Influence of Base Depth on the Frequency-Dependent Impedance Characteristics of Vertical Silicon Solar Cells Using Dynamic Impedance Spectroscopy

Abstract

This theoretical study investigates the frequency-dependent impedance behavior of vertical parallel-junction silicon (Si) solar cells, focusing on the impact of base depth under modulated illumination. Using dynamic impedance spectroscopy (DIS) and analyzing Bode and Nyquist diagrams, key electrical parameters, including series and parallel resistances, capacitance, and inductance, are extracted. The results reveal that increasing the base depth leads to a decrease in both the real and imaginary components of capacitance, a reduction in parallel resistance, and a transition from predominantly capacitive to more inductive behavior. The impedance spectra show a quarter-circle arc at low frequencies and a near-linear response at high frequencies, reflecting changes in dominant charge transport and recombination mechanisms. The cutoff frequency decreases significantly with depth, highlighting spatial limitations in minority carrier generation. These findings emphasize the critical role of base depth in shaping the solar cell’s internal electrical characteristics and validate IS as a powerful tool for optimizing device design, absorber thickness, and equivalent circuit modeling in high-efficiency photovoltaic (PV) systems.