A Multifluorination Strategy Toward Wide Bandgap Polymers for Highly Efficient Organic Solar Cells

Abstract

AbstractCreating new electron‐deficient unit is highly demanded to develop high‐performance polymer donors for non‐fullerene organic solar cells (OSCs). Herein, we reported a multifluorinated unit 4,5,6,7‐tetrafluoronaphtho[2,1‐b : 3,4‐b′]dithio‐phene (FNT) and its polymers PFNT‐F and PFNT‐Cl. The advantages of multifluorination: (1) it enables the polymers to exhibit low‐lying HOMO (≈−5.5 eV) and wide band gap (≈2.0 eV); (2) the short interactions (F⋅⋅⋅H, F⋅⋅⋅F) endow the polymers with properties of high film crystallinity and efficient hole transport; (3) well miscibility with NFAs that leads to a more well‐defined nanofibrous morphology and face‐on orientation in the blend films. Therefore, the PFNT‐F/Cl : N3 based OSCs exhibit impressive FF values of 0.80, and remarkable PCEs of 17.53 % and 18.10 %, which make them ranked the best donor materials in OSCs. This work offers new insights into the rational design of high‐performance polymers by multifluorination strategy.