Yao Zhaoyang, Cao Xiangjian, Bi Xingqi, He Tengfei, Li Yu, Jia Xinyuan, Liang Huazhe, Guo Yaxiao, Long Guankui, Kan Bin, Li Chenxi, Wan Xiangjian, Chen Yongsheng
State Key Laboratory and Institute of Elemento-Organic Chemistry, The Centre of Nanoscale Science and Technology and Key Laboratory of Functional Polymer Materials, Renewable Energy Conversion and Storage Center (RECAST), College of Chemistry, Nankai University, Tianjin, 300071, China.
State Key Laboratory of Separation Membranes and Membrane Processes, School of Chemistry, Tiangong University, Tianjin, 300387, China.
Angew Chem Int Ed Engl. 2023 Oct 26;62(44):e202312630. doi: 10.1002/anie.202312630. Epub 2023 Sep 25.
Due to the intrinsically flexible molecular skeletons and loose aggregations, organic semiconductors, like small molecular acceptors (SMAs) in organic solar cells (OSCs), greatly suffer from larger structural/packing disorders and weaker intermolecular interactions comparing to their inorganic counterparts, further leading to hindered exciton diffusion/dissociation and charge carrier migration in resulting OSCs. To overcome this challenge, complete peripheral fluorination was performed on basis of a two-dimensional (2D) conjugation extended molecular platform of CH-series SMAs, rendering an acceptor of CH8F with eight fluorine atoms surrounding the molecular backbone. Benefitting from the broad 2D backbone, more importantly, strengthened fluorine-induced secondary interactions, CH8F and its D18 blends afford much enhanced and more ordered molecular packings accompanying with enlarged dielectric constants, reduced exciton binding energies and more obvious fibrillary networks comparing to CH6F controls. Consequently, D18:CH8F-based OSCs reached an excellent efficiency of 18.80 %, much better than that of 17.91 % for CH6F-based ones. More excitingly, by employing D18-Cl that possesses a highly similar structure to D18 as a third component, the highest efficiency of 19.28 % for CH-series SMAs-based OSCs has been achieved so far. Our work demonstrates the dramatical structural multiformity of CH-series SMAs, meanwhile, their high potential for constructing record-breaking OSCs through peripheral fine-tuning.
由于具有内在的柔性分子骨架和松散的聚集结构，有机半导体，如有机太阳能电池（OSC）中的小分子受体（SMA），与无机半导体相比，存在更大的结构/堆积无序和更弱的分子间相互作用，这进一步导致了所得OSC中激子扩散/解离和电荷载流子迁移受阻。为了克服这一挑战，在CH系列SMA的二维（2D）共轭扩展分子平台的基础上进行了完全外围氟化，得到了一种CH8F受体，其分子主链周围有八个氟原子。得益于宽广的二维主链，更重要的是，强化的氟诱导二级相互作用，与CH6F对照相比，CH8F及其D18共混物具有增强得多且更有序的分子堆积，同时介电常数增大，激子结合能降低，纤维状网络更明显。因此，基于D18:CH8F的OSC达到了18.80%的优异效率，远高于基于CH6F的OSC的17.91%。更令人兴奋的是，通过使用与D18结构高度相似的D18-Cl作为第三组分，目前基于CH系列SMA的OSC实现了19.28%的最高效率。我们的工作展示了CH系列SMA显著的结构多样性，同时也展示了它们通过外围微调构建破纪录OSC的巨大潜力。
