Recent achievements, based on lead (Pb) halide perovskites, have prompted comprehensive research on low-cost photovoltaics, in order to avoid the major challenges that arise in this respect: Stability and toxicity. In this study, device modelling of lead (Pb)-free perovskite solar cells has been carried out considering methyl ammonium tin bromide (CH₃NH₃SnBr₃) as perovskite absorber layer. The perovskite structure has been justified theoretically by Goldschmidt tolerance factor and the octahedral factor. Numerical modelling tools were used to investigate the effects of amphoteric defect and interface defect states on the photovoltaic parameters of CH₃NH₃SnBr₃-based perovskite solar cell. The study identifies the density of defect tolerance in the absorber layer, and that both the interfaces are 10¹⁵ cm⁻³, and 10¹⁴ cm⁻³, respectively. Furthermore, the simulation evaluates the influences of metal work function, uniform donor density in the electron transport layer and the impact of series resistance on the photovoltaic parameters of proposed n-TiO₂/i-CH₃NH₃SnBr₃/p-NiO solar cell. Considering all the optimization parameters, CH₃NH₃SnBr₃-based perovskite solar cell exhibits the highest efficiency of 21.66% with the V_oc of 0.80 V, J_sc of 31.88 mA/cm² and Fill Factor of 84.89%. These results divulge the development of environmentally friendly methyl ammonium tin bromide perovskite solar cell.

The photovoltaic performance of perovskite solar cells (PSCs) can be improved by utilizing efficient front contact. However, it has always been a significant challenge for fabricating high-quality, scalable, controllable, and cost-effective front contact. This study proposes a realistic multi-layer front contact design to realize efficient single-junction PSCs and perovskite/perovskite tandem solar cells (TSCs). As a critical part of the front contact, we prepared a highly compact titanium oxide (TiO₂) film by industrially viable Spray Pyrolysis Deposition (SPD), which acts as a potential electron transport layer (ETL) for the fabrication of PSCs. Optimization and reproducibility of the TiO₂ ETL were discreetly investigated while fabricating a set of planar PSCs. As the front contact has a significant influence on the optoelectronic properties of PSCs, hence, we investigated the optics and electrical effects of PSCs by three-dimensional (3D) finite-difference time-domain (FDTD) and finite element method (FEM) rigorous simulations. The investigation allows us to compare experimental results with the outcome from simulations. Furthermore, an optimized single-junction PSC is designed to enhance the energy conversion efficiency (ECE) by > 30% compared to the planar reference PSC. Finally, the study has been progressed to the realization of all-perovskite TSC that can reach the ECE, exceeding 30%. Detailed guidance for the completion of high-performance PSCs is provided.

Hybrid organometal halide perovskites such as methylammonium lead iodide (MAPbI₃) are a promising class of cost- and energy-efficient light absorption materials for thin-film photovoltaics. In this work, the preparation and characterization of MAPbI₃ nanoparticles (NPs) on TiO_x/indium tin oxide glass substrates using a simple spin-coating technique have been investigated. The NPs were prepared by spin-coating solutions of MAPbI₃ and the ionic liquid (IL) 1-hexyl-3-methylimidazolium chloride in N,N-dimethylformamide. Analysis of the resulting spin-coated films revealed that uniform spherical MAPbI₃ NPs with an average diameter of 540 nm were homogeneously distributed on the TiO_x substrates. MAPbI₃ films with similar crystallinity were observed irrespective of the inclusion of IL, as evident from the X-ray diffraction patterns of the films. However, addition of IL to the spin-coating solution facilitated the formation of homogenous nucleation sites and prevented rapid crystal formation of MAPbI₃. Therefore, the presence of an IL resulted in uniform thin films with good morphology.

In this study, phytochemical assisted nanoparticle synthesis was performed using Muntingia calabura leaf extracts to produce copper oxide nanoparticles (CuO NPs) with interesting morphology. Scanning electron microscope (SEM) and transmission electron microscope (TEM) analysis of the biosynthesized CuO NPs reveal formation of distinct, homogeneous, and uniform sized CuO nanorods structure with thickness and length of around 23 nm and 79 nm, respectively. Based on Fourier-transform infrared (FTIR) analysis, the unique combinations of secondary metabolites such as flavonoid and polyphenols in the plant extract are deduced to be effective capping agents to produce nanoparticles with unique morphologies similar to conventional chemical synthesis. X-ray diffraction (XRD) analysis verified the monoclinical, crystalline structure of the CuO NPs. The phase purity and chemical identity of the product was consolidated via X-Ray photoelectron spectroscopy (XPS) and Raman spectroscopic data which indicate the formation of a single phase CuO without the presence of other impurities. The direct and indirect optical band gap energies of the CuO nanorods were recorded to be 3.65 eV and 1.42 eV.