Post passivation light trapping back contacts for silicon heterojunction solar cells

Area of Science:

• Materials Science
• Renewable Energy Engineering
• Photovoltaics

Background:

• Light trapping is crucial for high-efficiency crystalline silicon (c-Si) solar cells, aiming for reduced material usage and cost.
• Current methods for enhancing light trapping often compromise electrical properties.

Purpose of the Study:

• To implement and evaluate highly efficient light-trapping back contacts for silicon heterojunction solar cells.
• To decouple optically active and electrically active layers for improved performance.

Main Methods:

• Texturing an amorphous silicon layer with a refractive index similar to c-Si at the back of the wafer.
• Applying various light-trapping textures to prototype silicon heterojunction solar cells.
• Utilizing randomly distributed craters as the most effective light-trapping texture.

Main Results:

• Achieved significant path length enhancement factors with high passivation quality.
• Enhanced short-circuit current density (JSC) by approximately 1.8 mA cm⁻² to 38.5 mA cm⁻² in the 1000-1150 nm wavelength range.
• Demonstrated improved performance compared to a planar reference solar cell.

Conclusions:

• The developed light-trapping back contact concept successfully improves light absorption in c-Si solar cells.
• This approach offers potential for enhancing monolithic Si multijunction solar cells and other configurations.
• Decoupling optical and electrical layers through advanced texturing is a promising strategy for future solar cell designs.