New design strategy for the two-photon active material based on push-pull substituted bisanthene molecule.

Area of Science:

• Computational Chemistry
• Materials Science
• Organic Electronics

Background:

• Bisanthene molecules with donor-acceptor substituents are investigated for their optical properties.
• Mimicking graphene nanoribbons, these molecules show potential in advanced materials.
• Understanding two-photon absorption is crucial for applications like optical switching and bio-imaging.

Purpose of the Study:

• To investigate the origin of strong two-photon transition probability in donor-acceptor substituted bisanthene molecules.
• To compare the two-photon absorption properties of bisanthene with single versus multiple donor-acceptor pairs.
• To elucidate the relationship between molecular structure, electronic asymmetry, and two-photon absorption.

Main Methods:

• Time-dependent density functional theory (TD-DFT) was employed for calculations.
• Linear and quadratic response theories were used to evaluate one- and two-photon absorption parameters.
• The long-range corrected CAMB3LYP functional was utilized for accurate electronic structure calculations.

Main Results:

• Bisanthene molecules with a single donor-acceptor pair exhibit higher two-photon transition probability compared to those with three pairs.
• This observation holds true for various donor (-OMe, -NH2) and acceptor (-NO2) combinations.
• Molecular design, specifically the positioning of donor-acceptor moieties, significantly influences electronic asymmetry.

Conclusions:

• Strategic placement of donor-acceptor groups in bisanthene molecules can tune two-photon absorption properties.
• Enhanced ground and excited state dipole moment differences, arising from electronic asymmetry, are key to high two-photon transition probability.
• These findings provide insights for designing novel materials with tailored optical responses for photonic applications.