以锗为桥接原子的受体材料及其在有机太阳能电池中的应用

Non-fullerene Acceptors with Germanium as Bridge Atom and Their Applications in Organic Solar Cells

有机光伏材料由具有光敏特性的共轭骨架和增溶的烷基侧链组成,而连接两个部分的桥原子对分子的空间构型与材料的光电性质具有重要影响.本文发展了以锗原子为桥接原子的受体材料,并研究了其构效关系.相比于传统的C—C键,更长的C—Ge键改变了烷基侧链与共轭骨架之间的距离,并且影响了共轭骨架的平面性.引入含氟末端基团,通过氟原子诱导的非共价键相互作用对分子构型和固态堆积模式进一步调控.由此设计合成的GD4F-C8材料具有较宽的吸收光谱及合适的能级,并且在薄膜中与聚合物给体PM6的相容性较强,改善了活性层的形貌,基于PM6∶GD4F-C8的有机太阳能电池取得了8.74%的光电转换效率,证明了含锗类材料在有机太阳能电池中的潜力,并为高性能受体材料的开发提供了新思路.

Organic photovoltaic materials are composed of conjugated backbone and alkyl sidechain,which bear the functions of photo-sensitivity and solubilization.The bridge atom which is used to connect the backbone and the sidechain is rarely studied,although it plays a key role in determining molecular geometry and optoelectronic property.Herein,this work developed acceptor materials with germanium bridge and investigates the structure-property relationship.Compared with the traditional C—C bond,the longer C—Ge bond affected the planarity of the conjugated backbone as well as the distance between the backbone and the sidechain.Moreover,the fluorinated terminal was introduced into the acceptor GD4F-C8 to tune molecular geometry and packing order by non-covalent bond interaction which was induced by the fluorine atoms.As a result,GD4F-C8 has a broad absorption spectrum and suitable energy levels.More importantly,the compatibility of GD4F-C8 and the polymer donor PM6 is improved to deliver an active layer with favorable morphology.Eventually,organic solar cells based on PM6∶GD4F-C8 achieves a power conversion efficiency of 8.74%,demonstrating the potential of germanium-containing materials in organic solar cells and providing a new insight for acceptor design.