Density functional theory study of mixed halide influence on structures and optoelectronic attributes of CsPb(I/Br)<sub>3</sub>
Ahmed S. Jbara, Junaid Munir, Bakhtiar Ul Haq, Muhammad Saeed
Abstract
This paper reports on the influence of the bromine (Br) atoms substitution on the structures and optoelectronic traits of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:msub> <mml:mtext>CsPbI</mml:mtext> <mml:mn>3</mml:mn> </mml:msub> </mml:mrow> </mml:math> , wherein the density functional theory (DFT) simulation was performed, using all electrons full potential linearized augmented plane-wave method. Furthermore, the generalized gradient approximation, local density approximation, and modified Becke–Johnson exchange-correlation potential were used to improve the optimization and band structure calculations. The calculated lattice constants of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:msub> <mml:mtext>CsPbI</mml:mtext> <mml:mn>3</mml:mn> </mml:msub> </mml:mrow> </mml:math> and <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:msub> <mml:mtext>CsPbBr</mml:mtext> <mml:mn>3</mml:mn> </mml:msub> </mml:mrow> </mml:math> were consistent with the experimental values. All the studied compounds revealed wide and direct bandgap energies at the R-symmetry point, which varied from 1.74–2.23 eV. The obtained refractive indices of the <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:msub> <mml:mtext>CsPbI</mml:mtext> <mml:mn>3</mml:mn> </mml:msub> </mml:mrow> </mml:math> , <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:msub> <mml:mtext>CsPbBrI</mml:mtext> <mml:mn>2</mml:mn> </mml:msub> </mml:mrow> </mml:math> , <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:msub> <mml:mtext>CsPbIBr</mml:mtext> <mml:mn>2</mml:mn> </mml:msub> </mml:mrow> </mml:math> , and <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:msub> <mml:mtext>CsPbBr</mml:mtext> <mml:mn>3</mml:mn> </mml:msub> </mml:mrow> </mml:math> compounds were correspondingly 2.265, 2.245, 2.090, and 2.086. Present findings may contribute towards the development of experimental studies on the proposed compounds with controlled properties useful for the solar cells.