S Department of Energy's National Renewable Energy Laboratory (NREL) has unveiled a new production method for a gallium arsenide (GaAs) solar cell, reaching an impressive 27% efficiency. This advancement, detailed in their recent publication in Cell Reports Physical Science, marks an important step in making solar technology both more cost-effective and efficient.
Gallium arsenide, renowned for its high electron mobility and direct band gap, has long been used in the production of single-crystalline thin-film solar cells. Yet, its widespread adoption is hindered by high manufacturing costs and the intricacies of mass production. To address these challenges, NREL has turned to dynamic hydride vapor phase epitaxy (D-HVPE) as an economical alternative to the conventional organometallic vapor phase epitaxy (OMVPE) method.
HVPE and OMVPE are two techniques used for growing crystalline layers to produce solar cells. OMVPE relies on metal-organic precursors, whereas HVPE employs hydrides, offering a quicker and more cost-effective production process.
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The research team crafted the new solar cells using an inverted configuration. They began by growing a GaAs buffer and a gallium indium arsenide phosphide (GaInAsP) etch stop layer on a GaAs substrate. Subsequently, different materials were carefully layered onto the cells' front and back contacts. The final product underwent meticulous post-processing, including the application of an anti-reflection coating.
NREL's Cell and Module Performance (CMP) Team has verified that this new cell design achieves a power conversion efficiency of more than 27%, a record for single-junction GaAs cells grown using D-HVPE. The scientists point out that their findings might also be relevant for other types of solar materials that use heterojunctions, like silicon, cadmium telluride, and perovskites.