Study of electronic and transport properties of melanin structure using Density Functional Theory

Abstract

Organic semiconductors are a relatively new member of the semiconductor family and composed of molecules containing carbon, hydrogen, and another element. Melanin is a pigment that colours skin, eyes and hair and it could soon be facing a new generation of biologically friendly electronic devices in applications such as medical sensor and tissue stimulation treatment. The need to find the correct solvent for the melanin still remains challenged. In this work the electronic properties of eumelanin was studied under gas phase and solution, using Integral Equation Formalism Polarizable Continuum Model (IEFPCM) using different solvent. Total energy, Homo-Lumo energy gaps and density of states were reported. Gaussian09 code which uses density functional theory as the working principle was used to study the electronic and transport properties of melanin structure. Three exchange functional: HF (HF), GGA (PBE) and Hybrid (B3LYP) were used at different basis set of 3-21G, 6-31G, and 6-311G. It was found that at the 6-311G level for the three exchange functional, the total energy of -2981.03028, -2996.839821 and -3000.227297 eV respectively. However, HOMO-LUMO energy gap in gas phase was improved to be 2.65 eV and 2.79 eV, 2.65 eV in DMSO and Acetonitrile respectively. It was concluded that DMSO solvent is more efficient for melanin compound. However, it is recommended to increase the level of approximation.