An A-D-D-A-type small-molecule electron acceptor with chlorine substitution for high-efficiency polymer solar cells

Chlorination is a very effective technique to adjust molecular energy levels, absorption spectra and intermolecular pi-pi stacking of small-molecule acceptors (SMAs). On this basis, a new acceptor-donor-donor-acceptor (A-D-D-A)-type SMA IDT2-IC-4Cl with chlorinated end units was developed. Compared with the unchlorinated counterpart (IDT2-IC), the IDT2-IC-4Cl exhibited an efficient absorption ability in the range of 550-900 nm region. Moreover, the blend films of PBDB-T:IDT2-IC-4Cl exhibited better charge generation properties and more balanced charge mobilities as compared to those of PBDB-T:IDT2-IC blend films. Polymer solar cells (PSCs) based on PBDB-T:IDT2-IC-4Cl exhibited a power conversion efficiency (PCE) of 12.53% with a short-circuit current (J(SC)) of 22.22 mA cm(-2) and a fill factor (FF) of 69.81, while the PBDB-T:IDT2-IC device yielded a PCE of 8.18% with a J(SC) of 13.23 mA cm(-2) and a FF of 65.71. The results show that chlorination is an effective way to obtain high-performance SMAs.

Automated summary

Chlorination is an effective technique to adjust the performance of SMAs, with chlorinated end units enhancing the absorption ability and improving the performance of polymer solar cells. Chlorination proves to be an effective approach in obtaining high-performance SMAs.