The rational and effective design of nonfullerene acceptors guided by a semi-empirical model for an organic solar cell with an efficiency over 15

• Published in: Journal of materials chemistry. A, Materials for energy and sustainability Materials for energy and sustainability, 2020-05, Vol.8 (19), p.9726-9732
• Main Authors: Ke, Xin, Meng, Lingxian, Wan, Xiangjian, Li, Mingpeng, Sun, Yanna, Guo, Ziqi, Wu, Simin, Zhang, Hongtao, Li, Chenxi, Chen, Yongsheng
• Format: Article
• Language: English
• Subjects: Absorption; Design; Optimization; Photovoltaic cells; Photovoltaics; Polymers; Solar cells; Viscosity
• ISSN: 2050-7488; 2050-7496
• DOI: 10.1039/d0ta03087b

Although much progress has been made in the field of organic photovoltaics (OPVs), the design of active layer materials is generally based on a trial-and-error approach. It is still a challenge to rationally design active layer materials to further improve OPV performance. Herein, guided by a semi-empirical model that we have proposed, two new small-molecule acceptors, named F-2F and FO-2F, were designed and synthesized based on the acceptor F-H. F-2F, having a difluoro-substituted end group, showed absorption red-shifted relative to that of F-H, but still far from the range required in the semi-empirical model. Thus, we performed subtle molecular optimization by inserting an oxygen atom into the backbone of F-2F to design FO-2F, which exhibited much greater red-shifted absorption, close to the preferred absorption range of the semi-empirical model. When blended with the donor polymer PM6, an OPV device based on FO-2F achieved an impressive PCE of 15.05% with a V oc of 0.878 V, a J sc of 22.26 mA cm −2 and a notable FF of 0.77. Both the V oc and J sc values were within the predicted range of the model. These results showed the FO-2F molecule to be a new example of an acceptor yielding a PCE greater than 15%, an achievement previously restricted nearly entirely to the Y6 series. Guided by a semi-empirical model, two small-molecule acceptors were rationally designed and an impressive PCE of 15.05% was achieved.