Researchers at the U.S. Department of Energy’s (DOE) National Renewable Energy Laboratory (NREL) have published a study that reveals how sound waves could play a pivotal role in making solar cells more affordable for earth-bound applications.

The team said III-V solar cells are a type of solar cell technology with exceptional efficiency, named after the elements from groups III and V of the periodic table used in their fabrication.

However, the high cost associated with manufacturing III-V solar cells has confined their use mainly to space applications, powering satellites, and spacecraft.

The new research introduces a novel manufacturing process called acoustic spalling, which can potentially reduce the cost of producing highly efficient III-V solar cells.

Unlike existing methods that use a sacrificial etch layer to lift off the solar cell from the gallium arsenide (GaAs) substrate, acoustic spalling enables a controlled fracture within the substrate nearly parallel to its surface.

This fracture allows for the easy removal of the cell without leaving any residue, resulting in a contaminant-free surface that eliminates the need for expensive polishing.

The process’s speed is one of its key advantages. While the existing method takes hours, acoustic spalling takes seconds to create the fracture, making it efficient and cost-effective.

The technique has been designed to minimize the formation of large facets on the substrate. The result is a smoother surface that can be readily used to grow a new solar cell with minimal or no surface repreparation.

Substrate Reuse and Cost Reduction

The potential for substrate reuse is the most promising aspect of acoustic spalling. By enabling the repeated use of substrates, the cost associated with manufacturing III-V solar cells can be substantially reduced.

Kevin Schulte, a scientist in NREL’s High-Efficiency Crystalline PV group and the lead author of the research article, emphasizes that while acoustic spalling alone may not make III-V solar cells entirely cost-effective, it is part of a comprehensive research portfolio aimed at addressing cost from multiple angles.

The technology behind acoustic spalling was developed at Arizona State University and is being commercialized by Crystal Sonic Inc, a Phoenix-based company.

The NREL-certified efficiency of a cell manufactured on a previously spalled substrate reached 26.9%, comparable to what can be achieved with a brand-new substrate.

Recently a team of researchers from the Georgia Institute of Technology took a novel approach, utilizing aluminum foil to create solid-state batteries with increased energy density and stability compared to the widely used lithium-ion technology.

Researchers at the Massachusetts Institute of Technology developed a new battery made from aluminum and sulfur, two of the nature-abundant and cost-friendly materials.