From Data to Dimers: Engineering Acene Derivatives for Photovoltaic Singlet Fission

Area of Science:

• Photophysical processes
• Materials science
• Renewable energy

Background:

• Singlet fission (SF) is a promising photophysical process for enhancing solar cell efficiency by minimizing thermal energy loss.
• Acenes are key chromophores for SF, but their dimers face challenges like poor stability and low triplet energies, limiting device applications.
• Higher triplet energies and improved stability are crucial for acene dimers to act as effective triplet sensitizers in hybrid solar cells.

Purpose of the Study:

• To design and identify acene dimers with efficient singlet fission (SF) capabilities.
• To develop materials with enhanced kinetic stability and higher triplet energies for photovoltaic applications.
• To create suitable triplet sensitizers for hybrid solar cell architectures.

Main Methods:

• A combinatorial assembly strategy was used to create a library of over 15,000 acene derivatives.
• Transformer-based machine learning models were employed for high-throughput virtual screening of energetic properties.
• A protocol was developed to approximate acene dimer energetics from monomer data for efficient screening.

Main Results:

• Numerous promising acene dimer candidates were identified for experimental synthesis and evaluation.
• The study identified a key design principle: incorporating (benzo)furan and (benzo)thiophene units into 5- and 6-ring heteroacenes.
• This incorporation systematically tunes energetics towards the SF regime while maintaining high triplet energies.

Conclusions:

• The designed acene dimers show potential for efficient singlet fission and improved stability in photovoltaic devices.
• The findings provide a pathway for developing next-generation materials for high-efficiency solar cells.
• Incorporating heteroaromatic units offers a viable strategy for tuning the photophysical properties of acene dimers for solar energy applications.