Estudo dos efeitos de solventes nas propriedades ópticas não lineares em derivados de Azo-Carbazole.

Abstract

Organic materials based on azo-carbazole derivatives have attracted significant interest in photonic and optoelectronic applications due to their push–pull character. This work presents a theoretical study of seven azo-carbazole compounds, employing Density Functional Theory (DFT), its time-dependent extension (TDDFT), and the Polarizable Continuum Model (PCM). The aim is to evaluate how the solvent medium influences their geometric and nonlinear optical (NLO) properties. Ground- and excited-state dipole moments, absorption spectra, first hyperpolarizabilities (βHRS), and depolarization ratios were computed using long-range corrected hybrid functionals. The results indicate a clear distinction between the substituents: electron-donating groups induce local polarization but result in modest βHRS values and nearly isotropic behavior. In contrast, strong acceptor groups stabilize charge-transfer states, significantly increasing the dipole-moment variation (Δμ) and enhancing the nonlinear response βHRS. It was also observed that solvation in polar media amplifies these trends, causing bathochromic shifts in the absorption spectra and increments in the NLO response exceeding 200% in some cases. The analysis performed using the two-state model confirms a strong correlation between Δμ and hyperpolarizability, establishing important guidelines for the rational design of efficient organic chromophores for photonics.