A Highly Efficient and Stable Blue‐Emitting Cs₅Cu₃Cl₆I₂ with a 1D Chain Structure

Abstract

In the field of photonics, alkali copper(I) halides attract considerable attention as lead‐free emitters. The intrinsic quantum confinement effects originating from low‐dimensional electronic structure lead to high photoluminescence quantum yields (PLQYs). Among them, Cs3Cu2I5 is the most promising candidate, satisfying both high PLQY and air stability. In this study, a strategy to explore a new material meeting these requirements through the use of the mixed‐anions of I− and Cl− is proposed. The expectation is maintained that the large difference in ionic radii between them likely results in the formation of a novel compound. Consequently, Cs5Cu3Cl6I2 with a 1D zigzag chain structure is discovered. This material exhibits blue emission (≈462 nm) with a near‐unity quantum yield of 95%. An electronic structure calculation reveals that the localized nature of the valence band maximum is crucial in obtaining efficient self‐trapped exciton emission. Moreover, the iodine‐bridged 1D connectivity significantly enhances the chemical stability of Cs5Cu3Cl6I2, compared with the pure chloride phase. The present findings provide a new perspective for developing air‐stable alkali copper(I) halides with highly efficient luminescence.

Epitaxial Growth of Lead‐Free 2D Cs3Cu2I5 Perovskites for High‐Performance UV Photodetectors

“…Such a large Stokes shift of ≈150 nm imply that the PL behavior cannot be simply attributed to the direct band emission mechanism; instead, this process may be relative to exciton self‐trapping or excited state structural reorganization. [ 50–52 ] Figure 4c reveals the temperature dependence of PL; no observable shift of the PL peak position implies a single PL mechanism for these 2D Cs 3 Cu 2 I 5 crystals. [ 53 ] The exciton binding energy could be determined by $$\[ \begin{array}{*{20}{c}}{I(T) = \frac{{{I_0}}}{{1 + A\exp \left( { - \frac{{{E_b}}}{{{k_{\rm{B}}}T}}} \right)}}}\end{array} \]$$where I(T) and I 0 are the integrated PL intensities at temperatures T and 0 K, respectively, k B is the Boltzmann constant and E b is the exciton binding energy.…”

White-light defect emission and enhanced photoluminescence efficiency in a 0D indium-based metal halide

“…1–3 Their exceptional electronic and optical properties also encourage researchers to explore potential applications beyond solar cells. 4–8 In particular, low-dimensional organic–inorganic metal halides have been considered as efficient emitters due to the merits of structural and compositional tunability, extraordinary optical properties and facile synthesis by wet and solid-state methods, 9–17 which are potentially used in display technologies, solid-state lighting, scintillators, remote thermography and anti-counterfeiting labeling. 18–25 Notwithstanding the rapid advance in materials’ diversity and photoluminescence (PL) efficiency, their fundamental photophysical mechanisms are still elusive, which needs to be clarified not only from a basic science point of view, but for the purpose of designing novel materials with exceptional PL properties for practical applications.…”

Flexible, High Scintillation Yield Cu3Cu2I5 Film Made of Ball‐Milled Powder for High Spatial Resolution X‐Ray Imaging

“…[ 12–19 ] Materials with molecular level low electronic dimensional structure like quantum well (2D), quantum wire (1D) and isolated cluster (0D) have been developed and investigated, which shown promising scintillation ability. In these materials, 0D and 1D coper hailed materials like Rb 2 CuBr 3 , [ 13 ] Rb 2 CuCl 3 , [ 18 ] CsCu 2 I 3 , [ 19 ] Cs 3 Cu 2 I 5 , [ 14,15,20 ] Cs 5 Cu 3 Cl 6 I 2 [ 21 ] demonstrate high photoluminescence quantum yield (PLQY), large light yield and large Stokes shifts, which can be attributed the self‐trapped exciton (STE) induced light emission. At the same time, they also show good stability under heat and humidity conditions, [ 22–25 ] delivering promising prototype LED device with long term stability.…”