One-Dimensional Lead-Free Halide with Near-Unity Greenish-Yellow Light Emission

Abstract

Low-dimensional metal halides (LDMHs), especially lead-based perovskites, have recently attracted a great deal of attention for their unique structures and optoelectronic properties. However, the toxicity of lead limits their practical applications. Herein, a lead-free one-dimensional copper-based halide [KC 2 ] 2 [Cu 4 I 6 ] (C = 12-crown-4 ether) was constructed, which exhibits greenish-yellow emission (545 nm) with a near-unity photoluminescence quantum yield (∼97.8%). To the best of our knowledge, this is the highest value that has been achieved in leadfree greenish-yellow light-emitting LDMHs. Density functional theory calculations combined with comprehensive spectroscopic data revealed the characteristics of self-trapped exciton emission. Finally, we explored the application of the [KC 2 ] 2 [Cu 4 I 6 ] phosphor by fabricating the white light-emitting diode (WLED) device. The WLEDs fabricated using commercially available blue (450 nm) and ultraviolet (365 nm) as the excitation source both present excellent luminescence properties with a high color rendering index and a suitable corresponding color temperature. Our findings not only expand the library of highly efficient luminescent materials but also highlight the potential of low-dimensional copper-based halides in optoelectronics.

Highly Efficient Self-Trapped Bluish White-Light Emission from [Pb 4 Cl 5 ] 3+ Nodes in a Moisture-Tolerant Metal–Organic Framework

“…The valence band maximum (VBM) and conduction band minimum (CBM) are dominated by the full Cl 3p orbitals and empty Pb 5p orbitals, respectively, analogous to lead halide perovskites. 37,38 Meanwhile, O 2p and C 2p orbitals from adatc 4− ligands partially contribute to the VBM and CBM, respectively, likely due to the Pb 2+ -carboxylate coordination in TJU-20 (Figure 3b). This is further confirmed by the density contour maps for lowest unoccupied molecular orbitals (LUMO) and highest occupied molecular orbitals (HOMO) (Supporting Information Figure S8).…”

Photoluminescence of Singlet/Triplet Self‐Trapped Excitons in Sb3+‐Based Metal Halides

“…Recently, a hybrid metal halide excited by blue light was reported with a near unity PLQY and a WLED device was fabricated by using a commercially blue LED (450 nm). [ 50 ] Though the LE value is not provided here, this paves a promising way to realize the excitation wavelength adjustment to improve LE. Therefore, the optimization of excitation wavelength of Sb 3+ ‐based metal halides is significant for highly efficient WLED devices.…”

Mn2+‐Doped Metal Halide Perovskites: Structure, Photoluminescence, and Application

“…[ 47–57 ] The toxic‐lead existence is a bottleneck of metal halide perovskites for extending their applications, and thus plentiful elements (e.g., Cu + , Cu 2+ , Sn 2+ , Sn 4+ , Sb 3+ , Bi 3+ , In 3+ ) act as Pb 2+ ‐free candidates to form various perovskite structures. [ 16,58–71 ] Although composition engineering enables the appearance of metal halide perovskite with different structures and dimensions, lead‐free perovskite‐type compounds still exhibit some disadvantages, which include relatively low photoluminescence quantum yields (PLQY), poor stability against high temperature and moisture, enabling poor device performance. As an example, lead‐free CsSnBr 3 perovskites nanocrystals (NCs) show the low PLQY and bad stability, the oxidation of Sn 2+ to Sn 4+ greatly impedes their development.…”