Luminescent Copper(I) Halides for Optoelectronic Applications

Abstract

Lead‐free copper(I) halides have been demonstrated to exhibit high photoluminescence quantum yields with high air and light stability, making them one of the most promising semiconductors for next‐generation light‐emitting diode devices. The low‐dimensional structures and soft lattices of Cu(I) halides induce the formation of self‐trapped excitons (STEs) to achieve broadband emissions with high quantum yields. Herein, the recent studies on the electronic and optical properties of Cu(I) halides (i.e., Cs3Cu2X5, CsCu2X3, and A2CuX3, where A = K+ or Rb+, X = Cl−, Br−, or I−) are reviewed and particular emphasis is placed on the role of the dimensionality and the halide in governing the electronic and optical properties (e.g., emission color and photoluminescence efficiency) via STEs. Several optoelectronic applications of Cu(I) halides are also discussed. In the last section, perspectives and challenges for the future development of Cu(I) halides in both optoelectronic and photocatalytic applications are outlined.

Lecithin Capping Ligands Enable Ultrastable Perovskite-Phase CsPbI3 Quantum Dots for Rec. 2020 Bright-Red Light-Emitting Diodes

“…There are only a few publications on bright-red LEDs based on CsPbI 3 QDs with electroluminescence wavelengths shorter than 635 nm, and the best of those reported LEDs (see Supporting Information Table T1) exhibited an external quantum efficiency (EQE) of 6.4%. , Among lead-free materials for bright-red LEDs, Sn-based perovskites display a narrow emission (FWHM 21 nm), but their devices exhibit a low EQE of 5%. − We note that both green and deep-red LEDs of lead halide perovskite QDs achieved considerable success, showcasing EQEs exceeding 20%. ,, In contrast, bright-red LEDs of CsPbI 3 QDs raise new challenges with phase degradation, spectral instability, low EQE, and poor operational stability. , …”

Light Emission of Self‐Trapped Excitons in Inorganic Metal Halides for Optoelectronic Applications

“…Their soft lattice and low‐dimensional structures lead to the formation of STEs with efficient and broadband emissions. [ 56 ]…”

One-Center and Two-Center Self-Trapped Excitons in Zero-Dimensional Hybrid Copper Halides: Tricolor Luminescence with High Quantum Yields

“…Herein, we study the photodynamics of six novel types of low-dimensional organic–inorganic hybrid copper halide compounds. The copper element has low toxicity and high abundance, and thus, the copper halides are promising optoelectronic materials. − The experiments in conjunction with density functional theory (DFT) calculations indicate that these copper halides exhibit two kinds of STE photon emission with different electron–phonon coupling strengths, temperature dependences, and lifetimes. The results reveal that they belong separately to the a-STE (localized around Cu + monomer) and m-STE (localized around Cu 2 2+ dimer), and there is phase transition between them at elevated temperatures.…”