Small‐band gap halide double perovskite for optoelectronic properties

Abstract

The long-term instability and the existence of toxic lead have hindered the commercialization of photovoltaic devices. Perovskites offer a multitude of crystallographic configurations and substituents that portend the promise of enhanced device performance, while resolving concerns of stability and toxicity. During past few years, lead free perovskites have emerged the most promising photovoltaic materials. Herein, we reported new lead-free organic perovskites by first principle calculation with possible application in optoelectronic and spintronic devices. The new halide double perovskites Cs 2 GeVX 6 (X = Cl, Br, I) has a smallest band gap ranging from 2 to 3 eV suitable for optoelectronic application in visible as well as UV region. Band profile reveals semiconducting nature of these materials with high values of magnetic moment. Stability of these alloys is determined by calculating the elastic constants. These materials owe brilliant intrinsic properties because of large number of nearest neighboring magnetic ions and strong coupling between various d, s, p orbitals. Our finding will pave a way for future experimentalists for designing and tuning of new-type Pb-free halide perovskite for optoelectronic application.

New Lead Free Halide Double Perovskite Materials: Potential Substitutes Towards Green Technology and Stable Optoelectronic Application

“…The elastic constants and thereby mechanical behavior of these considered double halide perovskites are predicted with the help of the Cubic Elastic package [42]. [43] for elastic constants to be followed.…”

“…The cubic structure would be mechanically stable only if the deformed structures are at higher energy compared to the cubic phase. This leads to a limiting condition 11 − 12 > 0, 11 > 0, 44 > 0, 11 + 2 12 > 0, 12 < < 11 [43] for elastic constants to be followed.…”

Potential lead-free small band gap halide double perovskites Cs2CuMCl6 (M = Sb, Bi) for green technology

“…The cubic structure would be mechanically stable only if the deformed structures are at higher energy compared to the cubic phase. This leads to a limiting condition 39 for elastic constants to be followed where C 11 longitudinal elastic constant indicates elasticity along the axis of unit cell and C 12 and C 44 are shear elastic constants define elasticity in shape.…”

Theoretical investigation of octahedral tilting and bandgap non‐linearity in monolayer Ruddlesden‐Popper A 2 Pb 1‐x Ge x I 4 perovskites

“…27 In a recent study of Ge-Sn-based perovskites, by increasing the Ge concentration, the structural stability was increased, and bandgap was tuned from 1.8 to 2.5 eV, and oxidation of both Sn and Ge was reduced. 28 Ge-based solar absorber as X 2 GeI 6 (X = K, Rb, Cs), 29 Cs 2 GeVX 6 (X = Cl, Br, I), 30 and CsGeX 3 (X = F, Cl and Br) 31 offers small-bandgaps with promising optoelectronic properties. Additionally, Ge-based Cu 2 ZnSn 1Àx Ge x S 4 can be used as a hole transporting layer, 32 thus upgrading the performance of leadfree perovskite solar cells.…”