Bulk and interface engineering of 1.7 eV-bandgap chalcogenide solar cells enabling record efficiency

Area of Science:

• Materials Science
• Renewable Energy
• Semiconductor Physics

Background:

• Wide-bandgap chalcogenide photovoltaics are promising for tandem solar cells and water splitting.
• Performance is hindered by interfacial and bulk defects in these materials.

Purpose of the Study:

• To enhance efficiency in 1.7-electron volt copper gallium selenide (CuGaSe2) thin-film solar cells.
• To investigate the effects of aluminum (Al) alloying and rubidium (Rb) incorporation on CuGaSe2 properties.

Main Methods:

• Alloying CuGaSe2 with Al and incorporating Rb.
• Engineering a back-surface electric field using a steep Al concentration gradient.
• Characterizing interfacial chemistry, structural properties, and defect behavior.

Main Results:

• Al- and Rb-modified CuGaSe2 showed distinct interfacial chemistry and defect behavior.
• A steep Al gradient effectively boosted device performance, even at low Al concentrations.
• Achieved higher open-circuit voltage without compromising photovoltaic efficiency.

Conclusions:

• Aluminum alloying and rubidium incorporation establish a new performance benchmark for wide-bandgap chalcogenides (1.65-1.75 eV).
• These strategies offer a promising pathway for developing next-generation, high-efficiency photovoltaic technologies.