Yan Ye, Liu Yadi, Zhang Qiang, Han Yanchun
State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, China.
School of Applied Chemistry and Engineering, University of Science and Technology of China, Hefei, China.
Front Chem. 2020 May 20;8:394. doi: 10.3389/fchem.2020.00394. eCollection 2020.
The poor electron transport ability of the polymer acceptor is one of the factors restricting the performance of all-polymer solar cells. The percolation network of conjugated polymers can promote its charge transfer. Hence, we aim to find out the critical molecular weight (MW) of N2200 on the forming of the percolation network and to improve its charge mobility and thus photovoltaic performance of J51:N2200 blend. Detailed measurements demonstrate that when the MW of N2200 is larger than 96k, a percolation network structure is formed due to the chain tangled and multi-chain aggregations. Analysis of kinetic experiments reveals that it is the memory of the N2200 long chain conformation and the extent of aggregation in solution are carried into cast films for the formation of the percolation network. Thus, the electron mobility increases from 5.58 × 10 cmVs (N2200) to 9.03 × 10 cmVs when the MW of N2200 is >96k. It led to a balance between hole and electron mobility. The μ/μ decrease from 16.9 to 1.53, causing a significant enhancement in the PCEs, from 5.87 to 8.28% without additives.
聚合物受体较差的电子传输能力是限制全聚合物太阳能电池性能的因素之一。共轭聚合物的渗流网络可以促进其电荷转移。因此，我们旨在找出N2200在形成渗流网络时的临界分子量（MW），并提高其电荷迁移率，从而改善J51:N2200共混物的光伏性能。详细测量表明，当N2200的分子量大于96k时，由于链缠结和多链聚集形成了渗流网络结构。动力学实验分析表明，是N2200长链构象的记忆以及溶液中的聚集程度带入浇铸膜中形成了渗流网络。因此，当N2200的分子量>96k时，电子迁移率从5.58×10 cmVs（N2200）增加到9.03×10 cmVs。这导致了空穴和电子迁移率之间的平衡。μ/μ从16.9降至1.53，在无添加剂的情况下，使功率转换效率（PCEs）从5.87%显著提高到8.28%。
