巯基聚芴材料合成及其在太阳电池界面修饰层中的应用

In the past two years, polymer solar cells(PSC) have realized 8-9% power conversion efficiency (PCE),and the researchers believe that power conversion efficiency (PCE) will achieve 15% in the next few years. Besides the donor/acceptor synthesis and device optimization,the interlayer is also one of the most important research fields. Polymer solar cells with electrode interlayer can improve the power conversion efficiencies （PCE）, open-circuit voltage (Voc), short-circuit current density (Jsc) and fill factor(FF)simultaneously.Up to now, devices with interlayer is one of the methods to realize the world record PCE in PSC research. The ammonium based polyfluorene (PFN) interlayer works well for aluminum electrode based solar cells devices, but the build-in potential between PFN/Al is around 0.2-0.3V and the electron mobility of PFN is low. The researchers should continue to increase build-in potential in the interface and improve the electron mobility of the interlayer materials. So our proposal is to introduce thiol into the polyfluorene (PF)sidechain and high electron mobility segment in the backbone.The thiol group will have strong effect with high work-function electrode (Au or Ag)of PSC.By copolymerization, we can modulate the energy band gap,energy level and electon moblility of the thiol modified polyfluorene （PFT）to make it a suitable interlayer material for PSC with Au or Ag electrode.The polymer can modify the Au or Ag electrode work-function,improve the interaction between the semiconductor layer and metal elecctrode, lower the interface barrier and increase the build-in potentials in solar cells devices (around 0.5V) and improve the PSC performances. We hope the thiol modified polyfluorene will be the most important PSC interlayer materials for Au or Ag electrode based devices,and we can further improve PSC perforamance by this thiol modified polyfluoene materials to 9-10% PCE.

最近1-2年内，聚合物太阳电池实现了8-9％的能量转化效率，研究者坚信商业化的15％能量转化效率的聚合物太阳电池即将实现。最近的研究表明，除了新型给受体的材料合成与器件优化外，界面材料也是非常重要的研究方向。通过采用界面材料修饰，能够同时提高器件的开路电压、短路电流、填充因子和能量转化效率。本课题针对广泛研究的氨基聚芴/铝复合电极，提出巯基聚芴/金复合电极作为聚合物太阳电池阴极，预期巯基聚芴/金复合电极能提供比氨基聚芴/铝复合电极更高的电偶极矩，进而提高电池器件的开路电压约0.2V。另外，针对广泛研究的氨基聚芴作为修饰材料，电子迁移率不高，影响器件性能的问题，我们提出在巯基聚合物中引入强的吸电子基团，提高其电子迁移率，进而提高聚合物太阳电池性能。我们预计通过上述两种方法，可提高聚合物太阳电池性能约10－20％左右，将PTB7体系（一种最高效率聚合物太阳电池材料）实现9-10％能量转换效率。

本项目设计合成了若干中含有极性基团的芴基聚合物材料，并尝试将其用于聚合物太阳电池界面修饰层，实现了超过了10％能量转化效率的聚合物太阳电池器件。设计合成的溶液加工小分子界面修饰材料和聚苯胺材料作为界面层的器件也实现了超过9％能量转化效率的聚合物太阳电池器件。采用苯并二噻吩材料作为钙钛矿太阳电池修饰层器件也实现约10％的光电效率。此外为了实现与合成的界面层匹配的活性层材料，本课题也开展了聚合物太阳电池活性层材料，特别是给体材料合成工作，包括苯并二噻吩、IDT、噻吩等聚合物，通过引入不同侧链和共聚不同单元，调节聚合物材料带隙能级和在器件薄膜中的聚积态结构，进而优化聚合物太阳电池器件性能。同时，项目开展了部分溶液加工小分子太阳电池给体材料的合成工作。项目的完成得到了包括中国科学院青岛生物能源与过程研究所阳仁强研究员、中国科学院化学研究所侯剑辉研究员、香港城市大学李振声教授和V. A. L. Roy副教授等课题组的大力协助。