SYNTHESIS AND CHARACTERIZATION OF HYBRID COMPOUNDS (PMA)2SNI4, (PEA)2SNI4, AND (PEA)2SNBRX/I4-X

• Main Author: Safitri Anwari, Nelly
• Format: Theses
• Language: Indonesia
• Subjects: Kimia
• Online Access: https://digilib.itb.ac.id/gdl/view/68081
• Institution: Institut Teknologi Bandung

Hybrid compounds are compounds composed of organic and inorganic compounds. In (RNH3)2SnI4 material, (RNH3)+ acts as an organic cation and SnI42- as an inorganic complex anion. These compounds have many applications such as in solar cells, photodetectors, transistors, and Light Emitting Diodes (LEDs). This compound is being developed, one of which is a Pb-based hybrid compound which is known having high efficiency. However, the use of Pb makes this material toxic so it is necessary to modify it using other elements. Some metals that have a potential to replace Pb are Sn, Ge, Bi, and Cu. And in this study, Sn metal was used as the constituent element of the hybrid compound because accoding to some reports, this element has very similar characteristics to Pb and lower toxicity level. However, the replacement of Pb with Sn also has drawbacks, namely it can cause structural stability to decrease because Sn2+ tends to be oxidized to Sn4+ so efforts are made to prevent this problem by using H3PO2 which functions as a reducing agent and preventing oxidation. In this research, the synthesis of hybrid compounds by varying organic cations and halide ion substitution had been carried out in order to determine the changes in characteristics of the products. The organic cations used were phenyl methyl amine (PMA) and phenyl ethyl amine (PEA), while the halide anions were iodide and bromide. Synthesis of (RNH3)2SnI4 was carried out by dissolving SnO in 57% HI solution and adding H3PO2. After that, the amine is added and heated. The synthesized product is sensitive to air, so it needs to be stored in a closed container with nitrogen gas flowing. The synthesis of (PEA)2SnBrx/I4-x compound was carried out in the same way, but it was started by mixing two precursor solutions, namely (PEA)2SnI4 and (PEA)2SnBr4 with a mole ratio of 1:1. Next, the synthesized product was characterized using CHN Analyzer, Atomic Absorption Spectroscopy (AAS), Argentometry titration, and Energy Dispersive X-Ray (EDX) which were used to determine the molecular formula of the synthesized product, while Thermogravimetric Analyzer (TGA), X-ray Diffraction ( XRD), Photoluminescence (PL) spectroscopy, and Scanning Electron Microscope (SEM) were carried out to determine product characteristics such as thermal stability, crystallographic data, emission wavelength, and particle morphology. And the molecular formulas obtained for each product are (PMA)2SnI4.HI, (PEA)2SnI4.2HI, and (PEA)2SnBr0,75/I3,25.HI. All product’s diffractogram patterns show that the products have low crystallinity, multiphase or the phase is more than one, and amorphous. The substitution of halide I- with Br- causes a shift in the emission wavelength to a smaller direction or a blue shift. Computational studies had also been carried out to study the stability of (MA)2SnI4 compound as seen from the energy of the formation reaction. Simulations were carried out using two softwares, namely ORCA and Quantum Espresso. The results of calculations using ORCA for (MA)2SnI4 obtained a very high energy value so it is possible that the calculation result is not appropriate, while calculations using Quantum Espresso obtained the formation reaction energy for (PMA)2SnI4 of -84,681 kJ/mol which is more negative than (MA)2SnI4 of -83,918 kJ/mol.