Three n-OS acceptors with E_g values of <1.4 eV were synthesized by introducing double-bond π-bridges into ITIC (ITVIC) and ITIC with monofluorine (ITVfIC) or bifluorine (ITVffIC) substituents on its end groups, and the structure–property relationships of the acceptors were systematically studied. The three n-OS films show broad absorption covering the wavelength range of 550–900 nm with narrow E_g values of 1.40 eV for ITVIC, 1.37 eV for ITVfIC, and 1.35 eV for ITVffIC. Additionally, the fluorine substitution downshifted the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energy levels of the compounds. The photovoltaic properties of the n-OS acceptors were investigated by using a medium bandgap conjugated polymer J71 as a donor. The optimized polymer solar cells (PSCs) based on J71:ITVffIC demonstrated a power conversion efficiency (PCE) of 10.54% with a high J_sc of 20.60 mA cm^–2 and a V_oc of 0.81 V, and the highest J_sc reached 22.83 mA cm^–2. The high J_sc values of the devices could be attributed to the broad absorption and lower-lying HOMO energy levels of the acceptor. Considering the V_oc of 0.81 V and the narrow bandgap of 1.35 eV for the acceptor ITVffIC, we found the energy loss (E_loss) of the ITVffIC-based PSCs was reduced to 0.54 eV, which is the lowest value in the PSCs with a PCE of >10%. The results indicate that ITVffIC is a promising narrow E_g acceptor for application in tandem and semitransparent PSCs.

中文翻译：

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一系列窄带隙有机半导体受体的吸收边缘达到900 nm的合成及其光伏性能

通过将双键π桥引入ITIC（ITVIC）和末端带有单氟（ITVfIC）或双氟（ITVffIC）取代基的ITIC，合成了三个E _g值小于1.4 eV的n -OS受体，其结构为对受体的性质关系进行了系统的研究。三个Ñ -OS膜显示宽的吸收覆盖的具有窄550-900纳米的波长范围内ë_克1.40电子伏特为ITVIC，1.37电子伏特为ITVfIC，和1.35电子伏特为ITVffIC的值。此外，氟取代使化合物的最高占据分子轨道（HOMO）和最低未占据分子轨道（LUMO）能级降低。n的光伏特性通过使用中等带隙共轭聚合物J71作为供体研究-OS受体。基于J71：ITVffIC的优化聚合物太阳能电池（PSC）表现出10.54％的功率转换效率（PCE），具有20.60 mA cm ^–2的高J _sc和0.81 V的V _oc，最高的J _sc达到22.83毫安厘米^–2。装置的高J _sc值可归因于受体的广泛吸收和较低的HOMO能级。考虑受体ITVffIC的V _oc为0.81 V和窄带隙为1.35 eV，我们发现能量损失（E_损失）的基于ITVffIC的PSC降低到0.54 eV，这是PCE> 10％的PSC中的最低值。结果表明，ITVffIC是用于串联和半透明PSC的有希望的窄E _g受体。