Styrene monomer as potential material for design of new optoelectronic and nonlinear optical polymers: density functional theory study

Abstract

Using density functional theory, we have studied the intrinsic properties of styrene. First, we determine the optimized structures, structural parameters and thermodynamic properties to make our simulations more realistic to experimental results and check the stability. Second, we investigate optoelectronic, electronic and global descriptors, transport properties of holes and electrons, natural bond orbital analysis, absorption and fluorescence properties. Finally, we study nonlinear optical (NLO) properties: first- and second-order hyperpolarizability, second and third-order optical susceptibilities, hyper-Rayleigh scattering hyperpolarizability, electro-optical Pockel effect, direct current Kerr effects and quadratic refractive index. The bandgap energy <i>E</i> _g = 5.146 eV and dielectric constant <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub><mml:mrow><mml:mi>ε</mml:mi></mml:mrow> <mml:mrow><mml:mi>r</mml:mi></mml:mrow> </mml:msub> <mml:mo>=</mml:mo> <mml:mn>3.062</mml:mn></mml:math> show that styrene is a good insulator with an average electric field value of 4.43 × 10⁸ Vm^-1. Thermodynamic findings show that our molecule is thermodynamically and chemically stable. Electron and hole reorganization energies of 0.393 and 0.295 eV, respectively, show that styrene is more favourable to hole transport than electron transport. Styrene is transparent with linear refractive index <i>n</i> = 1.750 and quadratic <i>n</i> ₂ = 1.748 × 10^-20 m² W^-1. At the NLO, styrene has a non-zero value of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub><mml:mrow><mml:mi>β</mml:mi></mml:mrow> <mml:mrow><mml:mi>H</mml:mi> <mml:mi>R</mml:mi> <mml:mi>S</mml:mi></mml:mrow> </mml:msub> <mml:mi></mml:mi> <mml:mo>,</mml:mo></mml:math> which confirms the existence of first-order NLO activity. Globally the study shows that the styrene monomer is suitable for the architecture design of new polymer materials for NLO applications and optoelectronic by functionalization.