Biselenophene Imide: Enabling Polymer Acceptor with High Electron Mobility for High-Performance All-Polymer Solar...

Area of Science:

• Materials Science
• Organic Electronics
• Photovoltaics

Background:

• Efficient all-polymer solar cells (all-PSCs) are hindered by a lack of narrow band gap polymer acceptors with high electron mobility.
• Developing advanced polymer acceptors is crucial for improving all-PSC performance and overcoming current limitations.

Purpose of the Study:

• To synthesize a novel distannylated electron-deficient biselenophene imide monomer (BSeI-Tin) for creating high-performance acceptor-acceptor (A-A) type polymer acceptors.
• To investigate the properties and performance of A-A type polymers derived from BSeI-Tin in all-PSCs.

Main Methods:

• Synthesis of a high-purity and high-reactivity distannylated electron-deficient biselenophene imide monomer (BSeI-Tin).
• Copolymerization of BSeI-Tin with a dibrominated monomer (Y5-Br) to form the A-A type polymer PY5-BSeI.
• Fabrication and characterization of all-polymer solar cells (all-PSCs) using the synthesized PY5-BSeI polymer.

Main Results:

• The A-A polymer PY5-BSeI exhibited higher molecular weight, a narrower band gap, deeper frontier molecular orbital levels, and enhanced electron mobility compared to its donor-acceptor counterpart.
• PY5-BSeI-based all-PSCs achieved a remarkable power conversion efficiency of 17.77%, with a high short-circuit current (24.93 mA cm⁻²) and fill factor (75.83%).
• This efficiency significantly surpasses the 10.70% efficiency of devices based on the PY5-BSe polymer.

Conclusions:

• Biselenophene imide (BSeI) is identified as a promising building block for high-performance polymer acceptors in all-PSCs.
• Stannylation of electron-deficient building blocks provides an effective strategy for developing A-A type polymers for advanced all-polymer solar cells and other organic electronic applications.