Controlling Photoluminescence and Photocatalysis Activities in Lead‐Free Cs 2 Pt x Sn 1− x Cl 6 Perovskites via Ion Substitution

Multimodal Luminescent Low-Dimension Cs2ZrCl6:xSb3+ Crystals for White Light-Emitting Diodes and Information Encryption

Low-dimension perovskite materials have attracted wide attention due to their excellent optical properties and stability. Herein, Sb³⁺-doped Cs₂ZrCl₆ crystals are synthesized by a coprecipitation method in which Sb³⁺ ions partially replace Zr⁴⁺ ions. The Cs₂ZrCl₆:xSb³⁺ powder shows blue and orange-red emissions under a 254 and 365 nm light, respectively, due to the [ZrCl₆]^2- octahedron and [SbCl₆]^3- octahedron. The photoluminescence quantum yield (PLQY) of Cs₂ZrCl₆:xSb³⁺ (x = 0.1) crystals is up to 52.5%. According to experimental and computational results, the emission mechanism of the Cs₂ZrCl₆:xSb³⁺ crystals is proposed. On the one hand, a wide blue emission with a large Stokes shift is caused by the self-trapping excitons of [ZrCl₆]^2- octahedra under a 260 nm excitation. On the other hand, the luminescence mechanism of [SbCl₆]^3- octahedron is divided into two parts: ¹P₁ → ¹S₀ (490 nm) and ³P₁ → ¹S₀ (625 nm). The broad-band emission, high PLQY, and excellent stability endow the Cs₂ZrCl₆:xSb³⁺ powders with the potential for the fabrication of white light-emitting diodes (WLEDs). A WLED device is fabricated using a commercial 310 nm NUV chip, which shows a high color rendering index of 89.7 and a correlated color temperature of 5333 K. In addition, the synthesized Cs₂ZrCl₆:xSb³⁺ crystals can be also successfully used for information encryption. Our work will provide a deep understanding of the photophysical properties of Sb³⁺-doped perovskites and facilitate the development of Cs₂ZrCl₆:xSb³⁺ crystals in encrypting multilevel optical codes and WLEDs.

Efficient Near-Infrared Luminescence in Lanthanide-Doped Vacancy-Ordered Double Perovskite Cs2 ZrCl6 Phosphors via Te4+ Sensitization

All-inorganic lead-free perovskite-derivative metal halides have shown great promise in optoelectronics, however, it remains challenging to realize efficient near-infrared (NIR) luminescence in these materials. Herein, we report a novel strategy based on Te⁴⁺ /Ln³⁺ (Ln=Er, Nd, and Yb) co-doping to achieve efficient NIR luminescence in vacancy-ordered double perovskite Cs₂ ZrCl₆ phosphors, which are excitable by a low-cost near-ultraviolet light-emitting diode (LED) chip. Through sensitization by the spin-orbital allowed ¹ S₀ →³ P₁ transition of Te⁴⁺ , intense and multi-wavelength NIR luminescence originating from the 4f→4f transitions of Er³⁺ , Nd³⁺ , and Yb³⁺ was acquired, with a quantum yield of 6.1 % for the Er³⁺ emission. These findings provide a general approach to achieve efficient NIR emission in lead-free metal halides through ns² -metal and lanthanide ion co-doping, thereby opening up a new avenue for exploring NIR-emitting perovskite derivatives towards versatile applications such as NIR-LEDs and bioimaging.

Dual-Band-Tunable White-Light Emission from Bi3+ /Te4+ Emitters in Perovskite-Derivative Cs2 SnCl6 Microcrystals

Luminescent metal halides have attracted considerable attention in next-generation solid-state lighting because of their superior optical properties and easy solution processibility. Herein, we report a new class of highly efficient and dual-band-tunable white-light emitters based on Bi³⁺ /Te⁴⁺ co-doped perovskite derivative Cs₂ SnCl₆ microcrystals. Owing to the strong electron-phonon coupling and efficient energy transfer from Bi³⁺ to Te⁴⁺ , the microcrystals exhibited broad dual-band white-light emission originating from the inter-configurational ³ P_0,1 →¹ S₀ transitions of Bi³⁺ and Te⁴⁺ , with good stability and a high photoluminescence (PL) quantum yield of up to 68.3 %. Specifically, a remarkable transition in Bi³⁺ -PL lifetime from milliseconds at 10 K to microseconds at 300 K was observed, as solid evidence for the isolated Bi³⁺ emission. These findings provide not only new insights into the excited-state dynamics of Bi³⁺ and Te⁴⁺ in Cs₂ SnCl₆ , but also a general approach to achieve single-composition white-light emitters based on lead-free metal halides through ns² -metal ion co-doping.