyl bridge of NFRAs,we revealed that the tuning of aromatic chains allows modulating the self-assembly and stacking of NFRAs in solid,hence influencing their optoelectronic and photovoltaic properties.As results,p-PTIC4Cl,consisting of 3-hexylbenzene with large axial angle to backbone,can achieve superior PCE of 11.30%than that of t-PTIC4Cl with 2-hexylthiophene chains(PCE of 6.49%),when pairing with polymer donor PBDB-TF.Despite of the only subtle structural difference,the p-PTIC4Cl based blend films possess better exciton dissociation and charge transfer rates,as well as photostability,to those of t-PTIC4Cl based blends.