Boron-Substituted Coronene: Intriguing Geometric and Electronic Properties, and Large Nonlinear Optical Response

Area of Science:

• Materials Science
• Quantum Chemistry
• Condensed Matter Physics

Background:

• Graphene quantum dots (GQDs) are promising nanomaterials with tunable electronic and optical properties.
• Understanding substituent effects is crucial for designing advanced GQD-based materials.
• Coronene serves as a model system for investigating GQD properties.

Purpose of the Study:

• To investigate the impact of boron substitution on the geometric and electronic structure of a coronene-based GQD model.
• To explore the influence of boron substitution on the nonlinear optical (NLO) response of the GQD.
• To assess the potential for tuning magnetic properties (antiferromagnetic/ferromagnetic) via boron substitution.

Main Methods:

• Theoretical investigation using computational chemistry methods.
• Systematic analysis of geometric and electronic structure modifications.
• Calculation of nonlinear optical properties, specifically first hyperpolarizability.
• Evaluation of energy differences between singlet and triplet states.

Main Results:

• Boron substitution induces a noncentrosymmetric apophysis structure in the coronene model.
• A small energy difference (2.5 kcal/mol) between singlet and triplet states allows easy switching between antiferromagnetic and ferromagnetic states.
• The boron-substituted coronene exhibits a large first hyperpolarizability (36241 au) due to a raised structure and intermediate singlet diradical character.
• Boron substitution significantly impacts the electronic structure and NLO response.

Conclusions:

• Boron substitution offers a viable strategy to engineer GQD properties.
• The tunable magnetic and enhanced NLO properties of boron-substituted coronene suggest potential applications in spintronics and nonlinear optics.
• This study provides fundamental insights into the effects of boron incorporation in graphene-based nanostructures.