Density functional theory study on the interaction of C60 fullerene with PCBM

Abstract

Functionalized fullerenes are known as high-performance molecules. Herein, the interaction of C60 fullerene with Phenyl-C61-butyric-acid-methyl-ester (PCBM) is investigated by means of density functional theory method to elucidate the structures and electronic states of C60-PCMB complexes. C60-PCBM blends are typically used in solar cell. Studying the electronic structure of C60-PCBM is important for elucidating the mechanism of solar cells. The intermolecular distances for C60 and PCBM dimers were calculated to be 3.70 and 2.34 Å, respectively. In C60 dimer, the five membered ring of C60 interacted with the six membered ring of neighbour C60. Two hydrogen bonds between side chains of PCBM are connected in the PCBM dimer. The binding energies were 1.4 kcal mol−1 (C60 dimer) and 2.6 kcal mol−1 (PCBM dimer). In the C60-PCBM complex, five different structures were found to be stable. The binding energies were distributed in the range 1.6–3.7 kcal mol−1. The electronic states and excitation energies of C60-PCBM complexes and the basis set superposition error were discussed on theoretical results.