SYNTHESIS, STRUCTURE CHARACTERIZATION AND THERMAL STABILITY OF ABX3 PEROVSKITES (A=METHYLAMMONIUM, B=PB/SN, X=BR/I)

• Main Author: Harsono, Yudi
• Format: Theses
• Language: Indonesia
• Subjects: Kimia
• Online Access: https://digilib.itb.ac.id/gdl/view/75474
• Institution: Institut Teknologi Bandung

Perovskite is a compound that has a general formula of ABX3, where A and B are cations and X is an anion, which produces a three-dimensional (3D) structure similar to the calcium titanate (CaTiO3) structure. In its development, there are derivatives of perovskite with 2D structures, which have the general formula A2BX4, as well as 1D (A3BX5) and 0D (A4BX6) structures. Perovskite halide compounds exhibit semiconductor properties, making them suitable for use as solar cell materials and optoelectronic materials. Lead halide perovskites, in particular, demonstrate excellent solar cell performance, achieving power conversion efficiencies (PCE) of up to 25.2%. However, lead is a hazardous and toxic element, necessitating research into alternative metals for its replacement. Additionally, the synthesis process of perovskites commonly involves the use of toxic organic solvents such as dimethylformamide (DMF), dimethyl sulfoxide (DMSO), acetonitrile (ACN), and gamma-butyrolactone (GBL), highlighting the need to explore more environmentally friendly solvent alternatives. In this study, four perovskite compounds, namely methylammonium lead bromide (MAPbBr3), methylammonium lead iodide (MAPbI3), methylammonium tin bromide (MASnBr3), and methylammonium tin iodide (MASnI3), were successfully synthesized using water as the solvent, with average overall yields above 64%. Characterization results using instrumentation and conventional techniques reveal that the synthesized perovskites have the general formula ABX3 (3D structure), where A = methylammonium, B = lead/tin, and X = iodide/bromide. Powder X-ray diffraction (PXRD) measurements indicate that the crystal lattice structures of MAPbBr3, MAPbI3, and MASnI3 are cubic, with lattice sizes of 5.918 Å, 6.286 Å, and 6.237 Å respectively. Each lattice unit consists of one MA cation, one Pb cation and three halide anions. While MASnBr3 exhibits an orthorhombic structure with lattice parameters of a = 5.905 Å, b = 8.360 Å, and c = 8.314 Å. In each lattice unit of MASnBr3, there are two MA cations, two Pb cations, and six halide anions. Thermal gravimetric analysis (TGA) results show that MAPbBr3 exhibits the highest thermal stability (300°C), followed by MAPbI3 (240 °C), MASnBr3 (180 °C), and MASnI3 (140 °C). Additionally, all synthesized perovskites are found to be anhydrous.