First-Principles Study of Radiation-Induced Defects in Silicon Solar Cells Using Density-Functional Theory Simulation

Displacement damage from high-energy electron and proton irradiation is a critical degradation mechanism in space solar cells, particularly within the Van Allen radiation belts. These energetic particles induce atomic displacements in semiconductor materials, generating lattice defects such as vacancies, di-vacancies, and impurity-related complexes (e.g., BiOi, BiCs and BiHi) that significantly impact the electronic structure of silicon, reducing solar cell efficiency and power output. A fundamental understanding of these defects is critical for designing radiation-resistant photovoltaics. To address this challenge, we employ first-principles Density Functional Theory(DFT) using the SIESTA code with localized orbital basis sets to model the electronic structure of silicon systems with induced defects and impurities. Our study focuses on boron-related defect complexes, including interstitial boron (Bi) and its interactions with oxygen (O) and hydrogen (H), with validation against experimental data and comparative calculations using QUANTUM-ESPRESSO to assess computational robustness. Our simulation identifies key defect energy levels, including BiOi at Ec – 0.23 eV and BiCs at Ev + 0.31 eV, which exhibit strong agreement with experimental data, reinforcing the reliability of our approach. We further analyze the passivating role of interstitial hydrogen (Hi) and its influence on defect neutralization. These findings provide critical insights for defect engineering strategies, enabling optimized doping and thermal processing to mitigate radiation-induced degradation. This research advances the development of next-generation, radiation-tolerant photovoltaics for prolonged space missions by identifying dominant defect configurations and their electronic structure.