Estimation of maximum absorption wavelength of polymethine dyes in visible and near-infrared region based on time-dependent density functional theory

Abstract Polymethine dyes have been utilized in various applications, including optical functional materials. The maximum absorption wavelength ( λ max ) of polymethine dyes is the key for designing optical functional materials. However, there have been few theoretical studies on λ max , especially in the near-infrared region. Therefore, using time-dependent density functional theory (TD-DFT), we calculated the excited states of 70 polymethine dyes with λ max ranging in the visible-to-near infrared region. We also compared these calculated λ max values with experimental ones, using linear regression analysis, and confirmed a strong correlation between the experimental and theoretical λ max values when the portion of the Hartree-Fock exchange in exchange–correlation functionals is relatively high. Linear regression analysis revealed that the experimental λ max values of the polymethine dyes can be quantitatively estimated by combining the TD-DFT calculations with the regression curves. Although several polymethine dyes may exhibit different behaviors at λ max , we could categorize these dyes into a few groups and estimate their excitation energies using regression curves suitable for the respective groups.