1 Chapter 1Figure 1.1 The different recombination processes in semiconductors.Figure 1.2 Flowchart showing steps for calculation using ASA adapted from [3].Figure 1.3 Action panel of SCAPS.Figure 1.4 Solar cell definition panel of SCAPS.Figure 1.5 Layer properties panel in SCAPS.Figure 1.6 Screenshot of energy bands panel window in SCAPS.

      2 Chapter 2Figure 2.1 Generations of the photovoltaic cells.Figure 2.2 Evolution of perovskite solar cell from reduction of size of light absorbing layer from...Figure 2.3 The crystal structure of the perovskite [6].Figure 2.4 Working of the perovskite solar cell [11].Figure 2.5 Depiction of two main types of PSC [12].Figure 2.6 Schematic diagram of four types of perovskite solar cell...Figure 2.7 Transitions in direct and indirect semiconductor [33].Figure 2.8 Open-circuit voltage (Voc) versus optical band gap (Eg)...

      3 Chapter 3Figure 3.1 Schematic diagrams of mesoscopic heterojunction solar cell structure ...Figure 3.2 Schematic of the solvent engineering process in the one-step depositi...Figure 3.3 Schematic diagram of the sequential-deposition technique: Dipping in ...Figure 3.4 Schematic diagram of perovskite layer from compact PbI₂ (top) and por...Figure 3.5 Scanning electron microscope images of PbI₂ films...Figure 3.6 Nucleation and growth mechanism (a) without and (b) with MAI-capped P...Figure 3.7 Schematic view of the (a) HCM crystallization and (b) conventional crystallization...Figure 3.8 Schematic view of conventional crystallization (top) and HCM-crystall...Figure 3.9 Growth mechanism of perovskite layer on hydrophilic vs hydrophobic la...Figure 3.10 Contact angles of the Porphyrin (left) and Cobalt-Porphyrin (right) ...Figure 3.11 SEM images of perovskite layer deposited on (a) Porphyrin and (b) Co...Figure 3.12 Schematic of the solvent vapor annealing method.Figure 3.13 Schematics of the interdiffusion process and solvent vapor annealing...

      4 Chapter 4Figure 4.1 (a) Diagrammatic depiction of AVC process for the growth of single crystals...Figure 4.2 Diagrammatic depiction of ITC technique for the formation...Figure 4.3 (a) Schematic of the experiment examination...Figure 4.4 Schematic illustration of MITC technique...Figure 4.5 (a) Schematic depiction of the heating process utilizing homothermal aluminum block...Figure 4.6 (a) Illustrative diagram of TSSG method...Figure 4.7 (a) Illustrative diagram of BSSG method along with the obtained...Figure 4.8 (a) Illustrative diagram of BG technique. Reproduced from [40] with permission...Figure 4.9 (a) Illustrative diagram of SE technique...

      5 Chapter 5Figure 5.1 Typical lattice structure of a perovskite.Figure 5.2 Schematic illustration of characterization techniques for PSCs.Figure 5.3 GIXRD spectra (open cycle) around the (110) peaks for the r-perovskite...Figure 5.4 2D GIXRD profiles of perovskite films on...Figure 5.5 In situ XRD patterns. (a–d) Typical diffraction patterns of...Figure 5.6 In situ X-ray diffraction of perovskite annealing at...Figure 5.7 Schematic illustration of synchrotron-based X-ray scattering techniqu...Figure 5.8 Schematic of XAS including the pre-edge, XANES, and EXAFS regions...Figure 5.9 Measured and calculated XANES spectra of C K-edge of MAPbI₃ film...Figure 5.10 Hypothesized process of forming a CH₃I-PbI₂ defect site...Figure 5.11 EXAFS spectra of CsPbBr₃ (black) and CsPb_0.93Cu_0.07Br₃ (red)...

      6 Chapter 6Figure 6.1 Cubic geometry of perovskite oxide with the general formula of ABO₃ t...Figure 6.2 Schematic presentation of cubic crystal of halide perovskite with the...Figure 6.3 PCE for PSCs from 2006 to 2020, data obtained from Best Research-Cell...Figure 6.4 Schematic presentation of solid-state device architecture of (a) mesoscopic regular n-i-p...Figure 6.5 Schematic presentation of (a) solid-state device, (b) cross-section structure...Figure 6.6 (a) Diffuse reflectance spectrum, (b) Transformed Kubelka-Munk spectrum...Figure 6.7 (a) XRD pattern of prepared CsPbI₂Br perovskite film at different temperatures...Figure 6.8 (a) Cross-sectional SEM image of the CsPbI₂Br perovskite film with HTL and ETL on FTO...Figure 6.9 (a) Crystal structure of MAPbI₃ in distorted tetragonal phase...Figure 6.10 (a) XRD pattern and (b) crystal of MASnI₃ perovskite film showing tetragonal conformation...

      7 Chapter 7Scheme 7.1 Fundamental mechanism of semiconductor-mediated