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

Abstract

Creating 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.

Directly Cross‐Linked Conjugated Polymer Donor Enables Efficient Polymer Solar Cells with Extraordinary Mechanical Robustness

“…[1][2][3][4] The rapid development of conjugated polymer donors combined with non-fullerene acceptors (NFAs) has engaged encouraging progress, with the best power conversion efficiencies (PCEs) of the single-junction PSCs over 18%. [5][6][7][8][9] Among these effective conjugated polymer donors, donor-acceptor (D-A) type conjugated copolymers have been proven to be one of the most successful strategies for PSCs. [10] The strong intramolecular charge transfer, co-facial 𝜋-𝜋 stacking, and side chain interactions are beneficial to narrowing the energy gap and improving the hole transport of the polymers.…”

“…[ 1–4 ] The rapid development of conjugated polymer donors combined with non‐fullerene acceptors (NFAs) has engaged encouraging progress, with the best power conversion efficiencies (PCEs) of the single‐junction PSCs over 18%. [ 5–9 ]…”

Trifluoromethylation in the Design and Synthesis of High-Performance Wide Bandgap Polymer Donors for Quasiplanar Heterojunction Organic Solar Cells

“…Electron-deficient units effectively modulate the film morphology, optical bandgap, and frontier orbital energy level , properties, which play an important role in enhancement of the PCE. Historically, the halogenation of polymer donors , has emerged as the most efficient strategy with which to improve photovoltaic performance.…”

Manipulating the Alkyl Chains of Naphthodithiophene Imide-Based Polymers to Concurrently Boost the Efficiency and Stability of Organic Solar Cells

“…In the blend film, the separated NFA domains are dispersed between the interconnecting polymer domains and the physical property of the polymer donor should play a key role in the morphology stability of the interpenetrating D/A domains. − However, very limited attention was paid to study the relationship between the polymer structure, crystallinity, and morphology stability, although it is crucially important. ,, Consequently, how to design polymer donors with high efficiency and excellent morphology stability remains challenging currently. The chemical structure of the monomer significantly affects the intermolecular interaction, crystallinity, and film forming properties of polymers. − The units with a large conjugated backbone benefit strong intermolecular interactions, which probably could provide additional strength against polymer chain movement. − Therefore, developing polymer donors based on multifused aromatic units should be a wise option to address the morphology stability issue of OSCs.…”