Pis’ma v ZhETF, vol. 112, iss. 6, pp. 387 - 387

Lead-free semiconductors with high absorption:

insight into the optical properties of K₂GeSnBr₆ and K₂GeSnI₆

halide double perovskites

M. Houari⁺¹⁾, B. Bouadjemi⁺, A. Abbad⁺, T. Lantri⁺, S. Haid⁺, W. Benstaali⁺, M. Matougui⁺, S. Bentata^+∗

⁺Laboratory of Technology and of Solids Properties, Abdel Hamid IbnBadis University, 27000 Mostaganem, Algeria

^∗Laboratory of Quantum Physics of Matter and Mathematical Modeling (LPQ3M), Mustapha Stambouli University of Mascara,

29000 Mascara, Algeria

Submitted 21 August 2020

Resubmitted 26 August 2020

Accepted 26 August 2020

DOI: 10.31857/S1234567820180081

In this study, using the first-principles calculations, we have applied the full potential linearized augmented

plane wave (FP-LAPW) method based on density functional theory (DFT) implemented in the code wien2k to

study structural, electronic and optical properties of two halide double perovskites: K₂GeSnBr₆ and K₂GeSnI₆.

The approximations used are generalized gradient approximation (GGA) and for exchange and correlation poten-

tial, we have applied a modified version of the potential proposed by Becke-Johnson (mBJ) to our compounds in

order to improve the bandgaps and approach them to the experimental results.

Structural properties show that these two compounds are cubic and that they crystallize in the space group

(Fm-3m, # 225), they also present a NM phase (non magnetic phase) which has the lowest energy compared to

ferromagnetic and antiferromagnetic phases. The study of electronic properties is divided in two parts: the first one

is for the band structure. The results show that these two compounds present a semiconductor behavior with direct

band gap. The second one is for total and partial density of States. Results presented here confirm the semiconduc-

tor behavior observed in the band structure with a high impact of s-orbital of Sn and p-orbital of Br for valence

band, while for conduction band there is a predominance of hybridization between p-orbital of Sn and p-orbital of

metalloids used.

The most important parameter for optical properties is the dielectric function which has real and imaginary

parts. The results obtained show that these compounds are suitable for storing sun light due to high values of

absorption coefficient and that they are also reflective in optical devices.

Full text of the paper is published in JETP Letters journal. DOI: 10.1134/S0021364020180010

¹⁾e-mail: mohammed_houari73@yahoo.com

Письма в ЖЭТФ том 112 вып. 5 - 6

2020

387

7^∗