Monolayer materials are promising material in applications, such as possess some layers with sturdy in-plane bonds. These materials represents two-dimensional (2D) materials which are possess a vertical weak Van der Waals (VdW) interactions sandwiched among the neighboring sheets. These structures of layers offer the chance to be split to free atomic layers. So new class material with two dimensional transition metal dichalcogenides which includes PtS2 (Se2) have unique geometric structural, electronic and optical properties are studied. It has attracted the attention of many researchers for its extensive applications in (catalysis, sensing, electronics, and optoelectronics devices). It has been disclosed from the outcomes that these monolayers are dynamically stable according to the phonon calculations. Also, the direct band gaps located at K point for MoS2 and MoSe2 are 1.67 eV and 1.484 eV and for PtS2 and PtSe2 located between Γ-M points are 1.887 and 1.66, respectively. Also, the PtS2 have indirect band gap of about 1.775 eV situated at KΓ- ΓM and for PtSe2 is 1.401 eV at Γ- ΓM path. The results show that the maximum absorption coefficients are between 14×104 and 16.4×104 cm-1 for PtS2 and MoSe2, respectively. Besides, the maximum conductivities are between 2.09×101 and 3.65×1015 1/s for PtSe2 and MoS2, and the major values Likewise, the optical properties determined over rang energy 0.30 eV. The work function is equal 6.197eV for PtS2 and 5.628eV for PtSe2. It has been shown by studying photon dispersion of both monolayers that it is stable because it does not contain imaginary frequencies.
Towards the evaluation of defects in MoS2 using cryogenic photoluminescence spectroscopy