THE CALCULATIONS AND ANALYSIS OF ELECTRONIC STRUCTURE OF CSPBX3 (X = F, BR, CL, I) PEROVSKITE WITH CUBIC STRUCTURE

• Main Author: Ulfa, Marisa
• Format: Theses
• Language: Indonesia
• Subjects: Fisika
• Online Access: https://digilib.itb.ac.id/gdl/view/41413
• Institution: Institut Teknologi Bandung

Metal Halide Perovskite AMX3 (A: inorganic or organic cation, M: metal cation (Pb or Sn), and X: halide anion) is a highly promising material as an alternative to organic-inorganic perovskite such as methylamine lead triiodide (MAPbI3). Although CsPbI3, as one of the AMX3 perovskite, yields efficiency lower than MAPbI3 based solar cells, CsPbI3 perovskites possess higher degree of stability toward humidity and oxidation. Considering the possibility of altering X with the elements from halide type, this thesis studies how this variation affects the electronic structure of CsPbX3 (cubic) as the means to elucidate the extent of these materials in photovoltaic applications. This study relies on the calculation of electronic structure using a software package based on density functional theory (DFT), known as Quantum ESPRESSO. Following the ab initio calculation with a range of parameters, convergent calculation is achieved and electronic structure corresponding to semiconductor characteristics is obtained. This is carried out by using PBE as the exchange correlations, along with Ultrasoft pseudopotential, setting energy and density cut-off to 45 Ry and 450 Ry, respectively, and 4x4x4 k-points The machine learning algorithm used for structural optimizations Broyden-Fletcher-Goldfarb-Shann0 (BFGS). The atomic relaxation uses 0 kbar pressure without external forces and the electron occupancy is calculated using Methfessel-Paxton and Fermi-Dirac wave function smearing. The computation results bandgap energy in range of 1.445 eV – 2.866 eV with the halide F having the highest band gap. Hence, CsPbI3 has the smallest bandgap and this gap is getting wider as the halide is altered to a smaller atom. The variation of halide anion has a significant effect to the electronic structure near the valence and conduction bands in terms of the contributions of orbitals density corresponding to the atomic species in this material.