The Influence of the Solar Cell Structure and Material Composition on Its Quantum Efficiency

This study examines the influence of device architecture and substrate materials on the external quantum efficiency (EQE) of high-performance solar cells. A diverse array of photovoltaic technologies was evaluated, including formamidinium lead iodide CH5N2PbI3 (FAPI) perovskite cells and various silicon-based designs, such as Passivated Emitter and Rear Cell (PERC), Back Integrated Contact (BIC), and Bifacial structures. Quantum characteristics were determined through wavelength-dependent photocurrent measurements utilizing a precision monochromator system. Our results reveal that device structure is a primary determinant of charge carrier collection efficiency; specifically, Bifacial and PERCs achieved superior short-circuit current densities (Jsc) of 40.98 mA/cm2 and 39.42 mA/cm2, respectively. Notably, the EQE(λ) profile of Bifacial cells under n-side illumination exhibits a near-ideal rectangular shape, indicating an optimized spectral response throughout the operating spectrum. Furthermore, the analysis investigates the role of surface recombination velocity and the efficacy of advanced passivation layers—specifically Al2O3 and SiNx—in enhancing quantum performance by mitigating recombination state density. Our findings demonstrate that the strategic integration of advanced passivation layers (Al2O3 and SiNx) with optimized architectures, such as PERC and Bifacial designs, is paramount for maximizing charge carrier collection and achieving record-high current densities reaching 40.98 mA/cm2. A comprehensive analysis of solar cell performance involves spectral response (SR) and external quantum efficiency (EQE) as functions of wavelength. Additionally, SR-based current density analysis enables more accurate evaluation of cell parameters than standard I–V characterization.