INORGANIC HALIDE PEROVSKITE NANOCRYSTALS FOR OPTOELECTRONICS APPLICATION

Abstract

The work presented in this thesis discusses the significance of halide perovskite nanocrystals (NCs) in the field of optoelectronics. Halide perovskites are materials with the chemical formula ABX3, where A represents an organic or inorganic cation, B denotes a metal cation, and X is a halide ion. These nanocrystals exhibit remarkable optical and photoelectric properties, making them appealing for various applications because of their low cost and simple synthesis. Halide perovskite structures are categorized into organometallic halide perovskites (OHPs) and inorganic halide perovskites (IHPs) based on the type of A ion present. OHPs have shown promise but face challenges due to their instability, sensitivity to environmental factors, and low lattice energies. In contrast, IHPs, which replace organic functional groups with inorganic cations, exhibit improved stability and are considered more suitable for practical applications. A pioneering study by Protesescu et al. in 2015 focused on inorganic halide perovskite nanocrystals (IHPNCs). They successfully synthesized CsPbX3 (X = Cl, Br, I) NCs with controlled bandgap energies, tunable emission, and remarkable stability. This work generated increased interest among researchers in IHPNCs for their unique properties. IHPNCs have drawn significant focus in recent years due to their improved stability, superior photophysical properties, and defect-tolerant nature, which allows for high carrier mobility and efficient charge transport in various optoelectronic devices. The bandgap and size of halide perovskite NCs can be tuned through various approaches, including cation/anion exchange, ligand modification, and precursor concentration adjustment. Several approaches have been made to improve the stability of the perovskite NCs, including the perovskite NCs-polymer composite, with limited success. The exciton binding energy, a critical parameter for optoelectronic materials, is examined in this thesis which is not well understood due to the wide variation of structural properties. It determines the material's response to excitation and influences its optical characteristics. The research problem and motivation are presented, emphasizing halide perovskite nanocrystal research progress and its potential applications. However, challenges related to stability and optical properties persist. The research objectives include improving the stability and photoluminescence of perovskite NCs, understanding their structural and optical properties, and exploring their potential applications in photodetectors. This thesis highlights the growing interest in halide perovskite nanocrystals for their exceptional optical and electronic properties.