基于氟化侧链的二(噻吩并环戊二烯)并咔唑非富勒烯受体材料合成及光伏性能OA

Side-chain fluorination of non-fullerene acceptors(NFAs)has rarely been reported to enhance the per-formance of organic solar cells,despite its critical role in boosting the carrier mobility property.Three acceptor-do-nor-acceptor(A-D-A)type acceptors(HP1,HP2,and HP3)based on dithienocyclopentacarbazole are successfully designed and synthesized.The effects of fluorinations in side-chains and ending groups on the final photovoltaic per-formance are investigated in detail.Compared to HP2 with fluorinated side-chains,HP1 with fluorinated ending groups shows red-shifted absorption and down-shifted energy levels.For HP3 with fluorination in both side-chains and ending groups,the lowest unoccupied molecular orbital(LUMO)energy level is up-shifted to-3.88 eV in spite of its slightly enlarged optical bandgap in comparison with that of HP1.The PM6∶HP3 blend presents better morphol-ogy and carrier transport property than HP1-and HP2-based counterparts,and thereby leading to an increased power conversion efficiency(PCE)of 11.48％with an open-circuit voltage(Voc)of 0.97 V for the corresponding device.However,the HP1-based device delivers a decreased PCE of 11.08％with a reduced Voc of 0.93 V.And,the PCE based on PM6∶HP2 blend is only 4.20％.It should be noted that the organic solar cells based on PM6∶HP1∶HP3(1∶0.5∶0.5,w/w/w)affords an enhanced PCE of 11.95％.The findings indicate that rational fluorinated side-chain engineering can significantly enhance the photovoltaic performance of NFAs.