Integration of Si Heterojunction Solar Cells with III-V Solar Cells by the Pd Nanoparticle Array-Mediated "Smart...

Area of Science:

• Materials Science
• Renewable Energy
• Semiconductor Physics

Background:

• Tandem solar cells offer higher efficiencies by stacking multiple junctions.
• Silicon heterojunction (SHJ) and III-V cells are promising for tandem applications.
• Directly connecting dissimilar cells via nanoparticle arrays can face challenges like poor electrical contact and passivation degradation.

Purpose of the Study:

• To develop an effective method for fabricating two-terminal tandem solar cells using SHJ bottom cells and III-V top cells.
• To overcome performance limitations associated with direct nanoparticle integration on SHJ cells.
• To enhance electrical contacts and preserve passivation quality in SHJ cells for improved tandem performance.

Main Methods:

• Fabrication of two-terminal tandem solar cells using a "smart stack" approach with palladium nanoparticle (NP) arrays.
• Introduction of hydrogenated nanocrystalline silicon (nc-Si:H) layers between Pd NPs and SHJ cells.
• Integration of nc-Si:H-capped SHJ cells with InGaP/AlGaAs double-junction cells.

Main Results:

• Achieved a certified power conversion efficiency of 27.4% under AM 1.5 G illumination.
• Demonstrated that nc-Si:H layers improve electrical contacts and maintain passivation quality of SHJ cells.
• Identified an interfacial gap at the smart stack interface as a limiting factor for current density and efficiency.

Conclusions:

• The developed nc-Si:H-capped SHJ solar cells integrated with III-V top cells show significant potential for high-efficiency tandem devices.
• Reducing the interfacial gap distance, controlled by Pd NP height, is crucial for further efficiency improvements.
• The "smart stack" approach with optimized interfacial layers is a viable strategy for advanced tandem solar cell fabrication.