Doped Zero-Dimensional Cesium Zinc Halides for High-Efficiency Blue Light Emission

Area of Science:

• Materials Science
• Solid-State Chemistry
• Photophysics

Background:

• All-inorganic zero-dimensional (0D) metal halides are gaining attention for their photoluminescence (PL) properties and stability.
• Cesium zinc bromide (Cs2ZnBr4) is a promising 0D material, but its intrinsic luminescence is weak.

Purpose of the Study:

• To investigate the effect of copper(I) doping on the photoluminescence of 0D Cs2ZnBr4.
• To explore the origin of the enhanced blue emission in copper-doped Cs2ZnBr4.
• To evaluate the potential of other A-site cations and halogens in copper-doped 0D metal halides for blue emission.

Main Methods:

• Synthesis of copper(I)-doped Cs2ZnBr4 and related compounds (Cs2ZnCl4:Cu, Rb2ZnCl4:Cu).
• Photoluminescence (PL) spectroscopy to characterize emission properties.
• Ultrafast transient absorption (TA) spectroscopy to study excited-state dynamics.
• Photoluminescence quantum yield (PLQY) measurements.

Main Results:

• Copper(I) doping into Cs2ZnBr4 resulted in efficient blue emission centered at 465 nm with a PLQY of 65.3%.
• Ultrafast transient absorption studies provided insights into the mechanism of blue emission.
• Synthesized A2ZnCl4:Cu (A=Cs, Rb) exhibited intense sky-blue emission with a PLQY of approximately 73.1%.

Conclusions:

• Copper(I) doping is an effective strategy to enhance the blue emission of 0D Cs2ZnBr4.
• The developed materials are environmentally friendly, low-cost, and exhibit high efficiency for blue light emission.
• This research offers a pathway for developing novel blue-emitting 0D all-inorganic metal halides.