New lead‐free double perovskites X ₂ GeI ₆ (X = K, Rb, Cs) for solar cells, and renewable energy as an alternate of hybrid perovskites

Abstract

Summary Recently, the unique double perovskites are continuously being used for solar cells and thermoelectric applications because of stable structures and high energy conversion efficiency. We addressed the optical and transport characteristics of X2GeI6 (X = K, Rb, Cs) by first‐principle calculations. The tolerance factor confirms the structural stability. The computed band gaps 1.27 eV (K2GeI6), 1.24 eV (Rb2GeI6), and 1.13 eV (Cs2GeI6) plunge the maximum absorption in visible light zone. The first absorption bands 459 to 826 nm for K2GeI6, 477 to 885 nm for Rb2GeI6, and 653 to 992 nm for Cs2GeI6 are outstanding for visible light solar cells. While the second absorption bands are for other optoelectronic devices like surgical equipment. The optical characteristics are debated by frequency‐dependent dielectric constants (ε1, ε2), refractive index, and absorption coefficient. Thermoelectric performance is evaluated by large values of power factor and ultralow values of thermal conductivity for both n‐ and p‐type of charge carriers. Highlights An alternative of organic‐inorganic and Pb based perovskites Ideal band gaps 1.27 eV, 1.24 eV, and 1.13 eV of K2GeI6, Rb2GeI6, and Cs2GeI6 for solar cells Absorption in the visible region increases their potential for solar cells. Observation of ultralow lattice thermal conductivity.

Electronic and optical properties of lead‐free double perovskites A2BCl6 (A = Rb, Cs; B = Si, Ge, Sn) for solar cell applications: A systematic computational study

“…Mahmood et al [ 22 ] investigated perovskites material Rb 2 Pd(Cl/Br) 6 by using the DFT approach and found that the energy gap of the system is reduced from 1.88 to 1.21 eV when Cl is replaced by Br anion. Al‐Muhimeed et al [ 23 ] investigated X 2 GeI 6 (X = K, Rb, Cs) by using a computational technique. They reported the band gap of K 2 GeI 6 , Rb 2 GeI 6 , and Cs 2 GeI 6 as 1.27, 1.24, and 1.13 eV, respectively.…”

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

“…Rb 2 PdI 6 , with an energy gap of 0.92 eV and high optical absorption, is reported as a suitable material for photovoltaic devices. Al‐Muhimeed et al 30 studied X 2 GeI 6 (X = K, Rb, Cs) by using the DFT approach. They reported that the band gap, optical characteristics, and tolerance factor of these materials are in a suitable range and can be utilized for photovoltaic devices.…”

First principles investigation of halide based Rb2NaGaZ6 (Z = Br, I) double perovskites for energy harvesting applications

“…7,8 The extensive interest of researchers in double perovskites has grown over the last few years due to their conceivable implementation in renewable energy. 13,14 By using these perovskites the ongoing record power conversion efficiency reaches up to 25.7%. 15…”

“…7,8 The extensive interest of researchers in double perovskites has grown over the last few years due to their conceivable implementation in renewable energy. 13,14 By using these perovskites the ongoing record power conversion efficiency reaches up to 25.7%. 15 For analyzing the most competent, reliable, and harmless substitutes, the double perovskites based on halide (X) (generally named as A 2 BB ′ X 6 ) have been searched.…”