One-Dimensional Solar Cell Capacitance Simulator (1D-SCAPS) and n-i-p planar configuration have been employed for the simulation of the caesium tin iodide (CsSnI₃)-based perovskite solar cell (PSC) with titanium (IV) oxide (TiO₂) and copper thiocyanate (CuSCN) as the electron and hole transport materials respectively. The results obtained for the initially modeled PSC compared well with similar devices in the literature but marred with high recombination rate. As such, the defect density in the CsSnI₃ absorber was varied from 10¹³ cm^-3 to 10¹⁷ cm^-3 and enriched with SnCl₂ (additive) and Br⁻(dopant) respectively. This strategy ensured a reduced concentration of Sn⁴⁺ vacancy (V_Sn) in the CsSnI₃ absorber with improved carrier lifetime and diffusion length beyond 0.05 ns and 1.1µm by a magnitude of the order of 10³ and 10² respectively for the enriched CsSnI₃ –based PSC. For the optimized PSC, we recorded V_OC=1.289 V, J_SC=32.60 mA.cm^-2, FF=83.56% and PCE=35.12%.

Palm kernel shell and coconut shell have been combined in equal proportion to produce activated carbons for supercapacitor electrode and water filter. Microwave-assisted activation technique was employed for the production at a much shorter time (ranging from 5-10 min) and reduced cost compared to the conventional activation methods. Co-activator (mixture of NaCl and CaCl₂) was used to activate the sample for water filter with no added fillers while the sample for supercapacitor electrode was activated with KOH and NiO nanoparticles as fillers. Physical properties (such as density, ash content and moisture content) and Thermo-Gravimetric Analysis (TGA) were carried out to ascertain the quality of the activated carbons. In addition to the microstructural and structural investigations, surface functionalities, adsorption capability and electrochemical properties of the samples were also investigated. The surface chemistry, microstructure, structure and electrochemical properties of the produced activation carbon were investigated employing Fourier Transform Infra-Red (FTIR) Spectroscopy, Scanning Electron Microscopy (SEM), X-Ray Diffraction (XRD), Cyclic Voltammetry (CV) and Electrochemical Impedance Spectroscopy (EIS).The effectiveness of the activated carbon sample for water filter was tested for the removal of organic dye (methylene blue) from water contaminated with the organic dye via adsorption studies using the Freundlich model. Finally, the results; obtained from electrochemical studies, show that the activated carbon for supercapacitor electrode possesses good current response with high value of specific capacitance and it is a promising component for electrochemical devices.

Previously, we reported an investigation on Delonix regia dye extract as a natural sensitizer for TiO₂/DSC assembled with platinum counter electrode and low power conversion efficiency was recorded. This necessitated the current investigation on Delonix regia dye extract as a natural sensitizer for TiO₂/DSCs assembled with different counter electrodes. Platinum counter electrode was used for one of the DSCs while polyaniline (PANI) was used to replace platinum in the other DSC. The vitriol treated PANI thin film consisted of aniline mixed with potassium dichromate directly reacted on circular graphite foam. The conductivity and Hall coefficient were measured to be and respectively using ECOPIA Hall Effect Measurement System (HMS-3000 Version 3.52). Sequel to this, the DSCs were assembled and characterized using a standard overhead Veeco viewpoint solar simulator equipped with AM 1.5 filter to give a solar radiation of 1000 W/m² and coupled to a Keithley source meter (model 4200SCS) which was connected to the computer via GPIB interface for data acquisition. The overall solar power conversion efficiencies of 0.02% and 0.04% were obtained for TiO₂-DSC//Delonix regia dye//platinum electrode and TiO₂-DSC//Delonix regia dye//PANI electrode respectively. Delonix regia dye extract proved to be rather a poor sensitizer as can be seen by the low spectral absorption at lower energies with short circuit current density of 0.10mAcm^-2 and 0.11mAcm^-2 respectively. Nevertheless, a 10% decrease in the electron recombination via redox electrolyte and collection at the photoelectrode was observed for TiO₂-DSC//Delonix regia dye//PANI electrode and a 20% increase in the open circuit voltage (V_oc) was also observed. Finally, about 37% increase in the fill factor was observed for the TiO₂-DSC//Delonix regia dye//PANI electrode over TiO₂-DSC//Delonix regia dye//platinum electrode. This necessitated approximately 50% increase in the power conversion efficiency for the TiO₂-DSC//Delonix regia dye//PANI electrode over TiO₂-DSC//Delonix regia dye//platinum electrode.

We have demonstrated that activated carbon could be produced via microwave-assisted activation at a much shorter time (ranging from 2-5 min) and reduced cost compared to the conventional activation method embraced by most researchers in the production of activated carbon. The research work is not only limited to surface chemistry and adsorption studies but also includes structural, microstructural and electrochemical studies/investigations of the produced Nickel Oxide Filled Activated Carbon (NOFAC). Its uniqueness is tied to cost effectiveness and the use of agricultural waste product. Activated carbon filled with nickel oxide was prepared via microwave-assisted chemical activation using coconut shell, palm kernel shell and their mixture with potassium hydroxide as activating agent. The effect of the incorporation of NiO on the structure and surface chemistry of the raw materials after activation was studied employing Fourier Transform Infra-Red (FTIR) Spectroscopy, Transmission Electron Microscopy (TEM) and X-ray Diffraction (XRD) analysis. The electrochemical characteristics were investigated employing Cyclic Voltammetry (CV), Galvanostatic Charge-Discharge (GCD) analysis and Electrochemical Impedance Spectroscopy (EIS). The FTIR spectroscopy confirmed the existence of strong interfacial interaction between NiO and the host matrices showing creation and annihilation of absorption bands in the IR spectra with significant absorptions observed below 500cm-1 for nickel oxide. The TEM results showed that the microstructural evolution of host matrices is as a result of incorporation of NiO and activation using microwave power respectively. A follow-up with XRD confirmed the presence of anomalous graphite structure surrounded by traces of impurities resulting from the activating agent. Finally, the scan rate studies revealed activated palm kernel shell as the best candidate with better current response, higher value of specific capacitance and better electrochemical behaviour