Cationic Polyelectrolytes with Alkylsulfonate Counterions as a Cathode Interface Layer for High-Performance Polymer...

Area of Science:

• Materials Science
• Polymer Chemistry
• Renewable Energy

Background:

• Cathode interface layers (CILs) are crucial for efficient charge extraction in polymer solar cells (PSCs).
• Tuning CIL properties can significantly impact PSC performance and stability.
• Developing novel CIL materials is essential for advancing photovoltaic technology.

Purpose of the Study:

• To synthesize and characterize novel PEIE-based CILs with different alkylsulfonate counterions.
• To investigate the effect of counterion size on electron extraction, mobility, and photovoltaic performance in PSCs.
• To establish a strategy for creating light-soaking-free PSCs by optimizing CILs.

Main Methods:

• One-step synthesis of three PEIE-based CILs: PEIE-MSB, PEIE-ESB, and PEIE-BSB.
• Fabrication of single junction bulk heterojunction PSCs using PTB7-Th:PC71BM and PM6:Y6 active layers.
• Characterization of CILs and evaluation of PSC performance, including power conversion efficiency (PCE).

Main Results:

• PEIE-MSB and PEIE-ESB with smaller counterions exhibited superior electron extraction and mobility compared to PEIE-BSB.
• PTB7-Th:PC71BM based PSCs with PEIE-ESB CIL achieved PCEs of 10.44% (8 nm) and 9.23% (30 nm).
• PM6:Y6 based PSCs demonstrated a high PCE of 15.69% with the optimized CIL.

Conclusions:

• Alkylsulfonate counterion size in PEIE-based CILs critically influences PSC performance.
• Smaller counterions lead to enhanced electron extraction and higher power conversion efficiencies.
• This study presents a viable strategy for developing high-performance, light-soaking-free PSCs through CIL modification.