Multi-dimensional Lead-Free Halide Perovskites in Optoelectronics and Photo(electro)catalysis

Mal, Santanu (2026) Multi-dimensional Lead-Free Halide Perovskites in Optoelectronics and Photo(electro)catalysis. PhD thesis, Indian Institute of Science Education and Research Kolkata.

Text (PhD thesis of Santanu Mal (19RS010)) 19RS010.pdf - Submitted Version Restricted to Repository staff only Download (15MB)

Abstract

Metal halide perovskites (MHPs) have garnered considerable attention for optoelectronic, photovoltaic, and photocatalytic applications owing to their large UV-visible absorption coefficients, long carrier diffusion lengths, favorable charge-transport optical properties, and intrinsic defect tolerance behavior. However, the environmental and health concerns associated with lead toxicity, have motivated for intensive research toward the development of lead-free halide perovskites as sustainable alternatives. This thesis consists of seven chapters, including four research working chapters, and focuses on elucidating the structure-property functional relationships in multi-dimensional lead-free halide perovskites, with emphasis on their optoelectronics and photo(electro)catalytic applications. Chapter 1 presents an overview of renewable energy conversion and storage technologies, with primarily focus on solar energy harvesting, followed by a brief discussion on the fundamental properties of MHPs, their defect-tolerant nature, concerns related to environmental stability, synthetic strategies, and finally emerging applications in single component light emission, visible light photodetection, and photo(electro)catalysis. Chapter 2 describes the synthesis protocols, device fabrication procedures, and comprehensive physicochemical, structural, and optical characterization techniques of MHPs, employed in this thesis works. Chapter 3 reports a new zero-dimensional zirconium halide phosphor, (PPh₄)₂ZrCl₆, comprising isolated [ZrCl₆]²⁻ octahedra, which exhibits intrinsic single-component white-light emission with excitation- and pressure-dependent tunability arising from dual singlet-triplet self-trapped excitonic states (STEs). Chapter 4 investigates bulk and quantum-confined Cs₄CuSb₂Cl₁₂ microcrystals and nanocrystals, demonstrating their size-dependent optical properties and out-of-plane photodetector performance. Chapter 5 explores spin-polarized Mn-doped Cs₃Sb₂Br₉ nanocrystals, where external magnetic field induced spin polarization markedly enhances biomass coupled CO₂ photoreduction by mitigating charge-carrier recombination. Chapter 6 demonstrates water-stable vacancy-ordered Cs₂PtX₆ (X = Cl, Br, I) microcrystals as bifunctional photoelectrocatalysts for oxygen evolution and oxygen reduction reactions, highlighting their high thermal stability, superior aqueous durability and their potential application in photorechargeable Zn–air batteries. Chapter 7 summarizes the major findings based on the thesis works and outlines future research prospects.

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