ELECTRONIC STRUCTURE AND OPTICAL PROPERTIES STUDY OF ABX3 PEROVSKITE (A = CH3NH3, Cs; B = Pb, Sn; X = Br) BASED ON DENSITY FUNCTIONAL THEORY

• Main Author: Suryana
• Format: Final Project
• Language: Indonesia
• Subjects: Fisika
• Online Access: https://digilib.itb.ac.id/gdl/view/42973
• Institution: Institut Teknologi Bandung

In this research we present calculations of electronic structure and optical properties of perovskite ABX3 (A = CH3NH3 (= MA), Cs; B = Pb, Sn; X = Br) based on DFT. The calculations were done for cubic unit cell of MAPbBr3, MASnBr3, CsPbBr3, and CsSnBr3 with lattice constants determined based on experimental results. Generalized gradient approximation (GGA) exchange-correlation functional employing Perdew-Burke-Ernzerhof (PBE) method and a norm-conserving pseudopotential were used in calculations. As results, crystal structure, electronic structure, and optical properties are presented. The relaxed crystal structures show significant change especially on MA(Pb/Sn)Br3 systems, due to presence of CH3NH3. Band structure calculation results in bandgap estimation with differences to the experimental bandgap up to 0.5 eV for (MA/Cs)PbBr3 systems and 1.3 eV for (MA/Cs)SnBr3 systems. The density of states (DOS) profile of each system shows the significant effect of Pb (or Sn) and Br on states near the conduction and valence band edge. Meanwhile, optical properties calculation including the complex dielectric and refractive index function, as well as the electron energy loss (EEL) function reveals the strong influence of Pb/Sn in energy range below ~5 eV. We found the similar effect of MA/Cs in energy range above ~5 eV, which also contributes on plasmonic state peak positions.