Thermally Stable Self‐Trapped Assisted Single‐Component White Light from Lead‐Free Zero‐Dimensional Metal Halide Nanocrystals

Abstract

White‐light‐emitting single‐component materials are in high demand for lighting applications. However, achieving white light in single‐doped metal halide materials remains a challenge. Herein, for the first time, zero‐dimensional Cs3ScCl6:Sb3+(CSC:Sb3+) nanocrystals (NCs) are reported that exhibit bright white‐light emission, which is a result of combination of the excessive blue and yellow emissions of carbon dots and spin‐forbidden electronic transitions of Sb3+ ions. CSC:Sb3+ NCs exhibit a high photoluminescence quantum yield of 48%. Furthermore, they retain 75% of their original photoluminescence efficiency at 100 °C. This high thermal stability is mainly attributed to its lower dimensionality and high exciton binding energy as they facilitate the creation of stable white light at elevated temperatures. A single‐component white‐light‐emitting diode fabricated using CSC:Sb3+ NCs exhibits a high‐color rendering index and luminous efficacy values of 90 and 23 lm W−1 at a high flux current of 200 mA. Therefore, the findings may pave the way for developing the next generation of white‐light‐emitting devices using a single component of white‐light‐emitting material.

A Robust Anti-Thermal-Quenching Phosphor Based on Zero-Dimensional Metal Halide Rb3InCl6:xSb3+

“…The formation of vacancies was further proven by 85 Rb magic angle spinning (MAS) nuclear magnetic resonance (NMR) characterization (Figure S18), which evidenced at least four different 85 Rb peaks in the range from 100 to −100 ppm. Considering that Rb + ions occupy two different locations (Rb 1 , Rb 2 ) in the tetragonal Rb 3 InCl 6 phase, the NMR spectra indicated that the two types of Rb atoms could be surrounded by either 6 [InCl 6 ] 3– or 5 [InCl 6 ] 3– octahedra and 1 In vacancy, , which further splits the number of Rb sites to four, (Rb 1 , Rb 1‑v ) and (Rb 2 , Rb 2‑v ), resulting in 2*2 multiplets. As the synthesis conditions employ nonstoichiometric ratios (in particular, insufficient In precursors), the defects here could be B 3+ site vacancies, with an energy depth of 0.8–1.0 eV and a density of 2.3 × 10 10 cm –3 , as determined by thermally stimulated current (TSC) and space-charge-limited current (SCLC) analyses (reported in Figure S19).…”

“…[10][11][12]20 Several Sb-doped metal halides were reported to have good thermal stability of their luminescence, although far lower than any other reported metal oxide/nitride-based anti-TQ phosphor. 21,22 Huang et al reported Mn 2+ -doped CsPb(Cl/Br) 3 halide perovskite nanocrystals offering thermally stable (or even enhanced) red emission up to 323 K, which was attributed to thermally activated energy transfer from excitonic to Mn 2+ acceptor states. perovskite nanocrystals with a temperature-independent emission from 298 to 373 K. 10 The fluorine-rich shell was purported to have a wider energy gap than the inner nanocrystal core, suppressing carrier trapping and improving thermal stability.…”

“…Metal halides, on the other hand, can profit from the much lower synthesis temperatures (some of them can even be prepared at room temperature) and, for some members of the class, the high photoluminescence quantum yield (PLQY). Indeed, various metal halides have been explored as potential candidates for anti-TQ phosphors. − , Several Sb-doped metal halides were reported to have good thermal stability of their luminescence, although far lower than any other reported metal oxide/nitride-based anti-TQ phosphor. , Huang et al reported Mn 2+ -doped CsPb­(Cl/Br) 3 halide perovskite nanocrystals offering thermally stable (or even enhanced) red emission up to 323 K, which was attributed to thermally activated energy transfer from excitonic to Mn 2+ acceptor states. , Liu et al reported fluorine-treated CsPbBr 3 perovskite nanocrystals with a temperature-independent emission from 298 to 373 K . The fluorine-rich shell was purported to have a wider energy gap than the inner nanocrystal core, suppressing carrier trapping and improving thermal stability. , Han et al found that Mn 2+ -doped Rb 3 Cd 2 Cl 7 single crystals did not suffer from luminescence intensity quenching up to 423 K. ,, More recently, Zhou et al developed a Zr 4+ /Mn 2+ codoped CsCdCl 3 system featuring a robust anti-TQ radioluminescence up to 448 K, a record value for metal halide materials .…”

High-Throughput Screening on Halide Perovskite Derivatives and Rational Design of Cs3LuCl6

“…The conventional ABX 3 perovskite structure has 3D connectivity of BX 6 octahedra; however, such a polyhedral connectivity in perovskite derivatives can be reduced to 2D, 1D, or even 0D by choosing a heterovalent B ion (replacing Pb 2+ ) or changing the stoichiometry. This reduction of connectivity can enhance their environmental stability, improve moisture resistance, and allow for tunable bandgaps, which make them promising candidates for various optoelectronic applications. , The example cases are Cs-Mn-Cl in A 2 B 1 X 4 , Cs-Tb-Cl and Cs-Sc-Cl in B 3 B 1 B 6 , and so on. Their compositional diversity and structural dimensionality, , however, require numerous efforts to explore novel materials in almost infinite chemical spaces despite their promising potentials. − Thereby the development in the field of perovskite derivatives is still in its infancy, necessitating further systematic investigations, including the integration of machine learning (ML) and density functional theory (DFT) computations. , In addition, understanding low-dimensional inorganic metal halides’ physical and chemical nature still remains a mystery .…”

“…Next, for the B-site cation, we considered a lead-free series to find alternatives for toxic lead. Generally, Sn, Sb, Ge, and Bi are known as conventional lead-free elements. , In addition to these, new lead-free series have recently been discovered in transition metals, ,− post-transition metals, ,− and even lanthanides. ,, These series exhibit moderate environmental stability with usable optoelectronic performance but are still extremely uncommon. Hence, 36 lead-free metals encompassing transition metals, post-transition metals, and lanthanides were selected as the B-site cations, excluding certain precious and toxic elements.…”