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.

Generation of energy across the world is today reliant majorly on fossil fuels. The burning of these fuels is growing in line with the increase in the demand for energy globally. Consequently, climate change, air contamination, and energy security issues are rising as well. An efficient alternative to this grave hazard is the speedy substitution of fossil fuel-based carbon energy sources with the shift to clean sources of renewable energy that cause zero emissions. This needs to happen in conjunction with the continuing increase in the overall consumption of energy worldwide. Many resources of renewable energy are available. These include thermal, solar photovoltaic, biomass and wind, tidal energy, hydropower, and geothermal. Notably, tidal energy exhibits great potential with regard to its dependability, superior energy density, certainty, and durability. The energy mined from the tides on the basis of steady and anticipated vertical movements of the water, causing tidal currents, could be converted into kinetic energy to produce electricity. Tidal barrages could channel mechanical energy, while tidewater river turbines can seize the energy from tidal currents. This study discusses the present trends, ecological effects, and the prospects for technology related to tidal energy.

Synthesis of copper oxide (CuO) nanostructures via biological approach has gained attention to reduce the harmful effects of chemical synthesis. The CuO nanostructures were synthesized through a green approach using the Garcinia mangostana L. leaf extract and copper (II) nitrate trihydrate as a precursor at varying calcination temperatures (200–600 °C). The effect of calcination temperatures on the structural, morphological and optical properties of CuO nanostructures was studied. The red shifting of the green-synthesized CuO nanoparticles’ absorption peak was observed in UV-visible spectrum, and the optical energy bandgap was found to decrease from 3.41 eV to 3.19 eV as the calcination temperatures increased. The PL analysis shown that synthesized CuO NPs calcinated at 500 °C has the maximum charge carriers separation. A peak located at 504–536 cm⁻¹ was shown in FTIR spectrum that indicated the presence of a copper-oxygen vibration band and become sharper and more intense when increasing the calcination temperature. The XRD studies revealed that the CuO nanoparticles’ crystalline size was found to increase from 12.78 nm to 28.17 nm, and dislocation density decreased from 61.26 × 10¹⁴ cm⁻¹ to 12.60 × 10¹⁴ cm⁻¹, while micro strain decreased from 3.40 × 10⁻⁴ to 1.26 × 10^–4. From the XPS measurement, only CuO single phase without impurities was detected for the green-mediated NPs calcinated at 500 °C. The morphologies of CuO nanostructures were examined using FESEM and became more spherical in shape at elevated calcination temperature. More or less spherical nanostructure of green-mediated CuO calcinated at 500 °C were also observed using TEM. The purity of the green-synthesized CuO nanoparticles was evaluated by EDX analysis, and results showed that increasing calcination temperature increases the purity of CuO nanoparticles.