Effect of NH2 Substituent Group on PC61BM Properties Using DFT

The effects of the substituents and substituent positions on the structure, electronic and spectral properties of the phenyl-C 61 -butyric-acid-methyl-ester (PC 61 BM) using Density functional theory (DFT) and time-dependent density functional theory (TD-DFT), with hybrid functional B3LYP and 6-31G(p,d) basis sets. The results show that the values of bonds length and angles have a good agreement with previous studies. The Koopman's method which is used to calculate some important electronic variables, such as the ionization energy, electron affinity, electronegativity, and energy gap. Also, the results showed that the location of addition subgroup on the PC 61 BM molecule effect on the characteristics studied. The addition of the NH 2 caused a redshift to the visible spectrum due to reduces the energy gap that means construct new molecular electronic structures which can be used in applications of the organic solar cells.