Optimization of the conversion efficiency of a vertical junction silicon solar cell: Role of spectrum and recombination

This study focuses on optimizing the conversion efficiency of a vertical-junction silicon photovoltaic cell by analyzing the combined influence of the incident light spectrum and recombination mechanisms. A theoretical model incorporating depth- and wavelength-dependent photogeneration, surface reflectance, and bulk and surface recombination was developed.

The results show that:

• Carrier generation strongly depends on both wavelength and depth, highlighting the importance of effective surface passivation and appropriate cell thickness;

• The external quantum efficiency (EQE) reveals the effective spectral regions and emphasizes losses due to recombination and reflectance;

• The overall efficiency under the AM1.5 spectrum saturates at optimal thicknesses, confirming the trade-off between absorption and thickness;

• Surface recombination is a critical parameter: reducing the effective surface recombination velocity Seff is essential to maximize the short-circuit current Jsc and efficiency η;

• Depth-wavelength mapping and optimization strategies provide practical guidelines for designing high-performance cells by combining thickness, spectrum, and passivation.

These results demonstrate that the simultaneous management of optical and electronic losses is key to approaching the theoretical performance limits of silicon, and they open perspectives for the integration of selective antireflective coatings, improved surface passivation, and controlled bulk and surface recombination.