Zero-Dimensional Broadband Yellow Light Emitter (TMS)₃Cu₂I₅ for Latent Fingerprint Detection and Solid-State Lighting

Area of Science:

• Materials Science
• Inorganic Chemistry
• Photophysics

Background:

• Copper(I) halides are explored for light-emitting applications but often suffer from instability, particularly blue emitters.
• Hybrid organic-inorganic materials offer potential for enhanced stability and tunable optoelectronic properties.

Purpose of the Study:

• To synthesize and characterize a new hybrid organic-inorganic copper(I) halide with efficient and stable light emission.
• To investigate the structure-property relationships governing the luminescence of this new material.
• To demonstrate the practical applicability of the synthesized compound in devices and security applications.

Main Methods:

• Synthesis of the hybrid compound (TMS)3Cu2I5.
• Crystal structure determination using X-ray diffraction.
• Photoluminescence quantum yield (PLQY) measurements.
• Fabrication and testing of white light-emitting diodes (WLEDs).
• Evaluation as a luminescent agent for latent fingerprint visualization.

Main Results:

• A new hybrid organic-inorganic Cu(I) halide, (TMS)3Cu2I5, was synthesized, exhibiting stable yellow light emission with a PLQY > 25%.
• The zero-dimensional crystal structure features isolated [Cu2I5]3- dimers, promoting quantum confinement and efficient emission from self-trapped excitons.
• In contrast, substitution with Ag resulted in (TMS)AgI2 with a 1D chain structure and weak emission.
• (TMS)3Cu2I5 was successfully used in a WLED with a high Color Rendering Index (82) and for latent fingerprint imaging.

Conclusions:

• The hybrid structure of (TMS)3Cu2I5 provides enhanced stability and efficient nonblue emission, overcoming limitations of inorganic copper halides.
• This material is a promising candidate for practical optoelectronic applications, including lighting and security.
• The study opens new avenues for designing multifunctional, non-toxic hybrid metal halides.