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

Abstract

Explorations of stable lead-free perovskites have currently achieved substantial interest to overcome the instability and avoid toxicity related issue faced with the lead-based perovskites. In this study, we have comprehensively studied the stability, nature and origin of electronic, transport and optical properties of inorganic halide double perovskites, which could provide a better understanding of their possible potential applications. The density functional theory is used to investigate the different physical properties of these materials. The stability of these cubic materials is validated by optimizing the structure, tolerance factor, mechanical stability test. The materials are small band gap semiconductors with outshining optoelectronic performance. Due to high optical absorption, high conductivity and low reflectivity they have great potential to be used for optoelectronic application purpose. Because of small band gap we have also investigated the variation of various transport parameters with chemical potential. The semiconducting nature of materials results in ZT close to unity predicting its excellent application in thermoelectric technology.

First‐principles investigation of Rb2Ag(Ga/In)Br6 for thermoelectric and photovoltaic applications

“…In addition, they have excellent optoelectronic properties such as high optical absorption, appreciable optical conductivity, large dielectric constant, and long carrier lifetime. To date, many lead‐free double halide perovskites have been explored for energy applications [13–17]. But, most of them are either not stable or do not have suitable electronic and optical properties.…”

First‐principles investigation of structural, optoelectronic, and thermoelectric properties of Cs 2 Tl(As/Sb)I 6

“…In addition to this, many other lead-free double halide perovskites have also been explored. [35][36][37][38] But, the explored lead-free double halide perovskites are either not stable or not having suitable electronic and optical properties. In this regard, exploration of new lead-free double halide perovskites is urgent.…”

“…Only very few experimental studies were performed to investigate their thermoelectric properties, but interest toward the thermoelectric response is now increasing. 38 Motivated by small band gap values of Cs 2 Tl(As/Sb)I 6 , we have investigated their thermoelectric properties. We have obtained the higher figure of merit values from Cs 2 Tl(As/Sb)I 6 due to their ultra-low thermal conductivity and high electrical conductivity.…”

“…However, the band gap values of Cs 2 SnCl 6 and Cs 2 AgInCl 6 are above 2.0 eV which leads to poor photovoltaic performance. In addition to this, many other lead‐free double halide perovskites have also been explored 35‐38 . But, the explored lead‐free double halide perovskites are either not stable or not having suitable electronic and optical properties.…”

“…Instead of low thermal conductivity arising from the occupation of cations in the octahedral structure, it is very surprising that these perovskite halides are mostly studied for optoelectronic applications. Only very few experimental studies were performed to investigate their thermoelectric properties, but interest toward the thermoelectric response is now increasing 38 . Motivated by small band gap values of Cs 2 Tl(As/Sb)I 6 , we have investigated their thermoelectric properties.…”