Electronic, optical, and thermoelectric properties of perovskite variants A ₂ BX ₆ : Insight and design via first‐principles calculations

Abstract

Summary Lead halide perovskites are considered as a material of choice for solar cell applications. However, there are challenges: organic cations in halide perovskites are unstable, and lead is toxic. To address these issues, we propose and investigate some potential alternatives to lead in the form of A2BX6 perovskites using the first‐principles calculations. Besides simple approximation potentials, we use a highly successful hybrid functional HSE06, to calculate the electronic, optical, and thermoelectric properties of A2PdI6 (A = K, Rb, and Cs). Our calculations show that K2PdI6, Rb2PdI6, and Cs2PdI6, are narrow bandgap semiconductors with bandgap of 0.8, 0.92, and 0.9 eV, respectively. The valence band maximum (VBM) of A2PdI6 is mainly composed of I‐5p orbitals while the conduction band minimum (CBM) is formed of Pd‐4d and I‐5p orbitals. Due to the ideal bandgap and excellent light absorption, Rb2PdI6 stands out as a potential candidate for usability in tandem solar cells. In addition, p‐type doping at a carrier concentration of 1 × 1018 cm−3 makes these perovskites a material of choice for thermoelectric energy applications.

A computational study of double perovskites A2BI6 (A = Cs, K, Rb; B = Pt, Sn) invoking density functional theory

“…In the case of Moss relation, the maximum and minimum refractive index values are found for Cs 2 SnI 6 and K 2 PtI 6 , respectively. The refractive index computed from the Wemple relation is in agreement with the recent study performed by Faizan et al 49 for perovskites materials.…”

“…The geometry and frequency optimization of A 2 BI 6 are performed with the help of the computational software Gaussian‐16 47 . Exchange correlation generalized gradient approximation (GGA) have been successfully applied in the computation of double perovskite materials 17,48–50 . The use of the basis set LANL2DZ has already been reported in the study of perovskite materials 51–53 .…”

Pressure-dependent physical properties of cesium–niobium oxide: a comprehensive study

“…The spin degeneracy of La- and Co-based perovskites was found to improve the effective mass of a single charge carrier, leading to high Seebeck values due to an elevated charge carrier entropy. 28,29 Similarly, other studies have predicted the potential of lead halide perovskites, 30,31 La 1− x Sr x CoO 3 , 32 dual-doped Ca 3 Co 4 O 9 , 33 and hole-doped GeSe materials for thermoelectric energy devices, owing to their high thermoelectric performance. A study on ABO 3 (A = Rb, Cs and B = Nb, Ta) compounds examined their optical, electronic, thermoelectric, and thermodynamic properties at different pressures.…”

Strain effects on electronic, optical properties and carriers mobility of Cs2SnI6 vacancy‐ordered double perovskite: A promising photovoltaic material

“…Recently, halides with a general formula A 2 BX 6 have attracted much attention as new alternative candidates for substituting lead-bearing ABX 3 perovskites [15][16][17][18][19][20][21][22][23][24][25]. In these perovskite derivatives, the B atoms are positioned at the centers of the [BX 6 ] À2 octahedra and the half of the B-sites are unoccupied; therefore, the [BX 6 ] À2 octahedra are isolated in these compounds [26].…”

“…With the aim of overcoming these undesirable properties, scientists have made a lot of attempts to find alternatives for substitution of lead, in particular using replacement of this toxic chemical element by more eco-friendly tin and germanium. Nevertheless, the maximum process cycle efficiency (PCE) of approximately 13% was reported in reference 10 for Sn-based perovskites that is lower than those of Pb-based perovskites, even if they possess suitable band gaps and high absorption coefficients [11][12][13][14].Recently, halides with a general formula A 2 BX 6 have attracted much attention as new alternative candidates for substituting lead-bearing ABX 3 perovskites [15][16][17][18][19][20][21][22][23][24][25]. In these perovskite derivatives, the B atoms are positioned at the centers of the [BX 6 ] À2 octahedra and the half of the B-sites are unoccupied; therefore, the [BX 6 ] À2 octahedra are isolated in these compounds [26].…”