Endohedral terthiophene in zigzag carbon nanotubes: Density functional calculations

TL;DR

This study uses density functional calculations to explore how terthiophene molecules can be encapsulated inside zigzag carbon nanotubes, revealing stability conditions and electronic properties relevant for optoelectronic applications.

Contribution

It provides the first detailed computational analysis of T3 molecule encapsulation in zigzag CNTs, highlighting stability and electronic effects without hybridization.

Findings

T3 encapsulation is exothermic for CNTs with diameters > 9.5 Å.

Maximum energy gain of 2 eV observed for optimal CNT diameters.

T3 preserves its electronic structure inside CNTs, affecting optical properties.

Abstract

The inclusion and encapsulation of terthiophene (T3) molecules inside zigzag single-walled carbon nanotubes (CNTs) is addressed by density functional calculations. We consider the T3 molecule inside five semiconducting CNTs with diameters ranging from 9.6 to 12.7 Ang. Our results show that the T3 inclusion process is exothermic for CNTs with diameters larger than 9.5 Ang. The highest energy gain is found to be of 2 eV, decreasing as the CNT diameter increases. This notable effect of stabilization is attributed to the positively charged CNT inner space, as induced by its curvature, which is able to accommodate the neutral T3 molecule. The band structure of the T3@CNT system shows that T3 preserves its electronic identity inside the CNTs, superimposing their molecular orbitals onto the empty CNT band structure without hybridization. Our results predict that the electronic states added by the T3 molecules would give rise to optical effects and nonradiative relaxation from excited states.