High-Performance All-Polymer Solar Cells Enabled by an n-Type Polymer Based on a Fluorinated Imide-Functionalized...

Area of Science:

• Materials Science
• Organic Electronics
• Photovoltaics

Background:

• Developing high-performance n-type semiconductors is crucial for organic electronics.
• Fluorination of electron-deficient acceptors enhances their properties for n-type polymers.
• Existing naphthalene diimide and perylene diimide-based polymers have limitations.

Purpose of the Study:

• To design and synthesize a novel imide-functionalized arene, di(fluorothienyl)thienothiophene diimide (f-FBTI2).
• To investigate the optoelectronic properties of polymers incorporating f-FBTI2.
• To evaluate the performance of f-FBTI2 in all-polymer solar cells.

Main Methods:

• Synthesis of the novel f-FBTI2 molecule.
• Incorporation of f-FBTI2 into a polymer (f-FBTI2-T).
• Fabrication and characterization of all-polymer solar cells using f-FBTI2-T as the acceptor.

Main Results:

• Successfully synthesized f-FBTI2, overcoming challenges with highly electron-deficient fluorinated imides.
• f-FBTI2-T exhibited a reduced bandgap and lower LUMO energy level compared to non-fluorinated analogs.
• All-polymer solar cells achieved a power conversion efficiency of 8.1% without additives or thermal treatment.
• The solar cells demonstrated a record low energy loss of 0.53 eV for efficiencies exceeding 8%.

Conclusions:

• Fluorination of imide-functionalized arenes is an effective strategy for creating advanced electron-deficient building blocks.
• f-FBTI2 is a promising material for developing high-performance n-type polymers.
• This work significantly advances the field of all-polymer solar cells.