Optik 159 (2018) 229–244 Contents lists available at ScienceDirect Optik j ourna l ho me pa ge: www.elsevier.de/ijleo Original research article First principles investigation of optoelectronic properties of ZnXP 2 (X = Si, Ge) lattice matched with silicon for tandem solar cells applications using the mBJ exchange potential Hamza Bennacer a,b,∗ , Abdelkader Boukortt b , Said Meskine b , Moufdi Hadjab c , Mohamed Issam Ziane d , Ali Zaoui e a University of M’sila, Faculty of Technology, 28000, M’sila, Algeria b Elaboration and Characterization Physical Mechanics and Metallurgical of Material, Laboratory, ECP3M, Electrical Engineering Department, Faculty of Sciences and Technology, Abd elhamid Ibn Badis University, Mostaganem, 27000, Algeria c Thin Films Development and Applications Unit UDCMA, Setif-Research Center in Industrial Technologies CRTI, Algiers, Algeria d Research Center in Semi-conductor Technologies for Energetic (CRTSE), Division of Semi-conductors Crystalline Growth and Metallurgical Processes (CCPM/CSM), Algiers, Algeria e Laboratoire de physique computationnelle des matériaux (LPCM), Université Djillali Liabès, Sidi Bel-Abbès, 22000, Algeria a r t i c l e i n f o Article history: Received 29 December 2017 Accepted 21 January 2018 Keywords: FP-LAPW mBJ Chalcopyrite Electronic band structure Linear optical properties a b s t r a c t II-IV-V 2 materials are attractive compounds for optoelectronic, photonic and photovoltaic applications due to their valuable ternary chemistry. A primary technological challenge in photovoltaics is to find and develop a lattice matched efficient material to be used in combination with silicon for tandem solar cells. ZnSiP 2 and ZnGeP 2 chalcopyrites are promising semiconductors that could satisfy these criteria. Particularly, ZnSiP 2 is known to have bandgap energy of ∼2 eV and a lattice mismatch with silicon of 0.5%. In this work, the first principle calculations have been performed to investigate the structural, electronic and optical properties of ZnSiP 2 and ZnGeP 2 in chalcopyrite structure within the Full Potential- Linearized Augmented Plane Wave (FP-LAPW) method based on the Density Functional Theory (DFT) as implemented in WIEN2K code. The local Density approximation (LDA) of Perdew and Wang was used as exchange-correlation potential to calculate the structural proprieties. Furthermore, the recently modified Becke-Johnson (mBJ) functional of Tran and Blaha was also employed to compute the electronic and optical properties in order to get best values of the band gap energy and some better degree of precision. The complex dielectric function, the complex refractive index, reflectivity, absorption coefficient, and the optical conductivity were calculated to illustrate the linear optical properties of both com- pounds ZnSiP 2 and ZnGeP 2 . At last, the obtained results indicate that ZnSiP 2 and ZnGeP 2 are attractive materials in optoelectronic devices especially as a lattice matched material with silicon for tandem solar cells applications. © 2018 Elsevier GmbH. All rights reserved. ∗ Corresponding author at: University of M’sila, Faculty of Technology, 28000, M’sila, Algeria. E-mail address: hamza.bennacer28@yahoo.fr (H. Bennacer). https://doi.org/10.1016/j.ijleo.2018.01.079 0030-4026/© 2018 Elsevier GmbH. All rights reserved.