Ab Initio Investigation for Solar Technology on the Optical and Electronic Properties of Double Perovskites Cs₂AgBiX₆(X=Cl, Br, I)

Abstract

In the present paper, the first principal computations have been made to explore the optical and electronic characteristics of Cs 2 AgBiX 6 (X=Cl, Br, I) double perovskite. To determine the energy of the band gap, we have used the GGA potentials. The values found for I, Cl, and Br are 0.815 eV, 1.417 eV, and 1.836 eV, respectively. According to our numerical simulation, the Cs 2 AgBiX 6 (X=Cl, Br, I) have an important light absorption coefficient, exceeding a value of 10 4 cm −1 which makes it a viable absorbing material for Solar Systems. Other optical properties such as refractive index and dielectric function were also computed in this work. We have found ε re = 7.72, ε re = 5.22, and ε re = 4.12 for I, Cl, and Br respectively. About the equivalent static refractive indices values of Cs 2 AgBiX 6 (X=Cl, Br, I), we have found n 0 = 2.77, n 0 = 2.28, and n 0 = 2.03 for I, Br, and Cl respectively. Also, we have used SCAPS software to simulate solar cells made of Cs 2 AgBiX 6 (X=Cl, Br, I). The efficiency, fill factor and other parameters have been computed. Our results are 1.52 V, 1.08 V, 0.54 V, and 16.56 mA∕cm 2 , 28.65 mA cm −2 , and 50.25 mA cm −2 in V oc and J sc for <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>C</mml:mi> <mml:mi>l</mml:mi> <mml:mo>,</mml:mo> <mml:mspace width="0.25em"/> <mml:mi>B</mml:mi> <mml:mi>r</mml:mi> <mml:mo>,</mml:mo> </mml:math> and <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>I</mml:mi> </mml:math> respectively. The efficiency computed are 22.85%, 27.46%, and 22.46% for <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>C</mml:mi> <mml:mi>l</mml:mi> <mml:mo>,</mml:mo> <mml:mspace width="0.25em"/> <mml:mi>B</mml:mi> <mml:mi>r</mml:mi> <mml:mo>,</mml:mo> </mml:math> and <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>I</mml:mi> <mml:mo>,</mml:mo> </mml:math> respectively. These estimated results demonstrate the potential of Cs 2 AgBiX 6 (X=Cl, Br, I) as a potentially useful substance in solar cells.