Efficient and Stable Deep-Blue 0D Copper-Based Halide TEA₂Cu₂I₄ with Near-Unity Photoluminescence Quantum Yield for...

Area of Science:

• Materials Science
• Solid-State Chemistry
• Photophysics

Background:

• Achieving saturated deep-blue emission is crucial for white LED technology.
• Existing materials often face challenges with efficiency, toxicity, or stability.
• Novel luminescent materials are needed to overcome these limitations.

Purpose of the Study:

• To synthesize and characterize a new deep-blue emitting material.
• To investigate its photophysical properties and structural characteristics.
• To evaluate its potential for optoelectronic applications.

Main Methods:

• Synthesis of [N(C₂H₅)₄]₂Cu₂I₄ (TEA₂Cu₂I₄) single crystals and polycrystalline films.
• Photoluminescence (PL) and time-resolved photoluminescence (TRPL) spectroscopy.
• Temperature-dependent PL measurements.
• Density functional theory (DFT) calculations.
• Stability testing under UV irradiation and ambient conditions.
• Fabrication of an electroluminescent device.

Main Results:

• TEA₂Cu₂I₄ exhibits deep-blue photoluminescence at 450 nm with a high PLQY (96.7% for SCs, 87.2% for films).
• The material shows a large Stokes shift (180 nm), long lifetime (1.7 μs), and phosphorescent characteristics.
• TEA₂Cu₂I₄ demonstrates excellent stability, with minimal degradation after UV exposure and long-term ambient storage.
• An electroluminescent device fabricated with TEA₂Cu₂I₄ thin film emitted saturated deep-blue light (CIE: 0.143, 0.076).

Conclusions:

• The zero-dimensional structure of TEA₂Cu₂I₄, with [Cu₂I₄]²⁻ units spaced by [N(C₂H₅)₄]⁺ cations, enables efficient deep-blue emission.
• TEA₂Cu₂I₄ possesses outstanding photophysical properties and stability, making it a promising candidate for optoelectronics.
• This material addresses the critical need for stable, efficient deep-blue emitters in LED technology.