Exploring the molecular spectroscopic and electronic characterization of nanocrystalline Metal-free phthalocyanine: a DFT investigation

Abstract

The molecular structure optimization and harmonic vibrational frequencies of nanocrystalline metal-free phthalocyanine were investigated using the density functional theory (DFT) implemented in the Gaussian 09 program through B3LYP/6-311G basis set. Thermodynamic and non-linear optical (NLO) characteristics, total dipole moment, HOMO–LUMO energies, natural population analysis (NPA), and global chemical reactivity descriptors were examined. TD-DFT evaluations were used to interpret the electronic absorption. The experimental results and computed values match up adequately. An essential component of photovoltaic devices and the optimized HOMO–LUMO energy gap (2.16 eV) were estimated and compared with those obtained experimentally. The energy band model was used to check the probability of the transition type and estimate the values of energy gaps, which were found to be indirectly allowed. To provide a comprehensive picture for the characterization and determine the activation energy of the charge carriers, the DC electrical conductivity was also examined. It was revealed to have a value between 0.767 and 1.288 eV depending on the temperature range.