Potassium and Rubidium Copper Halide A₂CuX₃ (A = K, Rb, X = Cl, Br) Micro- and Nanocrystals with Near Unity Quantum Yields for White Light Applications

Abstract

Lead-free ternary metal halides, especially cesium copper halides, have attracted tremendous research interest in the past two years owing to their outstanding optical properties, such as long photoluminescence (PL) decay lifetimes and high photoluminescence quantum yields (PLQYs). Recently, single crystals of potassium and rubidium copper halides have shown potential use in optoelectronics, and several synthetic methods have been reported for A 2 CuX 3 (A = K, Rb; X = Cl, Br) single crystals. Here, we have successfully synthesized A 2 CuX 3 micro-and nanocrystals by both anti-solvent recrystallization and hot injection methods, achieving size and shape control of these materials for the first time. A 2 CuX 3 micro-and nanocrystals show near-UV to deep blue emission, with emission peaks ranging from 380 to 400 nm. Emission properties included Stoke's shifts over 100 nm, a fwhm of approximately 50 nm, a long PL lifetime, and high PLQYs, in particular for K 2 CuCl 3 , which shows near unity PLQYs. In addition, these materials can be used to produce white light along with previously reported CsCu 2 I 3 nanocrystals. A mixed solution of K 2 CuCl 3 and CsCu 2 I 3 nanocrystals exhibits white light emission with a Commission Internationale de l'E ́clairage (CIE) coordinate of (0.3456, 0.3304) and a color rendering index (CRI) of 75 at a color temperature of 4855 K.

Organic–Inorganic Hybrid Cuprous‐Based Metal Halides for Warm White Light‐Emitting Diodes

“…For example, A 2 CuX 3 (A = K, Rb; X = Cl, Br), MA 4 Cu 2 Br 6 (MA = CH 3 NH 3 + ), (TBA)CuX 2 (TBA = tetrabutylammonium cation), and Cs 3 Cu 2 X 5 (X = Cl, Br, I) can be facilely prepared via solution synthesis, which show near‐UV to green emission with near‐unity PLQYs. [ 14 , 15 , 16 , 17 , 18 , 19 , 20 ] In addition to these narrowband emissions, the broadband emission which is a prerequisite for yielding warm white light can be also achieved with these Cu + ‐based compositions, such as CsCu 2 I 3 , [KC 2 ] 2 [Cu 4 I 6 ] (C = 12‐crown‐4 ether), [(C 3 H 7 ) 4 N] 2 Cu 2 I 4 , (C 16 H 36 N)CuI 2 , (Gua) 3 Cu 2 I 5 (Gua = guanidine), etc. [ 21 , 22 , 23 , 24 , 25 ] However, despite the broadband emission, very few of these materials exhibit the desirable warm white light which features CCT value of around 2700 to 4000 K. Besides, one can see that most of these Cu + ‐based broadband emissive halides are iodide compounds, which severely restricts the possible adjustment of the spectral response through halide composition.…”

Highly Resolved X‐Ray Imaging Enabled by In(I) Doped Perovskite‐Like Cs3Cu2I5 Single Crystal Scintillator

“…The scintillation light reflector was employed to avert the extra X‐ray photons noise‐point signals on the camera. [ 19 ] The imaging objects like a spring in capsule and a small electronic component are used on the undoped and 0.2% In doped Cs 3 Cu 2 I 5 SCs‐based imaging system, forming high spatial‐resolution X‐ray images in Figure 4b,c. In addition, the X‐ray images based on 0.2% In doped Cs 3 Cu 2 I 5 scintillation screen show higher sharpness than those using the undoped Cs 3 Cu 2 I 5 .…”

“…[14] Other copper halide scintillators have also been investigated, such as Rb 2 CuCl 3 , [15] CsCu 2 I 3 , [16] Cs 3 Cu 2 X 5 (X = Cl, I), and (TBA)CuX 2 (TBA = tetrabutylammonium cation; X = Cl, Br) [17] in the forms of single crystals (SCs) or polycrystalline. [18,19] However, one serious shortage for Rb 2 CuBr 3 scintillator is that the Rb element shows high natural radioactivity, which may hinder its practical application as scintillator. Other copper halides, like CsCu 2 I 3 and Rb 2 CuCl 3 , display unsatisfied LY and/or relatively low γ-ray energy resolution.…”

Highly Stable Tetrahydrothiophene 1-Oxide Caged Copper Bromide and Chloride Clusters with Deep-Red to Near-IR Emission

“…Recently, Cu­(I)-based halides have emerged as promising materials for optoelectronic applications because they tend to form low-dimensional structures with high photoluminescence quantum yield (PLQY) with low environmental impact . Ternary copper halides such as zero-dimensional (0D) Cs 3 Cu 2 X 5 (X = Cl, Br, and I) − with blue to green emission, yellow emissive one-dimensional (1D) CsCu 2 I 3 , − and deep-blue-emissive 1D A 2 CuX 3 (A = K, Rb; X = Cl, Br) − with PLQYs up to near-unity have all been reported.…”