Impact of magnetic field on photocurrent: A classical electrodynamic study, simulation, and experimental validation

Abstract

In this work, we conducted a study aimed at analyzing the impact of uniform electric and magnetic fields on the behavior of charge carriers in a solar cell, with particular focus on the evolution of the photocurrent. Relying on the classical laws of electrodynamics, formulated within a covariant framework, we established the fundamental relationship between the electric field $\overrightarrow{E}$ and the magnetic field $\overrightarrow{B}$ through the Lorentz force, without initially accounting for collisional interactions. The equations of motion of electrons and holes—describing in particular the cycloidal trajectories of carriers and the drift velocity resulting from the combined action of the two fields—constitute the theoretical basis of our analysis. The application of this formalism to the operation of a solar cell subjected to a perpendicular magnetic field reveals distinct behaviors depending on the region considered. In the depletion region, where the internal electric field is strong, the influence of the magnetic field is significant and markedly alters carrier trajectories. In contrast, in the neutral regions dominated by diffusive transport, its effect remains negligible. The results confirm that increasing the magnetic field intensity leads to a substantial reduction in the photocurrent. For instance, in a silicon solar cell with a surface area of 100 cm² under $1000W.m^{-2}$ illumination at 25 °C, MATLAB simulations indicate a decrease in photocurrent from 3.6 A to 2.6 A as the magnetic field increases from 0 to 50 mT. Experimentally, the study of a photovoltaic module with a surface area of 270 cm² under $600W.m^{-2}$ illumination shows a reduction in photocurrent from 205 to 90 mA, accompanied by an increase in series resistance from 7.76 to 17.70 Ω, under the same magnetic field variation. When the effect of collisional forces is subsequently incorporated into the modeling, the influence of the magnetic field on both series resistance and photocurrent reduction becomes even more pronounced. These findings highlight an excellent agreement between the modeling—which simultaneously accounts for electrical, magnetic, and collisional contributions—and the experimental observations, thereby validating the relevance of the proposed model and its ability to faithfully describe the behavior of solar cells in the presence of a magnetic field.