High-Efficiency Binary and Ternary Organic Solar Cells Based on Novel Nonfused-Ring Electron Acceptors

Area of Science:

• Materials Science
• Organic Electronics
• Photovoltaics

Background:

• Organic solar cells (OSCs) offer a promising alternative to traditional silicon photovoltaics due to their flexibility and low-cost fabrication.
• Developing efficient nonfused-ring electron acceptors is crucial for advancing OSC performance.

Purpose of the Study:

• To design and synthesize novel nonfused-ring electron acceptors with varying terminal groups and side chains.
• To investigate the impact of electron-withdrawing and lateral alkyl side chains on OSC performance.
• To evaluate the potential of these acceptors in both binary and ternary OSC configurations.

Main Methods:

• Synthesis of three nonfused-ring electron acceptors (2TT, 2TT-C6-F, 2TT-C11-F) featuring identical steric hindrance groups.
• Fabrication and characterization of binary and ternary organic solar cells using the synthesized acceptors.
• Analysis of absorption spectra, energy levels, film morphology, and power conversion efficiencies (PCEs).

Main Results:

• 2TT-C11-F demonstrated red-shifted absorption and suitable energy levels, leading to a binary OSC PCE of 13.03%.
• 2TT, when used in a ternary system with D18:BTP-eC9-4F, achieved a remarkable PCE of 19.39% due to complementary absorption and cascade energy levels.
• The performance of the OSCs correlated with the terminal groups and alkyl side chains of the electron acceptors.

Conclusions:

• The designed 2TT-series nonfused-ring electron acceptors show great potential for high-performance OSCs.
• Tailoring electron-withdrawing and lateral alkyl side chains is an effective strategy for optimizing OSC efficiency.
• The study highlights the viability of these materials for both binary and ternary OSC applications.