Electronic Properties of Nanomaterials: A Quantum Mechanical Perspective

Electronic Properties of Nanomaterials: A Quantum Mechanical Perspective

Due to huge vastness of size, shape, chemical composition at nanoscale materials number of materials available for computational studies increases. The study of static and dynamic electron-electron correlations and band gaps makes it possible to study the electronic properties of Nano-materials. These properties are extremely sensitive to doping, impurities and change in electronic configuration. The fundamental problem at this scale is to achieve the ultimate computational performance can cost reduction.

Various theories can be used to study electronic properties of material including density function theory (DFT) and density functional tight binding method (DFTB). These methods could be used to study both types of properties; ground state properties like band structure and molecular orbitals along with excited state properties like transfer change and absorption spectra.

Core electronic properties of porphyrin and phosphorene nanotubes have been analyzed as function of their size along with the effects of nitrogen doping on graphene nano-flakes. There also has been shown the importance of computational and theoretical methods for synthesis and characterization of methods. Utilizing extensive scale DFT analysis has been shown for the electronic properties of porphyrin nanotubes. It was observed that band gap of these materials has fluctuations with change in size. These fluctuations depend upon aromatic and nonaromatic characteristics of porphyrin which are size dependent. The electronic transition is these elements are band gap transitions i.e. optically active states which can easily be observed in photoelectron spectroscopic experiments. In contrast to conventional CNTs in porphyrin both donor-acceptor type of heterojunctions is possible due to its band gap fluctuations.

The large-scale DFT analysis shows that phosphorene nanotubes show a very complicated direct to indirect band gap transition as the function of diameter of the nanotubes. The strain leading to the contracted diameter of phosphorene nanotubes sources a transition from direct to indirect band gap for nanotubes. This provides a wide range of tunability as compared to conventional CNTs and can be used in light emitting diodes and solar cells.

 The effects of nitrogen doping on graphene nanoflakes has also been studies. Several characteristics like molecular orbitals and valance electron excitations can be analyzed by using DFT analysis. Most of the properties of graphene nanoflakes like vertical excitation energies and corresponding absorption spectra are strongly dependent on nanoflake size.