Over 14% Efficiency in Organic Solar Cells Enabled by Chlorinated Nonfullerene Small-Molecule Acceptors
Over 14% Efficiency in Organic Solar Cells Enabled by Chlorinated Nonfullerene Small-Molecule Acceptors
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DOI：
10.1002/adma.201800613
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发表时间：
2018-07-12
影响因子：
29.4
通讯作者：
Hou, Jianhui
中科院分区：
文献类型：
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作者：
Zhang, Hao;Yao, Huifeng;Hou, Jianhui
为了使有机太阳能电池（osc）在各种光伏电池技术中更具竞争力，证明osc可以实现非常好的效率并且可以降低成本是非常重要的。本文通过在吲哚二噻吩[3,2-b]单元上引入易于合成的氯取代基，设计并合成了一对非富勒烯小分子受体IT-2Cl和IT-4Cl。C-Cl键的大偶极矩的独特特性增强了供体-受体结构之间的分子间电荷转移效应，从而扩大了吸收并降低了分子能级。同时，C-Cl的引入也使分子堆积更加明显，这也有助于扩大吸收光谱。设计的基于两种受体的OSCs器件，当与具有低占据分子轨道最高能级的聚合物供体混合时，其功率转换效率（PCE）均大于13%。此外，由于IT-2Cl和IT-4Cl具有很好的相容性，我们还制作了一种集成这两种受体的三元OSC器件，其PCE大于14%。氯化处理在提高器件性能和简化合成路线方面表现出了有效的能力，在光伏材料改性方面值得进一步开发。
To make organic solar cells (OSCs) more competitive in the diverse photovoltaic cell technologies, it is very important to demonstrate that OSCs can achieve very good efficiencies and that their cost can be reduced. Here, a pair of nonfullerene small-molecule acceptors, IT-2Cl and IT-4Cl, is designed and synthesized by introducing easy-synthesis chlorine substituents onto the indacenodithieno[3,2-b]thiophene units. The unique feature of the large dipole moment of the C-Cl bond enhances the intermolecular charge-transfer effect between the donor-acceptor structures, and thus expands the absorption and down shifts the molecular energy levels. Meanwhile, the introduction of C-Cl also causes more pronounced molecular stacking, which also helps to expand the absorption spectrum. Both of the designed OSCs devices based on two acceptors can deliver a power conversion efficiency (PCE) greater than 13% when blended with a polymer donor with a low-lying highest occupied molecular orbital level. In addition, since IT-2Cl and IT-4Cl have very good compatibility, a ternary OSC device integrating these two acceptors is also fabricated and obtains a PCE greater than 14%. Chlorination demonstrates effective ability in enhancing the device performance and facile synthesis route, which both deserve further exploitation in the modification of photovoltaic materials.