Chlorinated polymer solar cells simultaneously enhanced by fullerene and non-fullerene ternary strategies

Abstract

Abstract To achieve efficient polymer solar cells (PSCs) with full utilization of the whole spectrum, the multi-component devices are of great importance to be deeply explored, especially for their capability of one-step fabrication. However, the research about one same binary system simultaneously derivated various multi-component PSC is still very limited. Herein, we achieved the whole constructions from one binary host to different ternary systems and even the quaternary one. The ternary strategies with fullerene acceptor, PC71BM, and non-fullerene acceptor, BT6IC-BO-4Cl, as the third component, both boosted the device efficiencies of PBT4Cl-Bz: IT-4F binary system from about 9% to comparatively beyond 11%. Despite the comparable improvement of performance, there existed other similarities and differences in two ternary strategies. In detail, the isotropic carrier transport of PC71BM which largely elevated the fill factor (FF) in the corresponding devices, while the strong absorption of BT6IC-BO-4Cl enhanced the short current density (Jsc) most. More interestingly, quaternary devices based on PBT4Cl-Bz: IT-4F: PC71BM: BT6IC-BO-4Cl could combine both advantages of fullerene and non-fullerene ternary strategies, further pumped the Jsc from 16.44 to the highest level of 19.66 mA cm−2 among all devices, eventually resulted in an optimized efficiency of 11.69%. It reveals that both fullerene and non-fullerene ternary strategies have their unique feature to elevate the device performance either by efficient isotropic carrier transport or better coverage of whole sunlight spectrum and easy tunable energy levels from organic materials. The key is how to integrate the two pathways in one system and provide a more competitive solution facing high-quality PSCs.