摘要： Three symmetrically di-fluorinated organic semiconductors (namely D5T2F-P, D5T2F-S, and D5T2F-T) containing rhodanine-flanked pentathiophene structures are synthesized and used as donors in all-small-molecule organic solar cells (ASM-OSCs) prepared with the small-molecule acceptor 2,2'-((2Z,2'Z)-((4,4,9,9-tetrahexyl-4,9-dihydro-s-indaceno[1,2-b:5,6-b']dithiophene-2,7-diyl)bis(methanylylidene))bis(5,6-difluoro-3-oxo-2,3-dihydro-1H-indene-2,1-diylidene))dimalononitrile (IDIC-4F). The different substitutional positions of the fluorine atoms (-F) in the conjugated backbone of the donor molecule leads to various material and photovoltaic properties being exhibited. Among the three isomers, the centrally-fluorinated D5T2F-P exhibits a redshifted absorption spectrum, downshifted highest occupied molecular orbital (HOMO) energy level, and improved miscibility with IDIC-4F in the blend films, all of which result in superior device performance. The power conversion efficiency (PCE) of the ASM-OSCs based on D5T2F-P:IDIC-4F reaches the impressive value of 9.36% with an open-circuit voltage (VOC) value of 0.86 V and a short-circuit current density (JSC) value of 16.94 mA/cm2, while those of D5T2F-S (6.11%) and D5T2F-T (5.42%) are much lower. In comparison, an ASM-OSC based on the non-fluorinated analogue DRCN5T fabricated under the same conditions exhibits poorer performance (8.03% with IDIC-4F), revealing a 16% enhancement in PCE achieved through backbone fluorination. To the best of our knowledge, the PCE of 9.36% is one of the highest efficiencies of oligothiophene-based ASM-OSCs reported in the literature to date.