Zhang Wenjing, Wu Yue, Ma Ruijie, Fan Hongyu, Li Xiaoxiao, Yang Hang, Cui Chaohua, Li Yongfang
Laboratory of Advanced Optoelectronic Materials, Suzhou Key Laboratory of Novel Semiconductor-Optoelectronics Materials and Devices, College of Chemistry Chemical Engineering and Materials Science, Soochow University Jiangsu, Suzhou, 215123, China.
Department of Electronic and Information Engineering Research Institute for Smart Energy (RISE), The Hong Kong Polytechnic University, Hong Kong, 999077, China.
Angew Chem Int Ed Engl. 2023 Oct 23;62(43):e202309713. doi: 10.1002/anie.202309713. Epub 2023 Sep 19.
Regulating molecular packing and aggregation of photoactive layer is a critical but challenging issue in developing high-performance organic solar cells. Herein, two structurally similar analogues of anthra[2,3-b : 6,7-b']dithiophene (ADT) and naphtho[1,2-b : 5,6-b']dithiophene (NDT) are developed as solid additive to exploit their effect in regulating the molecular aggregation and π-stacking of photoactive layer. We clarify that the perpendicular arrangements of NDT can enlarge the molecular packing space and improve the face-on stacking of Y6 during the film formation, favoring a more compact and ordered long-range π-π stacking in the out-of-plane direction after the removal of NDT under thermal annealing. The edge-to-face stacked herringbone-arrangement of ADT along with its non-volatilization under thermal annealing can induce the coexistence of face-on and edge-on stacking of blend film. As a result, the NDT treatment shows encouraging effect in improving the photovoltaic performance of devices based on various systems. Particularly, a remarkable PCE of 18.85 % is achieved in the PM6 : L8-BO-based device treated by NDT additive, which is a significant improvement with regard to the PCE of 16.41 % for the control device. This work offers a promising strategy to regulate the molecular packing and aggregation of photoactive layer towards significantly improved performance and stability of organic solar cells.
在开发高性能有机太阳能电池时，调节光活性层的分子堆积和聚集是一个关键但具有挑战性的问题。在此，开发了两种结构相似的蒽[2,3-b : 6,7-b']二噻吩（ADT）和萘并[1,2-b : 5,6-b']二噻吩（NDT）类似物作为固体添加剂，以研究它们在调节光活性层分子聚集和π堆积方面的作用。我们阐明，NDT的垂直排列可以扩大分子堆积空间，并在成膜过程中改善Y6的面朝上堆积，有利于在热退火下去除NDT后，在面外方向形成更紧凑、有序的长程π-π堆积。ADT的边对面堆叠的人字形排列及其在热退火下的不挥发会导致共混膜面朝上和边朝上堆积的共存。结果，NDT处理在改善基于各种体系的器件的光伏性能方面显示出令人鼓舞的效果。特别是，在经NDT添加剂处理的基于PM6 : L8-BO的器件中实现了18.85 %的显著功率转换效率（PCE），相对于对照器件16.41 %的PCE有显著提高。这项工作为调节光活性层的分子堆积和聚集提供了一种有前景的策略，以显著提高有机太阳能电池的性能和稳定性。
