Controlling the Anionic Ratio and Gradient in Kesterite Technology

Area of Science:

• Materials Science
• Solid-State Chemistry
• Photovoltaics

Background:

• Accurate anionic control in chalcogenide solid solutions is vital for tuning material properties.
• Compositional grading is key for band gap engineering, optimizing device interfaces, and improving solar cell performance.
• A standardized, reliable technique for anionic compositional profiling in kesterites is currently lacking.

Purpose of the Study:

• To develop a simple and innovative technique for controlling anionic composition in kesterite absorbers.
• To investigate the feasibility of achieving compositional gradients in Cu2ZnSn(S,Se)4 and Cu2ZnGe(S,Se)4 kesterites.
• To enable precise band gap grading strategies for kesterite solar cells.

Main Methods:

• A sequential deposition technique involving a pure sulfide absorber layer followed by a pure selenide layer.
• Synthesis of Cu2ZnSn(S,Se)4 and Cu2ZnGe(S,Se)4 kesterite absorbers using the developed method.
• In-depth characterization to analyze anionic redistribution and compositional profiles.

Main Results:

• Demonstrated precise control over anionic composition in Sn-based kesterites by adjusting the ratio of sulfide to selenide layer thicknesses.
• Achieved tunable anionic (Se-S) gradients in Ge-based kesterites by modifying processing conditions.
• Identified different Se incorporation dynamics for Sn- and Ge-based kesterites.

Conclusions:

• The proposed technique offers a reliable and simple approach to standardize anionic compositional profiles in kesterites.
• This method facilitates band gap grading strategies, enhancing compositional reproducibility for kesterite solar cells.
• The methodology holds potential for extension to other chalcogenide materials.