Perovskite/CIGS Spectral Splitting Double Junction Solar Cell with 28% Power Conversion Efficiency

Area of Science:

• Materials Science
• Renewable Energy
• Photovoltaics

Background:

• Theoretical efficiency of double-junction solar cells is maximized with a bottom cell bandgap around 0.9-1.0 eV, lower than silicon (1.1 eV).
• Copper indium gallium selenide sulfide (CIGS) solar cells offer tunable bandgaps based on composition and depth profiling.

Purpose of the Study:

• To experimentally validate the effect of using lower bandgap CIGS solar cells as the bottom cell in a two-junction configuration.
• To demonstrate the performance of a perovskite/CIGS tandem solar cell.

Main Methods:

• Preparation of various CIGS solar cells with bandgaps from 1.02 to 1.14 eV.
• Fabrication of a four-terminal tandem cell using a mixed-halide perovskite top cell (1.59 eV) and a CIGS bottom cell (1.02 eV).
• Utilized a 775-nm spectral splitting mirror for tandem configuration.

Main Results:

• The perovskite/CIGS tandem solar cell achieved a power conversion efficiency of 28.0% at a 1 cm² aperture area.
• The stand-alone efficiencies of the top perovskite cell were 21.0% and the bottom CIGS cell were 21.5%.

Conclusions:

• Demonstrated the effectiveness of employing lower bandgap CIGS solar cells in tandem architectures.
• Achieved high efficiency in a perovskite/CIGS tandem solar cell, highlighting its potential for advanced photovoltaic applications.