Fabrication and characterization of metal oxide nanostructured thin film for photovoltaic application.

Doctoral Degrees (Mechanical Engineering). University of KwaZulu-Natal. Durban, 2018.This study focused on fabrication and characterization of nanostructured metal oxide heterojunction solar cells for photovoltaic application. The study involved experimental fabrication of the device and modelling and theoretical validation of the fabricated device. The laboratory experiment was carried out by fabricating and characterizing nanostructured metal oxide thin film based solar cells using chemical spray pyrolysis and magnetron sputtering deposition techniques. The study included device design, materials tuning, process development, device characterization, device simulation, device reliability testing, and device circuit demonstration. The study covers the whole course of the device lithography and development. The spray pyrolysis method was used for depositing nickel oxide (NiO) thin films. Scanning electron microscope (SEM), energy dispersive X-ray powder diffraction (XRD), and Fourier transform infrared microscopy (FTIR) were used to characterize the films and four-point probe for the final device. Experimental optimization was conducted on the films with a focus on predeposition, deposition and post-deposition. The optimized result was used to fabricate a metal oxide NiO/TiO2 P-N heterojunction solar cell using spray pyrolysis and magnetron sputtering techniques. The optoelectronic properties of the heterojunction were determined. The fabricated solar cell exhibited 16.8 mA for the short circuit current, 350 mV open circuit voltage, 0.39 fill factor and conversion efficiency of 2.30 % under 100 mW/cm2 illumination. The result obtained from the experiment was compared and evaluated with the simulated results. The theoretical understanding of the device was modelled and theoretically validated. Theoretical understanding of the solar cell was established and thereafter the fabricated device modelled using solar cell analysis programs (SCAPxD). The working points used for the modelling included a temperature of 350 oC, illumination of 100mW/cm2, the voltage range of 0 volts to 1.5 volts. The output gave filled factor (FF) of 0.38 % which validated the experimental results. This study is a boosts in the quest to develop low-cost, environmentally friendly and sustainable solar cells materials and deposition method especially in developing and low-income countries that are experiencing electricity shortage using nanostructured metal oxide

Powering Africa using an off-grid, stand-alone, solar photovoltaic model

Abstract: Over 90 % of Sub-Saharan Africa is without electricity access. The rural areas of the few African countries with access lack electricity. Studies have suggested that solar energy systems hold the key to powering the continent. Although, a vast population currently operate fossilfuel powered generators to meet their basic electricity needs. The study is designed for a 2- bedroom flat inhabited by an average Africa family. A residential building in Akure, Ondo State, Southern Nigeria has this model installed in a stable and reliable condition. The proposed solar photovoltaic model is composed of solar panels, Direct Current (D.C) cables, charge controller, solar batteries, solar inverter, solar bulbs and instrumentation gadgets. The model is an optimum size solar Photovoltaic installation with a maximum power input of 1,800 W. The maximum allowable load is 1,000 W and a maximum charging D.C voltage of 28.2 V. The solar-powered system is equipped with a set of six (6) 300 Watts monocrystalline solar panels. A commercial maximum power point tracking (MPPT) charge controller was used for this model. Two (2) units of Deep Cycle AGM Solar Batteries connected in series are installed for the solar photovoltaic system. A pure sine wave solar inverter was used in the developed solar PV model to transform D.C electricity available in the batteries to A.C electricity. Themodel is a flexible one which could be scaled up as may be desired or required. The solar photovoltaic model has a very high prospect for powering Africa. The model has ample potentials to fulfil economic, social and environmental objectives which qualifies it as a sustainable energy option to improve the quality of life. The implementation of this form of sustainable energy will open even development of the continent and end the electricity woes of the populace

Modeling of Heat Transfer in 2D SLAB

Heat transfer in slab is a very important factor especially in the Africa continent. This work modeled the heat transfer in a 2D Slab. It used the Finite Difference Method (FDM) technique. Lines of code were written in Octave and can also be executed in Mat Lab and graph generated. KEYWORDS: finite difference method (FDM), heat, 2d slab, modelin

Biochar and Application of Machine Learning: A Review

This study discusses biochar and machine learning application. Concept of biochar, machine learning and different machine learning algorithms used for predicting adsorption onto biochar were examined. Pyrolysis is used to produce biochar from organic materials. Agricultural wastes are burnt in regulated conditions to produce charcoal-like biochar using pyrolysis. Biochar plays a major role in removing heavy metals. Biochar is eco-friendly, inexpensive and effective. Increasing interest in biochar is due to stable carbon skeleton because of ease of sourcing the precursor feedstock and peculiar physicochemical. However, artificial intelligence is a process of training computers to mimic and perform duties human. Artificial intelligence aims to enable computers to solve human challenges and task like humans. A branch of artificial intelligence that teaches machine to perform and predict task using previous data is known as machine learning. It uses parameters called algorithms that convert previous data (input) to forecast new solution. Algorithms that have been used in biochar applications are examined. It was discovered that neural networks, eXtreme Gradient Boosting algorithm and random forest for constructing and evaluating the predictive models of adsorption onto biochar have all been used for biochar application. Machine learning prevents waste, reduces time and reduces cost. It also permits an interdisciplinary means of removing heavy metals

Modeling of fabricated NiO/TiO2 P-N heterojunction solar cells.

Research articles.This paper reports modelling and theoretical validation of a fabricated NiO/TiO2 P-N heterojunction solar cell. The solar cell equations were modelled and thereafter theoretical validation of the fabricated solar cells was performed. Modelling tools were used to validate the influence of NiO material features such as deposition temperature, voltage and defect densities on the performances of an ITO/TiO2/NiO heterojunction solar cell structure. The working points used included a temperature of 350 oC, illumination of 1000 W/m2 using an AM1.5 lamp, with voltage range of 0 to 1.5 volts. The output gave Voc of 0.1445 V, Jsc of 247.959195E-6 mA/cm2 and FF of 37.87 % and Voc 0.7056 and Jsc 28.366911 mA/cm2 when both contacts were added. This opens a new frontier for modelling of metal oxide based thin film solar cells especially NiO thin film solar cells. These findings enhance the quest to develop affordable and sustainable energy and encourage further research in solar cell technologies in low-income countries

Solar cells and global warming reduction.

Research article.This study proposes one way of addressing the issue of climate change and pollution using solar cells. The quality of life in developing and low-income countries is on the decline because of air pollution. Energy has a role to play in the quality of life and reduction of air pollution especially in those countries. A reduction in the usage of fossil fuels and biomass in these countries will help decrease the air pollution and emissions generated by such energy sources. About 1 million solar lanterns are capable of reducing greenhouse gas emissions by over 30 000 tons. The role of eco-friendly solar cells in elimination of air pollution cannot be overstated

Numerical analysis and performance improvement of nanostructured Cu2O/TiO2 pn heterojunction solar cells using SCAPS

Abstract: This paper reported numerical analysis and performance improvement of nanostructured Cu2O/TiO2 pn heterojunction solar cells. Metal oxides thin films including Copper oxides are promising materials for photovoltaic applications. Although, the efficiency is still lower than other solar cells materials. This paper focused on improving the efficiency of Cu2O/TiO2 solar cells using SCAPS simulation tool. This was done by varying the effect of film surface thickness and effect of varying deposition temperature on the solar cells. The aim of the study is to serve as a theoretical guide for laboratory research on the improvement of efficiency of Cu2O metal oxide solar cells. The solar cells equations were modelled and thereafter theoretical validation of the nanostructured metal oxides was performed. The model working points input power of 100 mW/m2 using an illumination of AM1.5 lamp. The modelled solar cell exhibits a short-circuit current (Jsc) of 26.57 mA/cm2, 0.7188 V open-circuit voltage (Voc), fill factor (FF) of 70, and 13.37% efficiency (η). A value of 2.30 eV was recorded for the band gap. Also, electron affinity and Nyquist plot were obtained for the solar cells. Solar cells with thin absorber surface thickness will result in lower fabrication cost. This will open a new frontier for modelling of metal oxide based thin films solar cells especially Cu2O thin films solar cells

Development of Laboratory-Scale Salt Bath Furnace

A salt bath furnace was developed using electrical heating as source of heat which can be used in tertiary institution laboratories as well as by small and medium scale enterprises (SMEs).The salt bath was designed and manufactured virtually using CAD/CAM procedures, after which the production and assembling was carried out. A Material selector software aided in the materials selection, where mild steel was selected as the material for the casing, while other materials for the construction were selected based on functions and properties of the materials, cost considerations and ease of fabrication into component parts. The performance of the furnace was evaluated and, it was observed that the salt bath furnace has relatively fast heating rate of 16.670C/min when compared to conventional brands of salt bath and muffle furnaces that are available in the market. The furnace also has good heat retaining capacity and uniform heating rate. Keywords: Salt bath furnace, Heating Rate, CAD/CAM, Small and Medium scale enterprises (SMEs

Influence of concentration on properties of spray deposited nickel oxide films for solar cells.

Research article.Spray pyrolysis technique was used to deposit various concentration of nickel oxide films on glass substrate. The Effect of varying precursor concentration on elemental, morphological and structural properties was investigated on the deposited NiO films. Nickel (II) acetate tetrahydrate precursor was used at substrate temperature of 350 oC. Precursor concentrations were 0.025, 0.05, 0.075 and 0.1 M. Scanning Electron Microscope (SEM) surface morphology revealed nanostructured films with particles densely distributed across substrates surface. Increased in surface grains was observed as the precursor solution increased. Elemental composition of NiO films revealed presence of Ni and O element. There was reduction in oxygen concentration as precursor solution increases. Amorphous structure was observed at concentration of 0.025 M while polycrystalline with cubic structure was observed at higher concentrations. Preferred orientation was along (1 1 1) peak with small intensity along (2 0 0) peak. XRD patterns have peak diffraction at (2θ = 37 o and 43 o) for (1 1 1) and (2 0 0) planes respectively and 64 o for (2 2 0) plane for 0.1 M. Film thickness grew with increase in precursor concentration. Film micro strain was observed to have compression for all precursor solution conspicuously revealing the effect of varied concentration on NiO films propertie

Fabrication of affordable and sustainable solar cells using NiO/TiO2 P-N heterojunction.

Research article.The need for affordable, clean, efficient, and sustainable solar cells informed this study. Metal oxide TiO²/NiO heterojunction solar cells were fabricated using the spray pyrolysis technique. The optoelectronic properties of the heterojunction were determined. The fabricated solar cells exhibit a short-circuit current of 16.8 mA, open-circuit voltage of 350 mV, fill factor of 0.39, and conversion efficiency of 2.30% under 100mW/cm² illumination. This study will help advance the course for the development of low-cost, environmentally friendly, and sustainable solar cell materials from metal oxides