SYNTHESIS, CHARACTERIZATION AND STABILITY ENHANCEMENT OF INORGANIC FLUORESCENT PEROVSKITE NANOMATERIALS

Abstract

The aim and purpose of the thesis are covered in the "Introduction" part which is described in chapter 1. It explains the evolution of perovskite materials. This chapter describes the procedures for synthesizing metal halide perovskite. It focuses on the lead-free metal halide perovskite's atomic structure, as well as its physical, chemical, optical, and morphological characteristics. Here, we describe potential application of perovskite nanoparticles in photovoltaics and optoelectronics. In chapter 2, CsPbX3 perovskite nanocrystals are effectively synthesized using non-toxic aromatic amino acids as a capping ligand. The aromatic amino acids are used in the synthesis of CsPbX3 nanocrystals, where the carboxylic and amine groups work in concert with the phenyl residue to create nanocrystals with intense fluorescence property. The experimental findings exhibit the long-lasting stability of perovskite nanocrystals and have emissive behavior across the whole visible spectrum. Also, the morphology of the nanocrystals has been tuned. We have used a variety of characterization approaches to investigate more about the characteristics of the nanocrystals in the solid and solution phases. In chapter 3, we have described the synthesis of an inorganic COF along with the COF@perovskite composite under atmospheric conditions. The COF@MAPbBr3 composite is extremely stable in both ambient conditions and polar solvents like methanol. We have performed a number of characterization techniques to ensure the formation of the material. The XRD and IR spectra exhibit the presence of COF in the composite, which may protect the perovskite materials and keep them stable in ambient conditions. In chapter 4A, we have investigated various properties of lead-free Cs2AgBiCl6 and Cs2AgBiBr6 double perovskite microcrystals in both organic and an aqueous-organic medium. Our research focuses on both eliminating lead toxicity and investigating perovskite material stability in aquatic environments. The addition of water can increase the emission intensity and change the morphology of the synthesized materials. In chapter 4B, we have described a solution-based synthesis of stable pristine and Cu2+ doped Cs2AgBiCl6 double perovskite. The bare and Cu-doped double perovskites have been characterized using a variety of techniques, including powered XRD, electron microscopic examination, X-ray photon spectroscopy. The EPR, SEM-EDX, and ICP-MS studies demonstrate that Cu ions are present in the produced materials. The thermal and ambient stability of the compounds is also examined. We come to the conclusion that Cu doping causes a progressive dampening of fluorescence intensity. In chapter 5, we have reported the water-assisted synthesis of the lead-free Cs2AgInCl6 double perovskite nanocrystals. We have developed an AND logic gate that is dependent on the fluorescence of the nanocrystals using a variety of the solvents used during the synthesis. In response to UV rays, the produced nanocrystal becomes photosensitive. The UV light radiation causes to change the colour of the nanocrystals from white to orange-white. The XRD analysis is used for the structural elucidation. Several studies have been performed to investigate the stability and shape of the nanocrystals. Also, we have successfully created a luminous keypad lock with a special password. In chapter 6, we have described a solution-based method for producing 2D tin halide (OleylAm)2SnBr4 (OleylAm = Oleylammonium cation) perovskites nanocrystals (like A2BX4) that are extremely emissive and show orange-colored emiision. The quasi-spherical material consists of a broad emission with a large Stoke shift and a thermally stable photoluminescence property. In this case, an organic cation (oleylamomium cation) functions as an A site and that causes the massive Stoke shift and broad emission in the nanocrystals and its insulating property provides the nanocrystals a high degree of stability in both aqueous and ambient conditions. The highly luminous, lead-free, stable 2D tin halide perovskite nanomaterial has also been used in a photoresponse investigation.