Near-Unity Photoluminescence Quantum Yield in Blue-Emitting Cs₃Cu₂Br_5–<i>x</i>I_<i>x</i> (0 ≤ <i>x</i> ≤ 5)

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–xIx (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–xIx

Hybrid Organic–Inorganic Halides (C₅H₇N₂)₂MBr₄ (M = Hg, Zn) with High Color Rendering Index and High-Efficiency White-Light Emission

Low-dimensional hybrid organic–inorganic materials (HOIMs) are being widely investigated for their unique optoelectronic properties. Some of them exhibit broadband white-light (WL) luminescence upon UV excitation, providing a potential for the fabrication of single-component white-light-emitting diodes. Here, we report new examples of low-dimensional HOIMs, based on 4-aminopyridinium (4AMP) and group 12 metals (Hg and Zn), for single-component WL emission. The 4AMP cation containing structures feature HgBr4 and ZnBr4 isolated tetrahedra in (C5H7N2)2HgBr4·H2O (1) and (C5H7N2)2ZnBr4 (2), respectively. The presence of isolated molecular units in the zero-dimensional structures results in strongly localized charges and bright WL luminescence with corresponding Commission Internationale de l’Eclairage color coordinates of (0.34, 0.38) and (0.25, 0.26), correlated color temperatures of 5206 K (1) and 11 630 K (2), and very high color rendering indexes (CRI) of 87 (1) and 96 (2). The visibly bright WL emission at room temperature is corroborated with high measured photoluminescence quantum yield values of 14.87 and 19.18% for 1 and 2, respectively. Notably, the high CRI values for these new HOIMs exceed the commercial requirements and produce both “warm” and “cold” WL depending on the metal used (Hg or Zn). Based on temperature- and powder-dependent photoluminescence (PL), PL lifetimes measurements and density functional theory calculations, the broadband WL emission is assigned to the 4AMP organic molecules emission and self-trapped states

Hybrid Organic–Inorganic Halides (C₅H₇N₂)₂MBr₄ (M = Hg, Zn) with High Color Rendering Index and High-Efficiency White-Light Emission

Low-dimensional hybrid organic–inorganic materials (HOIMs) are being widely investigated for their unique optoelectronic properties. Some of them exhibit broadband white-light (WL) luminescence upon UV excitation, providing a potential for the fabrication of single-component white-light-emitting diodes. Here, we report new examples of low-dimensional HOIMs, based on 4-aminopyridinium (4AMP) and group 12 metals (Hg and Zn), for single-component WL emission. The 4AMP cation containing structures feature HgBr4 and ZnBr4 isolated tetrahedra in (C5H7N2)2HgBr4·H2O (1) and (C5H7N2)2ZnBr4 (2), respectively. The presence of isolated molecular units in the zero-dimensional structures results in strongly localized charges and bright WL luminescence with corresponding Commission Internationale de l’Eclairage color coordinates of (0.34, 0.38) and (0.25, 0.26), correlated color temperatures of 5206 K (1) and 11 630 K (2), and very high color rendering indexes (CRI) of 87 (1) and 96 (2). The visibly bright WL emission at room temperature is corroborated with high measured photoluminescence quantum yield values of 14.87 and 19.18% for 1 and 2, respectively. Notably, the high CRI values for these new HOIMs exceed the commercial requirements and produce both “warm” and “cold” WL depending on the metal used (Hg or Zn). Based on temperature- and powder-dependent photoluminescence (PL), PL lifetimes measurements and density functional theory calculations, the broadband WL emission is assigned to the 4AMP organic molecules emission and self-trapped states

Hybrid Organic–Inorganic Halides (C₅H₇N₂)₂MBr₄ (M = Hg, Zn) with High Color Rendering Index and High-Efficiency White-Light Emission

Low-dimensional hybrid organic–inorganic materials (HOIMs) are being widely investigated for their unique optoelectronic properties. Some of them exhibit broadband white-light (WL) luminescence upon UV excitation, providing a potential for the fabrication of single-component white-light-emitting diodes. Here, we report new examples of low-dimensional HOIMs, based on 4-aminopyridinium (4AMP) and group 12 metals (Hg and Zn), for single-component WL emission. The 4AMP cation containing structures feature HgBr4 and ZnBr4 isolated tetrahedra in (C5H7N2)2HgBr4·H2O (1) and (C5H7N2)2ZnBr4 (2), respectively. The presence of isolated molecular units in the zero-dimensional structures results in strongly localized charges and bright WL luminescence with corresponding Commission Internationale de l’Eclairage color coordinates of (0.34, 0.38) and (0.25, 0.26), correlated color temperatures of 5206 K (1) and 11 630 K (2), and very high color rendering indexes (CRI) of 87 (1) and 96 (2). The visibly bright WL emission at room temperature is corroborated with high measured photoluminescence quantum yield values of 14.87 and 19.18% for 1 and 2, respectively. Notably, the high CRI values for these new HOIMs exceed the commercial requirements and produce both “warm” and “cold” WL depending on the metal used (Hg or Zn). Based on temperature- and powder-dependent photoluminescence (PL), PL lifetimes measurements and density functional theory calculations, the broadband WL emission is assigned to the 4AMP organic molecules emission and self-trapped states

Bright Luminescence from Nontoxic CsCu₂X₃ (X = Cl, Br, I)

Inexpensive and highly efficient luminescent materials based on multinary halides have received increased attention in recent years. Among those considered most promising are the perovskites such as CsPbX3 because of their highly efficient and tunable emission through precise control of chemical composition and nanostructuring. However, the presence of the toxic heavy metal Pb and relatively poor stability are among the major challenges for the introduction of lead-halide-based materials into the marketplace. Here, we report the optical properties of nontoxic and highly emissive one-dimensional (1D) all-inorganic halides CsCu2X3 (X = Cl, Br, I) and their mixed halide derivatives, which also show improved thermal and air stability. Photoluminescence (PL) measurements show tunable bright room temperature emission from green to yellow with photoluminescence quantum yields ranging from 0.37 (CsCu2Cl1.5Br1.5) to 48.0% (CsCu2Cl3). Temperature- and power-dependent PL measurements suggest that the emission results from self-trapped excitons induced by strong charge localization and structural distortions within the lD ribbon structure

Rb₄Ag₂BiBr₉: A Lead-Free Visible Light Absorbing Halide Semiconductor with Improved Stability

Replacement of the toxic heavy element lead in metal halide perovskites has been attracting a great interest because the high toxicity and poor air stability are two of the major barriers for their widespread utilization. Recently, mixed-cation double perovskite halides, also known as elpasolites, were proposed as an alternative lead-free candidate for the design of nontoxic perovskite solar cells. Herein, we report a new nontoxic and air stable lead-free all-inorganic semiconductor Rb4Ag2­BiBr9 prepared using the mixed-cation approach; however, Rb4Ag2­BiBr9 adopts a new structure type (Pearson’s code oP32) featuring BiBr6 octahedra and AgBr5 square pyramids that share common edges and corners to form a unique 2D layered non-perovskite structure. Rb4Ag2­BiBr9 is also demonstrated to be thermally stable with the measured onset decomposition temperature of To = 520 °C. Optical absorption measurements and density functional theory calculations suggest a nearly direct band gap for Rb4Ag2­BiBr9. Room temperature photoluminescence (PL) measurements show a broadband weak emission. Further, temperature-dependent and power-dependent PL measurements show a strong competition between multiple emission centers and suggest the coexistence of defect-bound excitons and self-trapped excitons in Rb4Ag2­BiBr9