OICC Press Majlesi Journal of Electrical Engineering 2345-3796 19 4 2025 12 25 Modeling and Bandgap Optimization of Multijunction Solar Cells for High-Efficiency Photovoltaic Performance 10.57647/j.mjee.2025.17740 EN Muhammad Aliff Hafeez Bin Azman Faculty of Electrical and Electronic Engineering, University Tun Hussein Onn Malaysia, Johor, Malaysia Sim Yi Sy Yi Faculty of Electrical and Electronic Engineering, University Tun Hussein Onn Malaysia, Johor, Malaysia https://orcid.org/0000-0002-1833-1188 Kah Haw Law Electrical and Electronic Engineering Programme Area, Universiti Teknologi Brunei, Bandar Seri Begawan BE1410, Brunei Mohd Abdul Talib Mat Yusoh School of Electrical Engineering, College of Engineering, Universiti Teknologi MARA, Shah Alam Selangor, Malaysia https://orcid.org/0000-0002-4503-826X Md Nor Ramdon Bin Baharom Faculty of Engineering Technology, University Tun Hussein Onn Malaysia, Johor, Malaysia Alvin John Lim Meng Siang Faculty of Civil Engineering and Built Environment, Universiti Tun Hussein Onn Malaysia, Johor, Malaysia Nur Sabrina Binti Azli Murzami Founder Energy Sdn Bhd, Klang, Selangor, Malaysia Khalid Aboubakr Hasan Mousay Technical College of Civil Aviation and Meteorology Esbea, Libya https://orcid.org/0009-0007-0102-2403 Journal Article 2025 12 25 Global energy use is rising yearly, resulting in a higher demand. Power plants must generate more electricity,  thereby placing significant stress on the electrical grid. Solar engineering is a promising solution to this challenge. However, traditional silicon-based solar cells face inherent limitations. These cells rely on a single material, which restricts their power conversion efficiency by only capturing a very specific range of the sunlight spectrum.This study explores a novel concept in solar cell design that utilizes a multijunction approach, employing various semiconductor materials to create multiple p-n junctions within the cells. By strategically arranging these materials according to their energy bandgaps, the aim is to maximize the capture of the sunlight spectrum for enhanced power conversion and energy output, ultimately improving efficiency. The research was conducted using MATLAB software to focus on mathematical modeling. By analyzing designs from single junctions up to quintuple junctions and utilizing materials such as Germanium Sulfide, Gallium Arsenide, and Germanium, the study revealed that increasing the number of material layers significantly enhanced the performance of the solar cells. Notably, the quintuple junction solar cell demonstrated the highest efficiency, achieving 26.87% more efficiency compared to single junction cells, which recorded an efficiency of 42.63%.