International Journal of Applied Engineering Research ISSN 0973-4562 Volume 13, Number 11 (2018) pp. 9701-9705 © Research India Publications. http://www.ripublication.com 9701 Modeling of Fabricated NiO/TiO2 P-N Heterojunction Solar Cells Ukoba, O.K; and Inambao, F.L Discipline of Mechanical Engineering, University of KwaZulu-Natal, Durban, South Africa. Email :ukobaking@yahoo.com Abstract 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 o C, illumination of 1000 W/m 2 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/cm 2 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. Keyword: NiO; solar cells; modelling; simulation INTRODUCTION Despite the potential that solar energy holds for being an environmentally benign and sustainable energy source [1], large-scale production and costs still hinder the usage, especially in low-income countries [2]. This may be attributed to the difficulty in scaling up existing methods or the expense and complexities associated with vacuum environment fabrication [3]. The way forward is to develop materials and techniques that will encourage low cost or focus on a few experimental techniques [4]. The latter can be achieved with more success when combined with modelling. The modelling of result improves the planning and implementation of the experiment. Solar cells produce about 0.5 volts to 0.6 volts of open circuit voltage and 1 to 8 amps DC current depending on a range of factors but mainly related to the semiconductor used [5]. About 36 to 72 solar cells are stacked together in series to form a module which can produce meaningful output. A solar panel is an arrangement of solar modules either in series or parallel. When the solar modules are connected in parallel the currents are added while the voltage is the same, while for series the voltages are added and the current produced remains the same [6]. Solar cells can be grouped into monocrystalline, polycrystalline, and thin film technology [7]. Both monocrystalline and polycrystalline are referred to as traditional technologies of solar cells and collectively grouped as crystalline silicon. Solar cells can also be grouped by generations of the solar cells [8, 9]. The traditional technologies of solar cell manufacture use microelectronic manufacturing with an efficiency ranging from 10 % to 15 % and 9 % to 12 % for monocrystalline and polycrystalline respectively. Thin films’ efficiency varies depending on the fabrication techniques and materials used. The monocrystalline solar cells tend to have the highest efficiency and are also very expensive. Metal oxide heterojunction solar cells are currently attracting attention due to their potential [10]. Metal oxides offer great promise for being a solution to affordable, environmentally friendly, sustainable and viable energy, so ending the world energy problem, especially in developing and low-income countries [11, 12]. Metal oxides, especially NiO thin film, are the most promising materials to be used as solar cell absorber layers due to their excellent optical properties They have good band gaps, low cost and great absorption coefficients as well as constituents that are nontoxic and abundant naturally [13]. However, most of them still exhibit weak conversion efficiencies resulting in several experiments in the laboratory in an attempt to obtain the optimum power conversion efficiency with current levels being about 8.4 % [14] compared to those of other technological paths in the photovoltaic field like CIGS-based solar cells which reach record efficiencies of over 20 % [10]. However, despite the development of several physical and chemical fabrication techniques for PV [15-17], several reasons could explain this situation, such as various loss mechanisms due to absorber features. Modelling has been used in other fields to reduce the amount of person-hours and resources spent performing experiments [18]. Modelling of solar energy spans many decades, with most models focusing on photovoltaic panels and modules. The few studies on solar cells are mainly on silicon and related solar cells [19-21]. There is, therefore, a need to explore ways of modelling metal oxide cells due to the increasing interest in them. This study attempts to model metal oxides heterojunctions (NiO/TiO2) using modelling tools (including SCAPS) which were successfully deployed in previous generations of solar cell research. SCAPs stands for Solar Cell Capacitance Simulator and is used for one or two-dimensional solar cell simulation. Therefore, a detailed analysis of the effect of deposition temperature, thickness, and defects densities of a NiO layer is necessary and has been presented in this work using the numerical simulation package SCAPS [22]. The results proposed in this study are a useful guideline for design of high performances NiO based solar cells.