Polyaromatic Systems Combining Increasing Optical Gaps and Amplified Nonlinear Optical Properties. A Comprehensive Theoretical Study on B3N3 Doped Nanographenes

Materials combining amplified nonlinear optical responses and wide optical gaps that ensure high laser-induced damage thresholds and broadband transparency are highly required for photonic applications. In this article, we use well-established quantum chemical methods to demonstrate that a special class of polyaromatic hydrocarbons, in which multiple borazine (B3N3) units substitute aromatic carbon sextets, are suitable for the design and synthesis of systems meeting both above requirements. Computations conducted in a wide assortment of purposely designed nanographene model systems exposed robust doping/property relations which point out that multiple B3N3 doping can be considered as an efficient strategy to enhance the quadratic nonlinear optical responses of a given polyaromatic hydrocarbon maintaining at the same time wide optical gaps. A detailed analysis of the underlying charge transfer mechanism revealed that the observed features stem from local in character electronic excitations occurring between the incorporated B3N3 units and neighboring aromatic sextets.