High-Performance Electron Acceptor with Thienyl Side Chains for Organic Photovoltaics

Area of Science:

• Materials Science
• Organic Electronics
• Photovoltaics

Background:

• Organic solar cells (OSCs) offer a promising alternative to traditional silicon-based photovoltaics due to their flexibility and low-cost manufacturing potential.
• Developing efficient non-fullerene acceptors is crucial for advancing OSC performance.
• Existing acceptors often face limitations in energy level tuning and charge transport properties.

Purpose of the Study:

• To design and synthesize a novel fused-ring electron acceptor, ITIC-Th, for high-performance organic solar cells.
• To investigate the impact of thienyl side-chains on the electronic properties and performance of the acceptor.
• To evaluate the efficiency of OSCs fabricated with ITIC-Th in conjunction with different polymer donors.

Main Methods:

• Synthesis of the ITIC-Th fused-ring electron acceptor.
• Characterization of the electronic properties (HOMO/LUMO energy levels) and electron mobility of ITIC-Th.
• Fabrication of organic solar cells using ITIC-Th blended with narrow-band-gap and wide-band-gap polymer donors.
• Performance evaluation of the fabricated OSCs, including power conversion efficiency (PCE).

Main Results:

• ITIC-Th exhibits lower energy levels (HOMO = -5.66 eV, LUMO = -3.93 eV) compared to its phenyl-substituted counterpart (ITIC).
• The thienyl side-chains induce a σ-inductive effect, enabling better energy level alignment with polymer donors.
• ITIC-Th demonstrates significantly higher electron mobility (6.1 × 10⁻⁴ cm² V⁻¹ s⁻¹) than ITIC (2.6 × 10⁻⁴ cm² V⁻¹ s⁻¹).
• OSCs fabricated with ITIC-Th achieved a power conversion efficiency of 9.6%.

Conclusions:

• ITIC-Th is an efficient fused-ring electron acceptor for organic solar cells.
• The design incorporating thienyl side-chains enhances electron mobility and facilitates energy level matching.
• The achieved 9.6% efficiency highlights the potential of ITIC-Th as a high-performance non-fullerene acceptor, competitive with fullerene-based systems.