Theoretical investigation of the photovoltaic properties of MgSnN$_{2}$ for multi-junction solar cells

Abstract

The orthorhombic crystal structure of the MgSnN$_2$ compound with Pna2$_1$ symmetry has been investigated as a low-cost, non-toxic material for photovoltaic (PV) applications using density functional theory (DFT) and spectroscopic limited maximum efficiency (SLME) calculations. A detailed analysis of the electronic and optical properties was performed using the mBJ semilocal exchange functional. The bandgap of MgSnN$_2$ is found to be 2.45 eV. SLME photovoltaic analysis suggests that a thin film of MgSnN$_2$ with a thickness of 2 $μ$m can reach an efficiency of 13.17% at room temperature. This efficiency was further improved through the simulation of a multi-junction device, where the tandem configuration increased the efficiency from 12.80% (single-junction) to 22.42%. Furthermore, introducing cation disorder can further reduce the bandgap, enhancing its suitability for solar cell applications.

Figures (9)

• Figure 1: Standard view (left panel) and top view (right panel) of cation-ordered wurtzite-type of MgSnN$_{2}$ compound with $Pna2_{1}$ space group.
• Figure 2: The electronic band structure of MgSnN$_{2}$ along high symmetry direction of the Brillouin zone (presented in inset). Results obtained from the mBJ method.
• Figure 3: (a) Total densities of states (TDOS) and (b) partial densities of states (PDOS) of MgSnN$_{2}$.
• Figure 4: Dielectric function of the MgSnN$_{2}$ compound as a function of energy for the means diagonal components of the dielectric tensor: (a) real part, $\epsilon{1}(\omega)$, and (b) imaginary part, $\epsilon_{2}(\omega)$.
• Figure 5: (a) The absorption coefficient $\alpha(\omega)$, (b) the refractive index n($\omega$) and (c) the optical reflectivity r($\omega$) of MgSnN$_{2}$ compound as a function of energy for the means diagonal components.