SYNTHESIS OF FLUORESCENT PEROVSKITE NANOMATERIALS AND THEIR APPLICATIONS

Abstract

The thesis entitled “Synthesis of Fluorescent Perovskite Nanomaterials and their Applications” has been divided into Six chapters, Metal halide perovskites (ABX3) represent an important category of materials when considering optoelectronic applications including photovoltaic and light-emitting devices. Within the objective of the thesis, many potential strategies for material modification were studied, including metal substitutions, halide substitutions, and ligand substitutions. Analyses of the potential for these modifications to occur and their implications for structural and optoelectronic characteristics were conducted. In this thesis, the synthesis, composition, and characteristics of this family of perovskites are addressed extensively, with an emphasis on the crystal chemistry, mechanical properties, and structural variety of these materials. Despite extensive research on MA-based perovskites, there are still numerous unanswered concerns about lead-free perovskites. Compositional engineering was used to enhance stability and eliminate toxicity in the existing prototypical hybrid perovskites, concentrating on non-toxic bismuth (Bi) as a potential replacement for lead (Pb) in future photovoltaic materials. Chapter 1 This chapter details a brief review of the importance of metal halide perovskite as well as their synthesis and characteristics. This chapter explains the idea of the work as well as the reason behind it. The topics of nanotechnology, nanoscience and the behavior of nanoparticles are covered. It details the production of nanostructured materials as well as the classification of such materials. This chapter focuses mostly on inorganic-organic metal halide perovskite (IOHPs) as its primary research area. In this chapter, we will discuss several approaches to the synthesis of IOHPs. The atomic structure, as well as the physical, chemical, optical, and electrical characteristics of the metal halide perovskite, are the primary topics of this study. Nanoparticles made from IOHPs may be used in photovoltaic and optoelectronic applications. Chapter 2 We have synthesized a new class of organolead halide perovskite nanocrystals by solvent-free mechanochemical green approach. Simplicity, swiftness, reproducibility, and harmony with green chemistry credentials make the mechano-synthesis process a preferable approach to the synthesis of halide perovskites (HPs). We have developed a new combination of Abstract ii precursors incorporating nitrate ions into the MAPbBr3 perovskite core. While the presence of nitrate ions is evidenced by the FT-IR spectra, XRD data shows the formation of perovskite nanocrystals. By altering the precursor composition, the morphology of the nanocrystal (NCs) changes. Photoluminescence (PL) properties of these nanocrystals are preserved. Moreover, the stability of these nanocrystals is monitored for a long time, which shows that the incorporation of nitrate ions into the core of perovskite nanocrystal does not have any decremental effect on its stability. Nonetheless, this strategy to synthesize perovskite nanocrystals reduces solvent toxicity. Chapter 3 In this study, we have carried out the prior synthetic process and used only multifunctional Cetyl trimethylammonium bromide (CTAB) to synthesize hybrid organic-inorganic metal halide perovskite, HPs, (MAPbX3, X=Br, I). Steady-state photoluminescence, X-ray diffraction (XRD), and time correlate single-photon count (TCSPC) were performed to investigate the optical and structural features of mechanochemically produced perovskite. The thermogravimetric analysis informs about the thermal stability of the nanocrystals. X-ray diffraction analysis reveals that mechanochemically synthesized HPs show high crystallinity and phase purity with stability over a period of time. The photoinduced current response of the perovskite reveals an excellent increase in photoconductivity when exposed to light (with a 1 V bias). The device fabricated of perovskite witnessed the prompt photoresponse under light illumination and temporally-stable photocurrent over the multiple cycles of light irradiation. The synthesized materials are useful for photovoltaic applications because of their phase purity, low bandgap, nanoscale size, long-term stability, and easy-to-produce approach. Chapter 4 In this work we have used ligand-assisted reprecipitation to synthesis perovskite graphite composite. High luminescent methylammonium lead halide perovskite nanocrystals (PNCs) have attracted considerable research interest due to their alluring properties which can be tuned as per the morphological variations. Charge transfer excitons (CTEs) are a good representation of the capacity of semiconductor materials to tune their properties. We report here that CTEs may be generated successfully in graphite: PNCs composites functioning as host-guest components. These hybrid perovskite nanocrystals are embedded in graphite sheets that are unfunctionalized. The PL spectrum demonstrated that graphite significantly reduces the luminescence intensity of perovskite nanocrystals. The morphologies of perovskite nanocrystals are developed in such a manner that they may be readily incorporated onto the surface of graphite sheets to facilitate effective charge transfer. Chapter 5. This work demonstrates the possibility of making double perovskite (DPs) using short-chain carboxylic acids. First, employing oleic acid in ambient conditions, we effectively produced Cs2AgBiX6 double perovskite at room temperature. We thoroughly examine their morphological, crystallographic, and optical properties. Following that, we intend to synthesize Cs2AgBiBr6 utilizing short-chain carboxylic acid instead of the conventional long-chain acids and amines. This might be a potential study for double perovskite material under ambient conditions and at room temperature. Cs2AgBiBr6 may be envisioned as a potent photocatalyst for the degradation of Rhodamine B when subjected to visible light.