Precise fluorination of polymeric donors towards efficient non-fullerene organic solar cells with balanced open circuit voltage, short circuit current and fill factor

Xiaosha Wang; Honggang Chen; Jun Yuan; Qingya Wei; Jing Li; Lihui Jiang; Jun Huang; Yongfang Li; Yungui Li; Yingping Zou

doi:10.1039/D1TA01500A

Precise fluorination of polymeric donors towards efficient non-fullerene organic solar cells with balanced open circuit voltage, short circuit current and fill factor†

Xiaosha Wang,‡^a Honggang Chen,‡^a Jun Yuan,^a Qingya Wei,^a Jing Li,^a Lihui Jiang,

*^ab Jun Huang,^c Yongfang Li,

^d Yungui Li*^e and Yingping Zou

*^a

Author affiliations

* Corresponding authors

^a College of Chemistry and Chemical Engineering, Central South University, Changsha 410083, China
E-mail: jianglh@csu.edu.cn, yingpingzou@csu.edu.cn

^b State Key Laboratory of Luminescent Materials and Devices, South China University of Technology, Guangzhou 510640, China

^c Center for Advanced Low-dimension Materials, State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, Donghua University, Shanghai 201620, China

^d Beijing National Laboratory for Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China

^e Max-Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
E-mail: liy@mpip-mainz.mpg.de

Abstract

Three polymer donors named Qx-8F, Qx-10F, and Qx-12F, with similar chemical structures, were synthesized. The energy level of these donors is manipulated by precisely controlling the fluorination sites. We demonstrate that the exciton dissociation efficiency is gradually enhanced from Qx-8F:Y6 to Qx-12F:Y6, leading to improved open circuit voltage V_OC and short circuit current density J_SC for donors with a higher degree of fluorination. Simultaneously, the trap-assisted recombination or bimolecular recombination intensity is reduced, while the extraction rate is enhanced because of increased charge carrier mobilities, leading to an increase in fill factor for donors with higher amount of fluorine atoms. The optimized device based on Qx-12F with the most fluorine atoms and the non-fullerene acceptor Y6 shows the highest power conversion efficiency of 15.21%, with a V_OC of 0.85 V, J_SC of 24.55 mA cm⁻², and fill factor of 72.88%. It is further demonstrated that the optimized ternary device based on the Qx-12F:PM6:Y6 blend provides a power conversion efficiency of 16.32%.

Journal of Materials Chemistry A

Precise fluorination of polymeric donors towards efficient non-fullerene organic solar cells with balanced open circuit voltage, short circuit current and fill factor†

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Precise fluorination of polymeric donors towards efficient non-fullerene organic solar cells with balanced open circuit voltage, short circuit current and fill factor

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