Near-Unity Photoluminescence Quantum Yield in Blue-Emitting Cs₃Cu₂Br_5–xI_x (0 ≤ x ≤ 5)

Abstract

Recently, interest in developing efficient, low-cost, nontoxic, and stable metal halide emitters that can be incorporated into solid-state lighting technologies has taken hold. Here we report nontoxic, stable, and highly efficient blue-light-emitting Cs3Cu2Br5–x I x (0 ≤ x ≤ 5). Room-temperature photoluminescence measurements show bright blue emission in the 456 to 443 nm range with near-unity quantum yield for Cs3Cu2I5. Density functional theory calculations and power-dependent PL measurements suggest that the emission results from self-trapped excitons induced by strong charge localization within the zero-dimensional cluster structure of Cs3Cu2Br5–x I x .

Rb2CuX3 (X = Cl, Br): 1D All‐Inorganic Copper Halides with Ultrabright Blue Emission and Up‐Conversion Photoluminescence

“…The presence of monovalent Cu + cations in these materials and their ionic nature makes them susceptible to degradation in ambient air (Figures S4–S6, see Supporting Information for further details) However, larger single crystals of Rb 2 CuCl 3 do not exhibit any noticeable degradation when left in ambient air (Figure S6, Supporting Information). On the other hand, our thermogravimetric analysis (TGA) measurements suggest that unlike most hybrid organic–inorganic lead halide perovskites, Rb 2 CuX 3 show no significant weight loss up to 475 °C (Figure S7, Supporting Information), which is in agreement with the reports of improved thermal stability of all‐inorganic metal halides such as Cs 3 Cu 2 Br 5− x I x ,7a Rb 4 Ag 2 BiBr 9 , and Cs 2 SnI 6 . Differential scanning calorimetry (DSC) data show that Rb 2 CuCl 3 and Rb 2 CuBr 3 have peritectic decompositions at 274 and 271 °C, respectively, consistent with the reported phase diagrams …”

“…Despite the remarkable progress in the last few years, these deep blue emitters are predominantly low‐dimensional or nanostructured lead halide perovskites, which usually suffer from the lead toxicity and poor stability . In principle, other Pb‐free low‐dimensional halides should also demonstrate increased charge localization and enhanced excitonic properties observed in lead halide perovskites, yielding efficient blue emitters that are free of toxic Pb such as in the case of recently reported copper halides Cs 3 Cu 2 X 5 and CsCu 2 X 3 . In this work, we provide further evidence of the validity of this conjecture through preparation of all‐inorganic nontoxic Rb 2 CuX 3 (X = Cl and Br), which exhibit near‐unity PLQY blue emission.…”

All‐Inorganic CsCu2I3 Single Crystal with High‐PLQY (≈15.7%) Intrinsic White‐Light Emission via Strongly Localized 1D Excitonic Recombination

“…The exciton binding energy obtained by fitting: E b = 346 ± 14 meV (Figure 3c) is much larger than that in the traditional 3D inorganic material. [10,27] This large phononelectron interaction indicates that exciton localization is closely related to lattice vibration. The relationship between FWHM and temperature (Figure 3d) can be extracted to obtain the interaction between phonon and electron: ℏω = 19.84 ± 0.21 meV.…”

Neoteric Mn2+‐activated Cs3Cu2I5 dazzling yellow‐emitting phosphors for white‐LED

“…At present, the lead halide perovskite with the expression of CsPbX 3 (X = Cl, Br, I) has gained considerable importance because of their splendid optical performance . With the introduction of Mn 2+ ions, some impressive emissions were detected in the CsPbX 3 system . Nevertheless, these CsPbX 3 lead halide perovskites suffer from complex preparation process and high toxicity, hindering their further applications.…”

“…17,18 With the introduction of Mn 2+ ions, some impressive emissions were detected in the CsPbX 3 system. 19,20 Nevertheless, these CsPbX 3 lead halide perovskites suffer from complex preparation process and high toxicity, hindering their further applications. Thus, a substitutive lead-free halide should be developed to figure out this issue.…”