Theoretical Design of Photofunctional Molecular Aggregates for Optical Properties: An Inverse Design Approach

Properties of molecular aggregates are defined by their composition and structure. It is becoming possible to control these elements via advances in experimental techniques, and therefore the design guidelines are demanded for developing efficient optical materials. Here we propose a theoretical design approach for photofunctional molecular aggregates using an inverse design framework, the linear combination of atomic potentials (LCAP). The Frenkel exciton model coupled with the LCAP is introduced for designing systems with desired optical properties by gradient-guided optimization searches in terms of constituent molecules in the chemical space of molecular aggregates. We have applied this approach to design one-dimensional molecular aggregates having locally maximized absorption and/or circular dichroism (CD) intensities as an example. By exploring a small fraction of the vast chemical space of 10(26) possible systems varying in composition and structure, we successfully obtained the optimal aggregates. The optimal structure-photofunction relationships were investigated from the designed systems. We clarified that the maximum CD of the designed system is nonlinearly enhanced depending on the number of constituent molecules. Furthermore, we analyzed the optical spectra and revealed that the potential of the photofunctions is sufficiently exploited. The present method is useful to design photofunctional molecular aggregates and accelerate optical material discoveries.