Vertically optimized phase separation with improved exciton diffusion enables efficient organic solar cells with thick active layers

Yunhao Cai; Qian Li; Guanyu Lu; Hwa Sook Ryu; Yun Li; Hui Jin; Zhihao Chen; Zheng Tang; Guanghao Lu; Xiaotao Hao; Han Young Woo; Chunfeng Zhang; Yanming Sun

doi:10.1038/s41467-022-29803-6

Vertically optimized phase separation with improved exciton diffusion enables efficient organic solar cells with thick active layers

Nat Commun. 2022 May 2;13(1):2369. doi: 10.1038/s41467-022-29803-6.

Authors

Yunhao Cai¹, Qian Li², Guanyu Lu³, Hwa Sook Ryu⁴, Yun Li¹, Hui Jin⁵, Zhihao Chen⁶, Zheng Tang⁵, Guanghao Lu⁷, Xiaotao Hao⁶, Han Young Woo⁴, Chunfeng Zhang⁸, Yanming Sun^{9

10}

Affiliations

¹ School of Chemistry, Beihang University, 100191, Beijing, P. R. China.
² National Laboratory of Solid State Microstructures, School of Physics, and Collaborative Innovation Center for Advanced Microstructures, Nanjing University, Nanjing, 210093, P. R. China.
³ Frontier Institute of Science and Technology, Xi'an Jiaotong University, Xi'an, 710054, P. R. China.
⁴ Department of Chemistry, College of Science, KU-KIST Graduate School of Converging Science and Technology, Korea University, Seoul, 136-713, Republic of Korea.
⁵ State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, Center for Advanced Low-dimension Materials, College of Materials Science and Engineering, Donghua University, Shanghai, 201620, P. R. China.
⁶ School of Physics State Key Laboratory of Crystal Materials, Shandong University, Jinan, 250100, P. R. China.
⁷ Frontier Institute of Science and Technology, Xi'an Jiaotong University, Xi'an, 710054, P. R. China. guanghao.lu@mail.xjtu.edu.cn.
⁸ National Laboratory of Solid State Microstructures, School of Physics, and Collaborative Innovation Center for Advanced Microstructures, Nanjing University, Nanjing, 210093, P. R. China. cfzhang@nju.edu.cn.
⁹ School of Chemistry, Beihang University, 100191, Beijing, P. R. China. sunym@buaa.edu.cn.
¹⁰ Beijing Advanced Innovation Center for Biomedical Engineering, 100191, Beijing, China. sunym@buaa.edu.cn.

Abstract

The development of organic solar cells (OSCs) with thick active layers is of crucial importance for the roll-to-roll printing of large-area solar panels. Unfortunately, increasing the active layer thickness usually results in a significant reduction in efficiency. Herein, we fabricated efficient thick-film OSCs with an active layer consisting of one polymer donor and two non-fullerene acceptors. The two acceptors were found to possess enlarged exciton diffusion length in the mixed phase, which is beneficial to exciton generation and dissociation. Additionally, layer by layer approach was employed to optimize the vertical phase separation. Benefiting from the synergetic effects of enlarged exciton diffusion length and graded vertical phase separation, an efficiency of 17.31% (certified value of 16.9%) is obtained for the 300 nm-thick OSC, with a short-circuit current density of 28.36 mA cm^-2, and a high fill factor of 73.0%. Moreover, the device with an active layer thickness of 500 nm also shows an efficiency of 15.21%. This work provides valuable insights into the fabrication of OSCs with thick active layers.