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 C 60 fullerene with Phenyl-C 61 -butyric-acid-methyl-ester (PCBM) is investigated by means of density functional theory method to elucidate the structures and electronic states of C 60 -PCMB complexes. C 60 -PCBM blends are typically used in solar cell. Studying the electronic structure of C 60 -PCBM is important for elucidating the mechanism of solar cells. The intermolecular distances for C 60 and PCBM dimers were calculated to be 3.70 and 2.34 Å, respectively. In C 60 dimer, the five membered ring of C 60 interacted with the six membered ring of neighbour C 60 . Two hydrogen bonds between side chains of PCBM are connected in the PCBM dimer. The binding energies were 1.4 kcal mol −1 (C 60 dimer) and 2.6 kcal mol −1 (PCBM dimer). In the C 60 -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 C 60 -PCBM complexes and the basis set superposition error were discussed on theoretical results.