基于二噻吩并吡咯π桥的窄带隙非富勒烯受体材料在有机太阳能电池中的应用

以不同烷基取代的二噻吩并吡咯(DTP)为π桥,连接吲哒省并二噻吩(IDT)中间单元和氰基茚酮(IC)或二氟代氰基茚酮(2F-IC)末端基团,设计并合成了6个窄带隙的非富勒烯受体材料。 其中,IDTDTP-C₂C₂-H和IDTDTP-C₂C₂-F中的DTP单元以1-乙基丙基为侧链,IDTDTP-C₆C₆-H和IDTDTP-C₆C₆-F中的DTP单元以1-己基庚基为侧链,IDTDTP-C₁₂-H和IDTDTP-C₁₂-F中的DTP单元以十二烷基为侧链。 6个分子均具有较窄的光学带隙(1.37~1.44 eV)。 相比于以IC为末端基团的分子(IDTDTP-C₂C₂-H、IDTDTP-C₆C₆-H和IDTDTP-C₁₂-H),由于氟原子的拉电子效应,以2F-IC为末端基团的分子(IDTDTP-C₂C₂-F、IDTDTP-C₆C₆-F和IDTDTP-C₁₂-F)具有红移的吸收光谱,以及更低的最高分子占有轨道能级(HOMO)和最低分子空轨道(LUMO)能级。 以宽带隙聚合物聚2,6-(4,8-双(5-(2-乙基己基))噻吩-2-基)-苯并1,2-b:4,5-b']二噻吩-alt-5,5-(1',3'-二-2-噻吩)-5',7'-双(2-乙基己基)-苯并1',2'-c:4',5'-c']二噻吩-4,8-二酮](PBDB-T)为给体材料,制备了有机太阳能电池器件。 PBDB-T:IDTDTP-C₆C₆-F共混薄膜具有较高且更平衡的空穴/电子迁移率,以及良好的形貌,基于PBDB-T:IDTDTP-C₆C₆-F的有机太阳能电池获得了6.94%的能量转换效率,开路电压为0.86 V,短路电流密度为13.56 mA/cm²,填充因子为59.5%。

Near-infrared Absorbing Non-fullerene Acceptors with Dithienopyrrole as π Spacer for Organic Solar Cells

A series of non-fullerene acceptors with dithieno3,2-b:2',3'-d]pyrrole(DTP) π bridge to link indacenodithiophene(IDT) core and 3-(dicyanomethylidene)indan-1-one(IC) or difluorinated IC(2F-IC) terminals, i.e. IDTDTP-C₂C₂-H and IDTDTP-C₂C₂-F with 1-ethylpropyl on DTP, IDTDTP-C₆C₆-H and IDTDTP-C₆C₆-F with 1-hexylheptyl on DTP, and IDTDTP-C₁₂-H and IDTDTP-C₁₂-F with n-dodecyl on DTP, was designed and synthesized. These molecules achieved low optical band gaps(1.37~1.44 eV). Compared with the IC-terminated molecules(IDTDTP-C₂C₂-H, IDTDTP-C₆C₆-H and IDTDTP-C₁₂-H), IDTDTP-C₂C₂-F, IDTDTP-C₆C₆-F and IDTDTP-C₁₂-F with 2F-IC as terminals show red-shifted absorption spectra and down-shifted the highest occupied molecular orbitals(HOMO) and the lowest unoccupied molecular orbitals(LUMO) energy levels owing to the electron-withdrawing ability of F substituents. Organic solar cells(OSCs) based on these acceptors were fabricated with the wide-bandgap polymer poly2,6-(4,8-bis(5-(2-ethylhexyl))thiophen-2-yl)-benzo1,2-b:4,5-b']dithiophene-alt-5,5-(1',3'-di-2-thienyl)-5',7'-bis(2-ethylhexyl)-benzo1',2'-c:4',5'-c']dithiophene-4,8-dione](PBDB-T) as the donor. Owing to the higher and more balanced hole and electron mobilities, and a proper phase-separated morphology in the blend film, IDTDTP-C₆C₆-F with 1-hexylheptyl on DTP unit achieved a maximum power conversion efficiency(PCE) of 6.94% with an open-circuit voltage(V_oc) of 0.86 V, a short circuit current density(J_sc) of 13.56 mA/cm² and a fill factor(FF) of 59.5%.