Comparative studies of CHN pyridine and CHNS pyrrole for optoelectronic applications by mBJ approach.

The modified Becke-Johnson exchange (mBJ) potential plus the generalized gradient approximation (GGA) correlation are used for the calculation of the optoelectronic properties of the CHN pyridine and CHNS pyrrole. Electronic band gaps of CHN pyridine and CHNS pyrrole have been determined to be 4.65 eV and 3.41 eV by band structure spectra, respectively. According to the Penn model, there is an inverse relationship between the band gap value and static dielectric constant along the x-direction. The density of states spectra shows that the p state of S atoms plays a key role in the optical spectra. In the refractive index spectra, the nature of materials changes from linear to nonlinear with superluminal nature in a narrow energy range of 3.9-4.7 eV for CHNS and 5-7.7 eV for CHN. Cauchy parameters are calculated and predicted values are extended in the UV (ultraviolet) and visible regions. Obtained plasmon energies are in close agreement with suitable optical materials such as α-AlO making the material more effective to use in new optical devices.