DFT Study of Polythiophene Energy Band Gap and Substitution Effects

• Main Authors: Si. Mohamed Bouzzine, Guillermo Salgado-Morán, Mohamed Hamidi, Mohammed Bouachrine, Alison Geraldo Pacheco, Daniel Glossman-Mitnik
• Format: Article
• Language: English
• Published: Hindawi Limited 2015-01-01
• Series: Journal of Chemistry
• Online Access: http://dx.doi.org/10.1155/2015/296386
• ISSN: 2090-9063; 2090-9071

Polythiophene (PTh) and its derivatives are polymer-based materials with a π-conjugation framework. PTh is a useful photoelectric material and can be used in organic semiconductor devices, such as PLED, OLED, and solar cells. Their properties are based on molecular structure; the derivatives contain different substitutes in the 3 and 5 positions, such as electron-donating or electron-withdrawing groups. All molecular geometries were optimized at B3LYP/6-31G(d,p) level of theory. The energy gap (Egap) between the HOMO and LUMO levels is related to the π-conjugation in the PTh polymer backbone. In this study, the DFT calculations were performed for the nonsubstituted and 3,5-substituted variants to investigate the stability geometries and electrical properties. The theoretical calculations show that the substituted forms are stable, have low Egap, and are in good agreement with the experimental observations.