Blending Donors with Different Molecular Weights: An Efficient Strategy to Resolve the Conflict between Coherence Length and Intermixed Phase in Polymer/Nonfullerene Solar Cells
Blending Donors with Different Molecular Weights: An Efficient Strategy to Resolve the Conflict between Coherence Length and Intermixed Phase in Polymer/Nonfullerene Solar Cells
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混合不同分子量的供体：解决聚合物/非富勒烯太阳能电池相干长度和混合相之间冲突的有效策略
DOI：
10.1002/smll.202103804
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发表时间：
2021-11-25
期刊：
影响因子：
13.3
通讯作者：
Huang, Wei
中科院分区：
文献类型：
--
作者：
Liang, Qiuju;Hu, Zhangbo;Huang, Wei
长的晶体相干长度和合适的混合相含量保证了晶体中电荷的有效传输和激子的有效解离，是有机太阳能电池获得高性能的关键。然而，延长CL通常会减少混合相，导致激子解离的界面不足。在此，采用使用具有不同分子量的二元聚合物作为供体的策略，即聚将具有高（P3 HT-H）和低（P3 HT-L）分子量的（3-己基噻吩-2，5-二基）（P3 HT）共混作为供体，（5Z，5 ' Z）-5，5'-（4，4，9，9-四辛基-4，9-二氢-s-引达省并[1，2-B：5，6-B ']二噻吩-2，7-二基）双（苯并[c][1，2，5]噻二唑-7，4-二基））双（亚甲基））双（3-乙基-2-硫代噻唑烷-4-酮）（O-IDTBR）用作受体。在动力学方面，由于P3 HT-L具有较高的分子扩散系数，P3 HT-H的缠结得到缓解。热力学上，P3 HT-L/O-IDTBR、P3 HT-H/O-IDTBR和P3 HT-L/P3 HT-H共混物的相容性依次增大。因此，添加P3 HT-L后，P3 HT形成了更有序的结构，具有更长的CL，这也促使分散在P3 HT晶区的O-IDTBR扩散到O-IDTBR晶区，进一步自组织。因此，P3 HT和O-IDTBR的CL都得到了扩展，同时保持了适当的混合相量。优化的微结构将器件性能从7.03%提高到7.80%，这是P3 HT/O-IDTBR共混物报道的最高值之一。这是解决上述矛盾的一种新方法，可为精细调节有源层的形貌提供指导。
Long coherence lengths (CLs) of crystals and proper intermixed phase amount guarantee charge transport and exciton dissociate efficiently, which is crucial for organic solar cells (OSCs) to achieve high device performance. However, extending CLs usually reduces the intermixed phase, leading to an insufficient interface for exciton dissociation. Herein, a strategy using a binary polymer with different molecular weights as donor is employed, that is, poly(3-hexylthiophene-2,5-diyl) (P3HT) with high (P3HT-H) and low (P3HT-L) molecular weight are blended as donor, and (5Z,5 ' Z)-5,5 '-(((4,4,9,9-tetraoctyl-4,9-dihydro-s-indaceno[1,2-b:5,6-b ']dithiophene-2,7-diyl)bis(benzo[c][1,2,5]thiadiazole-7,4-diyl))bis(methanylylidene))bis(3-ethyl-2-thioxothiazolidin-4-one) (O-IDTBR) is used as acceptor. In kinetics, the entanglements of P3HT-H are relieved due to the higher molecular diffusivity of P3HT-L. In thermodynamics, the miscibility of P3HT-L/O-IDTBR, P3HT-H/O-IDTBR, and P3HT-L/P3HT-H blends increases in turn. Hence, P3HT forms a more ordered structure with longer CLs after adding P3HT-L, which also drives O-IDTBR dispersed in P3HT crystalline regions diffuse to the O-IDTBR crystalline regions to further self-organize. Consequently, the CLs of both P3HT and O-IDTBR are extended, while keeping the intermixed phase amount proper. The optimized microstructure boosts device performance from 7.03% to 7.80%, which is one of the highest values reported for P3HT/O-IDTBR blends. This is a novel way to solve the conflict mentioned above, which may provide guidance to finely regulating the morphology of the active layer.