Germanium- and Silicon-Substituted Donor-Acceptor Type Copolymers: Effect of the Bridging Heteroatom on Molecular Packing and Photovoltaic Device Performance
Germanium- and Silicon-Substituted Donor-Acceptor Type Copolymers: Effect of the Bridging Heteroatom on Molecular Packing and Photovoltaic Device Performance
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DOI：
10.1002/aenm.201400527
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发表时间：
2014-12-29
影响因子：
27.8
通讯作者：
Kim, Ji-Seon
中科院分区：
文献类型：
--
作者：
Kim, Jong Soo;Fei, Zhuping;Kim, Ji-Seon
供体-受体型低带隙共聚物聚[(4,4'-双(2-乙基己基)二噻吩并[3,2-b: 2', 3'-d]硅咯)-2,6-二基-alt-(2,1,3-苯并噻二唑)-4,7-二基] (PSiBTBT)和中硅原子到锗原子的杂原子取代的影响研究了聚[(4,4'-双(2-乙基己基)二噻吩并[3,2-b: 2', 3'-d]germole)-2,6-二基-alt-(2,1,3-苯并噻二唑)-4,7-二基] (PGeBTBT)。研究了这些聚合物的光电和电荷传输特性，特别关注它们与苯基-C-70-丁酸甲酯（PC 70 BM）共混物在有机光伏（OPV）器件中的应用。研究发现，与 C-Si 相比，较长的 C-Ge 键长改变了分子构象，导致 PGeBTBT 比 PSiBTBT 具有更平坦的链构象。分子平面度的增加导致结晶度增强，并且更倾向于正面主链取向，从而导致二极管配置中的载流子迁移率更高。这些结果为了解重原子取代对基于聚[2,6-(4,4-双-(2-乙基己基)-4H-环戊[2,1-b;3,4-b]-二噻吩)-alt-4,7-(2,1,3-苯并噻二唑)(PCPDTBT)主链的聚合物的分子堆积和器件性能的影响提供了重要的见解。
The effects of heteroatom substitution from a silicon atom to a germanium atom in donor-acceptor type low band gap copolymers, poly[(4,4'-bis(2-ethylhexyl) dithieno[3,2-b: 2', 3'-d]silole)-2,6-diyl-alt-(2,1,3-benzothiadiazole)-4,7-diyl] (PSiBTBT) and poly[(4,4'-bis(2-ethylhexyl) dithieno[3,2-b: 2', 3'-d] germole)-2,6-diyl-alt-(2,1,3-benzothiadiazole)-4,7-diyl] (PGeBTBT), are studied. The optoelectronic and charge transport properties of these polymers are investigated with a particular focus on their use for organic photovoltaic (OPV) devices in blends with phenyl-C-70-butyric acid methyl ester (PC 70 BM). It is found that the longer C-Ge bond length, in comparison to C-Si, modifies the molecular conformation and leads to a more planar chain conformation in PGeBTBT than PSiBTBT. This increase in molecular planarity leads to enhanced crystallinity and an increased preference for a face-on backbone orientation, thus leading to higher charge carrier mobility in the diode configuration. These results provide important insight into the impact of the heavy atom substitution on the molecular packing and device performance of polymers based on the poly[2,6-(4,4-bis-(2-ethylhexyl)-4H-cyclopenta[2,1-b; 3,4-b]-dithiophene)-alt-4,7-(2,1,3-benzothiadiazole) (PCPDTBT) backbone.