Polymer Acceptor Based on B←N Units with Enhanced Electron Mobility for Efficient All-Polymer Solar Cells

Area of Science:

• Materials Science
• Organic Electronics
• Photovoltaics

Background:

• All-polymer solar cells (all-PSCs) offer advantages like mechanical flexibility and low-cost processing.
• Developing efficient polymer electron acceptors remains a key challenge for high-performance all-PSCs.
• Existing polymer acceptors often suffer from limited electron mobility due to steric hindrance.

Purpose of the Study:

• To develop novel polymer electron acceptors for all-polymer solar cells (all-PSCs).
• To investigate the impact of B←N units on polymer backbone structure and electronic properties.
• To enhance the power conversion efficiency (PCE) of all-PSCs using these new acceptors.

Main Methods:

• Synthesis of conjugated polymers incorporating B←N units.
• Characterization of polymer structure, including π-π stacking distance and steric hindrance.
• Measurement of electron mobility in polymer films.
• Fabrication and testing of all-PSC devices using the developed polymers as electron acceptors.

Main Results:

• Polymers with B←N units effectively alleviate steric hindrance in pendant moieties.
• Reduced π-π stacking distance leads to a nearly two-orders-of-magnitude enhancement in electron mobility.
• All-PSCs utilizing these polymers as electron acceptors achieved a power conversion efficiency (PCE) of 5.04%, a significant improvement from 0.12%.

Conclusions:

• B←N units are a promising strategy for designing high-performance polymer electron acceptors.
• Alleviating steric hindrance is crucial for enhancing electron mobility and device performance in all-PSCs.
• The developed polymer acceptors demonstrate performance competitive with state-of-the-art materials.