Abstract:
The growing use of nonlinear optical (NLO) materials in various fields has generated
interest in designing innovative smart NLO materials. This study focuses on three specific
ionic liquids, where the same cation, 1-ethyl-3-methyl imidazolium, is combined with three
different anions (Br-, C-, F-). The study explores the effects of External Electric Field
(EEFs) on these three ILs using Density Functional Theory (DFT) calculations.
The interaction energies calculated confirm the stability of the newly designed ILs.
Applying external electric field (EEFs) ranging from 0.001 a.u to 0.006 a.u leads to a
significant reduction in the E(H–L) gap, and the lowest energy gap of 4.43 eV is observed in
EMIBr at field strength of 0.006 a.u. Natural Bond Orbital (NBO) analysis validates
substantial charge transfer from cations to anions, with the highest transfer observed in
EMIBr. External Electric field enhances the first hyperpolarizability, and EMIBr exhibits
the highest value i.e 1828 a.u at 0.006 a.u. TD-DFT calculations are executed to derive
electronic states influenced by an external electric field (EEF), and the highest λmax (nm)
i.e. 227 nm, is observed in the case of EMIBr at 0.006 a.u. The study also determines
frequency-dependent Second Harmonic Generation (SHG) and Electric-Optical Pockels
Effect (EOPE), with noteworthy values observed i.e 2.0×103 and 9.8×103 respectively in
case of EMIBr. In conclusion, the study provides guidelines for computationally designing
efficient and thermodynamically stable complexes for optical and optoelectronic
technologies. The proposed ILs could find potential applications in new electronic devices,
contributing to the development of advanced NLO materials.
