Modifications of the CZTSe/Mo back-contact interface by plasma treatments

Area of Science:

• Materials Science
• Photovoltaics
• Thin-Film Solar Cells

Background:

• Molybdenum (Mo) is a standard back-contact material for copper zinc tin selenide (CZTSe) solar cells.
• An uncontrolled, thick molybdenum diselenide (MoSe2) interfacial layer forms during CZTSe fabrication, hindering device performance.
• Precise control over the MoSe2 layer thickness is crucial for optimizing the back-contact interface in CZTSe solar cells.

Purpose of the Study:

• To investigate the use of plasma treatments for controlling MoSe2 layer formation on Mo surfaces.
• To enhance the back-contact interface engineering in CZTSe thin-film solar cells.
• To evaluate the impact of plasma treatments on MoSe2 thickness, morphology, and subsequent solar cell performance.

Main Methods:

• As-grown Mo surfaces were treated with pure argon (Ar) plasma or mixed argon-nitrogen (Ar-N2) plasma before CZTSe absorber deposition.
• The CZTSe absorber was formed via deposition of stacked metallic layers followed by annealing in a selenium (Se) atmosphere.
• Ar plasma treatment was combined with titanium nitride (TiN) as a back-contact barrier for further analysis.

Main Results:

• Argon (Ar) plasma treatment significantly impacted MoSe2 thickness and interfacial morphology.
• Ar-N2 plasma treatment resulted in a nitrided Mo surface.
• Combining Ar plasma treatment with TiN demonstrated potential for back-contact engineering, influencing MoSe2 formation and solar cell performance.

Conclusions:

• Plasma treatments offer a viable method for controlling the MoSe2 interfacial layer in CZTSe solar cells.
• Tailoring the back-contact interface through plasma modification can lead to improved solar cell efficiency.
• This study provides insights into advanced back-contact engineering strategies for next-generation CZTSe photovoltaic devices.