Modulating Band Offset through Interface Engineering of Cu₂SnSe₃-Based Heterojunctions for Efficient Charge...

Area of Science:

• Materials Science
• Nanotechnology
• Renewable Energy

Background:

• Copper tin selenide (Cu₂SnSe₃) is a promising solar absorber material with broad solar absorption and tunable band gap.
• Low efficiency in Cu₂SnSe₃-based solar cells is often attributed to interface recombination and poor crystallinity.

Purpose of the Study:

• To develop a facile synthesis method for Cu₂SnSe₃ nanoparticles (NPs).
• To investigate the structural, optoelectronic, and band alignment properties of Cu₂SnSe₃ NPs for solar absorber applications.
• To explore interface engineering strategies using n-type CdSe and ZnSe NPs to improve solar cell performance.

Main Methods:

• Facile synthesis of Cu₂SnSe₃ nanoparticles.
• Experimental characterization including cyclic voltammetry (CV) and UV photoelectron spectroscopy (UPS).
• Theoretical calculations using density functional theory (DFT) for band alignment analysis.

Main Results:

• A staggered type-II band alignment was observed at the Cu₂SnSe₃/CdSe heterojunction with a minimal conduction band offset (0.06 eV).
• Cyclic voltammetry, UPS, and DFT calculations indicated effective charge carrier separation and transport at the interface.
• The Cu₂SnSe₃/CdSe heterojunction exhibited Schottky I-V characteristics with a dark current of 1 mA.

Conclusions:

• The developed synthesis method yields Cu₂SnSe₃ NPs suitable for solar absorber applications.
• Interface engineering with CdSe effectively modulates band offsets and promotes charge carrier separation.
• Cu₂SnSe₃ NPs show significant potential for efficient thin-film solar cells by mitigating interface recombination losses.