Plasmon-Exciton Interaction Induced Efficient Charge Separation in Cu_2-xS-CsPbBr₃ Heterostructure

Area of Science:

• Materials Science
• Nanotechnology
• Photovoltaics

Background:

• Non-stoichiometric plasmonic semiconductors like Cu_2-xS offer tunable band gaps and NIR light harvesting for energy conversion.
• Integrating Cu_2-xS with lead halide perovskites (e.g., CsPbBr₃) creates heterostructures with strong plasmon-exciton coupling, enhancing light absorption and charge transfer.

Purpose of the Study:

• To synthesize and spectroscopically investigate non-stoichiometric Cu_2-xS, CsPbBr₃ nanocrystals (NCs), and their heterostructures.
• To understand hot carrier dynamics and extraction within the Cu_2-xS-CsPbBr₃ heterosystem using femtosecond transient absorption spectroscopy.

Main Methods:

• Synthesis of Cu_2-xS and CsPbBr₃ nanocrystals.
• Fabrication of Cu_2-xS-CsPbBr₃ heterostructures.
• Femtosecond transient absorption (TA) spectroscopy with 400 nm and 800 nm excitations.

Main Results:

• TA measurements confirmed plasmon-induced hot-hole transfer from Cu_2-xS to CsPbBr₃ valence band at both excitation wavelengths.
• 400 nm excitation additionally induced hot-electron transfer from CsPbBr₃ to Cu_2-xS conduction band.
• These synergistic charge transfer processes led to efficient charge separation and suppressed exciton recombination.

Conclusions:

• The Cu_2-xS-CsPbBr₃ heterosystem exhibits efficient charge separation and retarded exciton recombination due to synergistic charge transfer mechanisms.
• This heterosystem demonstrates significant potential for high-performance optoelectronic devices, leveraging plasmonic and perovskite properties.