AC BACK SURFACE RECOMBINATION VELOCITY AND OPTIMUM BASE THICKNESS IN AN IRRADIATED N+-P-P+ SILICON SOLAR CELL UNDER TEMPERATURE AND FREQUENCY MODULATION

This work presents a theoretical study of an irradiated n+-p-p bifacial silicon solar cell under AC polychromatic illumination and temperature variation, with the aim of determining the optimum base thickness using the back surface recombination velocity approach. The analysis is based on the resolution of the continuity equation of minority carriers in the base under frequency modulation, taking into account the combined effects of irradiation energy flux, damage coefficient, temperature, and modulation frequency. Analytical expressions of the two components of the back surface recombination velocity, Sb1 and Sb2, are derived from the AC photocurrent density. The optimum base thickness is determined from the intersection of Sb1 and Sb2 profiles as a function of base thickness. Numerical results show that the optimum thickness strongly depends on modulation frequency, temperature, irradiation energy, and damage coefficient through their influence on the minority carrier diffusion coefficient and diffusion length. The optimum thickness decreases with increasing irradiation level and damage coefficient due to enhanced recombination effects, while temperature and frequency significantly modify carrier transport properties. This approach provides a reliable method for optimizing silicon solar cell base thickness under combined environmental and irradiation effects, contributing to the improvement of photovoltaic device performance.