THEORETICAL INVESTIGATION ON ELECTRONIC STRUCTURES AND OPTOELECTRONIC PROPERTIES OF VINYL FUSED MONOMERIC AND OLIGOMERIC BENZIMIDAZOLE DERIVATIVES

Abstract

In the present work, investigation on seven (7) vinyl fused monomeric benzimidazole (VFMBI) and seven (7) vinyl fused oligomeric benzimidazole (VFOBI) derivatives using density functional theory (DFT) and time dependent-density functional theory (TD-DFT) has reported. The effects of electron donor and acceptor groups on the electronic structure such as highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energies, HOMO-LUMO energy gap, ionization potentials (IPs), electro affinities (EAs), internal reorganization energies of holes and electrons (𝜆ℎ/𝑒 ) and excited state properties have explored in the present work. In addition, natural bond orbital (NBO) analysis of these compounds has been investigated to reveal the typical stabilization interactions in these molecules. Hence, the aim of the present work is to explore the electronic structures and optoelectronic properties of the vinyl fused monomeric benzimidazole (VFMBI) and vinyl fused oligomeric benzimidazole (VFOBI)) derivatives on the basis of the DFT quantum mechanical calculations, and to make an idea on the parameters influencing the organic light emitting diode (OLED) efficiency toward a better understanding of the structure–property relationships. Moreover, the calculated results reveal the suitable optoelectronic properties of Benzimidazole oligomer derivatives and the reliability of computational chemistry techniques used. Of the investigated molecules, 4_MABIOCY shows potential optoelectronic properties and can be used as a potential emitter in near infrared NIR-OLED due to absorption and emission in NIR (𝜆𝑚𝑎𝑥/𝑎𝑏𝑠 / 𝜆𝑚𝑎𝑥/𝑒𝑚𝑠 =883 nm/958 nm)region and as a potential electron transport material in OLEDs due to their narrow band gap, high hyperpolarizability, high electro affinity and low 𝜆𝑒

while 10_CYBIOMA and 8_FMBIOMA can be used as a potential blue fluorescent host materials in the development of white OLEDs, due to wide band gap and better optical properties.