Structural Modulation Enables Bright and Efficient Cs-Cu-Cl Electroluminescence.

Area of Science:

• Materials Science
• Solid-State Physics
• Optoelectronics

Background:

• Cesium-copper-halide (Cs-Cu-X) perovskites are explored as non-toxic alternatives to lead-halide perovskites for white light-emitting diodes (LEDs).
• These materials exhibit unique self-trapped exciton (STE) properties beneficial for broadband electroluminescence (EL).
• Previous research focused on Cs-Cu-I systems, with no reported EL from Cs-Cu-Cl counterparts.

Purpose of the Study:

• To demonstrate electroluminescence (EL) in cesium-copper-chloride (Cs-Cu-Cl) nanocrystals (NCs).
• To investigate the factors contributing to efficient bluish-white EL in Cs-Cu-Cl NCs.
• To expand the family of copper-based perovskite light-emitting devices for display and lighting applications.

Main Methods:

• Holistic structural modulation of Cs-Cu-Cl nanocrystals.
• Fabrication and characterization of Cs-Cu-Cl nanocrystal-based LEDs.
• Analysis of film morphology, exciton inter-band transitions, triplet STE behavior, and electron transport properties.

Main Results:

• Successful demonstration of electroluminescence (EL) in Cs-Cu-Cl nanocrystals for the first time.
• The champion device achieved an external quantum efficiency (EQE) of 2.02% and a luminance of 3345 cd m⁻².
• Efficient bluish-white EL was attributed to smooth film morphology, exciton inter-band transition, triplet STE behavior, and good electron transport.

Conclusions:

• Cs-Cu-Cl nanocrystals are a viable material for efficient broadband electroluminescence.
• The study provides insights into the photophysical processes governing the emission in Cs-Cu-Cl NCs.
• This work broadens the scope of copper-based perovskites for next-generation lighting and display technologies.