arXiv subjects

Dibyajyoti Saikia

Publications and source records attributed to Dibyajyoti Saikia.

4 recordsLinked to original sources

arXiv2024

A systematic Investigation of Thermoelectric Properties of Monolayers of ZrX2N4(X = Si, Ge)

In the past decade, it has been demonstrated that monolayers of metal dichalcogenides are well-suited for thermoelectric applications. ZrX2N4 (X = Si, Ge) is a reasonable choice for thermoelectric applications when considering a favorable value of the figure of merit in two-dimensional (2D) layered materials. In this study, we examined the thermoelectric characteristics of the two-dimensional monolayer of ZrX2N4 (where X can be either Si or Ge) using a combination of Density Functional Theory (DFT) and the Boltzmann Transport Equation (BTE). A thermoelectric figure of merit (ZT) of 0.90 was achieved at a temperature of 900 K for p-type ZrGe2N4, while a ZT of 0.83 was reported for n-type ZrGe2N4 at the same temperature. In addition, the ZrGe2N4 material exhibited a thermoelectric figure of merit (ZT) of around 0.7 at room temperature for the p-type. Conversely, the ZrSi2N4 exhibited a relatively lower thermoelectric figure of merit (ZT) at ambient temperature. At higher temperatures, the ZT value experiences a substantial increase, reaching 0.89 and 0.82 for p-type and n-type materials, respectively, at 900 K. Through our analysis of the electronic band structure, we have determined that ZrSi2N4 and ZrGe2N4 exhibit indirect bandgaps (BG) of 2.74 eV and 2.66 eV, respectively, as per the Heyd-Scuseria-Ernzerhof (HSE) approximation.

cond-mat.mtrl-sci↗

arXiv2024

A Comparison of Electronic, Dielectric, and Thermoelectric Properties of Monolayer of HfX2N4(X = Si, Ge) through First-Principles Calculations

The newly emerged two-dimensional (2D) materials family of MSi2N4, where M is a transition metal atom (i.e., Mo, W, etc.), has the potential to be named after the conventional and very popular transition metal di-chalcogenides (TMDC), which got their reputation for having bandgap tunability and high mobility. The HfSi2N4 and HfGe2N4 2D materials are members of the MSi2N4 family and possess very good figure of merit (ZT) and have high mobility, proving their suitability for thermoelectric applications. The HfSi2N4 and HfGe2N4 showed considerable ZT of 0.90 and 0.89, respectively, for p-type and 0.83 and 0.79 for n-type, at 900 K along with high mobility according to the solutions obtained after solving the Boltzmann Transport Equation (BTE). The HfGe2N4 also showed a ZT of 0.84 at 600 K and 0.68 at 300 K, which is also excellent for low-temperature operation. The bandgaps (BG) obtained for HfSi2N4 and HfGe2N4 according to the Heyd-Scuseria-Ernzerhof (HSE) approximation were 2.89 eV and 2.75 eV. The first absorption peak showed in the blue region of the visible spectrum; from this, their usefulness in visible range photodetectors can also be inferred.

cond-mat.mtrl-sci↗

arXiv2023

Low-Temperature Thermoelectric Performance and Optoelectronic Properties of Monolayer of WX2N4(X = Si, Ge)

We investigated the thermoelectric properties of the 2D monolayer of WX2N4 using Density Functional Theory combined with Boltzmann Transport Equation. We obtained an outstanding thermoelectric figure of merit of 0.91 at 400K for p-type WGe2N4, whether it showed a ZT value of 0.56 for n-type at the same temperature. On the other hand, the WSi2N4 showed significantly low ZT at room temperature.

cond-mat.mtrl-sci↗

arXiv2022

A First-principles study on ABBr3 (A = Cs, Rb, K, Na; B = Ge, Sn) halide perovskites for photovoltaic applications

In recent years, halide perovskite-based solar cells have received intensive attention, and demonstrated power conversion efficiency as high as 25.8%. With regard to the toxicity of Pb and the instability of organic elements, all inorganic lead-free perovskites (ILPs) have been extensively studied to achieve comparable or greater photovoltaic performance. In order to develop ILPs as an alternative for solar cell applications, we performed first-principles calculations of ABBr3 perovskites (A = Cs, Rb, K, and Na, and B = Sn, and Ge). Structural, electronic, and optical properties were systematically studied to probe the potentiality in photovoltaic applications. All these ILPs exhibited a direct bandgap in the range of 1.10 to 1.97 eV, highly beneficial for absorbing solar energy. Furthermore, these ILPs demonstrated significant optical absorption (over 105 cm-1) in the whole UV-Vis spectrum. These results will be helpful for designing highly efficient lead-free perovskite solar cells.

cond-mat.mtrl-sci↗