COMPUTER SIMULATION OF π – π INTERACTIONS OF TETRATHIOPHENE MOLECULES

Abstract

The properties of the supramolecular organization of conjugated polymers strongly affect the mobility of charge carriers and, consequently, the properties of produced electronic devices based on them. Therefore, it is important to learn how to build computational models capable of reproducing the structure of such polymers with the highest possible accuracy. One of the main driving forces of the self-assembly of supramolecular structures in conjugated polymers is π – π interaction. Taking it into account is a rather difficult task, especially when constructing mesoscale models. In this work, we use the electron density functional theory to develop a methodology for calculating conjugated polymers taking into account π – π interaction. The geometric characteristics of stacks of four tetra thiophene molecules were studied. The performed calculations show that the use of the M06-2X-D3 functional makes it possible to correctly model the interactions of oligothiophene molecules and the structure of the resulting aggregates, while semiempirical calculations by the PM7 method of conjugated polymers are suitable only for rapid preliminary optimization of models. The tested calculation technique is of great importance for the parametrization of mesoscale modeling schemes.

Keywords

• organic solar cells
• organic polymers
• thiophenes
• quantum chemical calculations
• π – π stacking interaction