In Situ Vanadium Modification Induced a Back Interfacial Field Passivation Effect toward Efficient Kesterite Solar...

Area of Science:

• Materials Science
• Renewable Energy
• Semiconductor Physics

Background:

• High-quality back electrode interfaces (BEI) are essential for efficient copper zinc tin sulfide selenide (CZTSSe) solar cells, requiring suppressed recombination.
• Traditional chemical passivation is common, but field passivation effects (FPE) at the BEI remain underexplored.

Purpose of the Study:

• To introduce and investigate an in situ field passivation effect (FPE) at the BEI of CZTSSe solar cells.
• To enhance the performance of CZTSSe solar cells by optimizing the BEI through FPE.

Main Methods:

• Vanadium (V) was in situ incorporated into the MoSe₂ interfacial layer during Mo:V electrode deposition and selenization.
• A p-type MoSe₂:V layer was formed, creating a p-MoSe₂:V/p-CZTSSe interface with an optimized band alignment.
• Fermi energy level shifts were analyzed to understand the passivation mechanism.

Main Results:

• An in situ VI-FPE interface was successfully established at the BEI.
• The incorporation of V into MoSe₂ created a p-type layer (MoSe₂:V) with a downward Fermi energy level shift of 0.62 eV.
• CZTSSe solar cells with the FPE (cell-FPE) showed significantly improved photovoltaic parameters compared to reference cells (cell-ref).

Conclusions:

• The developed in situ VI-FPE effectively suppresses recombination and enhances carrier transport at the BEI.
• The optimized band alignment and improved carrier dynamics led to a substantial increase in CZTSSe solar cell efficiency from 8.28% to 11.11%.
• This work demonstrates a promising strategy for improving CZTSSe solar cell performance through engineered BEI using field passivation.