Understanding the Role of Spacers in Modulating Nonlinear Optical Properties of Triphenylamine Derivative Chromophores: A Computational Approach

This study investigates the second-order nonlinear optical (NLO) properties of three novel triphenylamine derivative chromophores: 2,2'-((5-((E)-4-((E)-4-(diphenylamino) styryl) styryl)-1,3-phenylene) bis(methanylylidene)) dimalononitrile abbreviated as S1; 2,2'-((5-((E)-2-(5-((E)-4-(diphenylamino) styryl) furan-2-yl) vinyl)-1,3-phenylene) bis(methanylylidene)) dimalononitrile referred to as S2; and 2,2'-((5-((E)-2-(5-((E)-4-(diphenylamino) styryl)-1H-pyrrol-2-yl) vinyl)-1,3-phenylene) bis(methanylylidene)) dimalononitrile, abbreviated as S3, utilizing density functional theory and time-dependent density functional theory. The study focuses mainly on the impact of two π-spacers, namely furan and pyrrole on the second-order NLO properties of these chromophores. The computational analysis reveals that the pyrrole-substituted chromophore S3 exhibits superior NLO properties, with a dipole moment of 3.78 Debye, linear polarizability of 97.23 × 10-24 esu, and first hyperpolarizability of 189455 × 10-33 esu. These findings highlight the significance of molecular design in enhancing NLO responses, demonstrating that incorporating strong electron-donating, withdrawing groups, and appropriate π-spacers can improve optical properties. This research contributes to the development of organic NLO materials essential for various photonic applications, including optical communication and other potential uses.