Rational Materials Design And Device Application Of Ternary Conjugated Polymers

Narrow band gap D-A conjugated polymer P1 and D1-A-D2-A ternary conjugated polymer P2 with regioregular backbone structure were designed and synthesized.By precisely controlling the arrangement of the third building block,the polymer properties can be comprehensively and delicately tuned,resulting in more balanced optical bandgap and highest occupied molecular orbital(HOMO)energy levels,planar structure and strong intermolecular packing.Here,the influence of third unit on material microcosmic and macrocosmic properties was examined exclusively.By using [70]PCBM as the electron acceptor,the optimized polymer solar cells without any additive demonstrated an increased open circuit voltage(Voc),short-circuit current density(Jsc)and fill factor(FF)in ternary polymer P2 based device,and a best PCE of 5%,which is significantly enhanced in comparison with D-A polymer P1 based device.Our results highlight the importance of ternary molecular designing strategy and may achieve control of desirable device properties by optimizing molecular structure in the future.