CuI as a Hole-Selective Contact for GaAs Solar Cells

Area of Science:

• Materials Science
• Semiconductor Physics
• Renewable Energy

Background:

• Carrier-selective contacts are crucial for advanced solar cell designs.
• III-V semiconductors offer high performance but face fabrication challenges.

Purpose of the Study:

• To demonstrate the first hole-selective III-V semiconductor solar cell using copper iodide (CuI) on intrinsic gallium arsenide (i-GaAs).
• To investigate the impact of surface passivation and CuI composition on solar cell performance.

Main Methods:

• Fabrication of a solar cell using CuI on i-GaAs with varying InGaP passivation layers.
• Characterization using photoluminescence, energy-dispersive X-ray, and ultraviolet photoelectron spectroscopy.
• Optimization of CuI by atmospheric oxidation to increase oxygen content.

Main Results:

• Achieved over 300 mV improvement in open-circuit voltage (VOC) with optimized InGaP passivation.
• Demonstrated that oxygen incorporation in CuI enhances hole selectivity and solar conversion efficiency.
• Reached a VOC of nearly 1 V and a solar conversion efficiency of 13.4% with optimized fabrication.

Conclusions:

• The developed solar cell architecture enables fully carrier-selective devices with reduced fabrication complexity.
• The use of non-epitaxial CuI and undoped GaAs is compatible with low-cost crystal growth methods.
• This work significantly impacts III-V solar cell fabrication, offering a pathway to lower costs and improved performance.