Doped Halide Perovskite Research Articles

Multi-mode excited upconversion and downshifting of Ho3+/Yb3+ doped lead-free double perovskite Cs2NaBiCl6 for anti-counterfeiting and thermometry

Rear earth(RE)-doped halide perovskite has generated as an amazing optical material for multicolor luminescence. Free-lead halide double perovskites have attracted interesting because of their non-toxicity and higher instability. Here, RE3+ doped chloride-based double perovskite phosphors are reported. A series of heavy concentration Ho3+/Yb3+ doped Cs2NaBiCl6(CNBC) phosphors are prepared with a solvothermal route. The band structure of CNBC is calculated through density functional theory (DFT). The luminescence properties of CNBC:Ho3+ and CNBC:Ho3+/Yb3+ are investigated through upconversion(UC) and downshifting(DS) processes. From CNBC:Ho3+, the brightness orange, deep red and pale green lights are achieved under excitation at 365, 452 and 980 nm. The multicolor emissions of CNBC:Ho3+ are used to multimode fluorescent anti-counterfeiting. Comparing with CNBC:Ho3+ samples, the UC emission intensity of CNBC:Ho3+/Yb3+ are dramatically enhanced. The brightness green light can be seen by naked eyes under super lower power pumping(∼10 mW). The temperature sensing properties of CNBC:Ho3+/Yb3+ phosphor are investigated systematically based on the luminescence intensity ratio(LIR) of thermally coupled levels(TCLs)(5F1/5G6,5F2,3/3K8) and non-TCLs(5F4/5S2,5F5). The maximum relative sensitivity(SR) reaches 5.089% K−1 at 293 K according to the LIR of non-TCLs. The work will broaden the application field of RE3+-doped free-lead perovskite such as anti-counterfeiting and thermometry.

Modulation of the Excitation States in All-Inorganic Halide Perovskites via Sb3+ and Bi3+ Codoping

Sb3+-doped halide perovskites are promising candidates for solid-state lighting due to their diverse fluorescent colors and high efficiency. However, the mismatched high excitation energy with commercial UV chips is one of the critical issues to be addressed. Herein, a Bi3+ codoping strategy was established as a general and efficient approach to modulate the excitation spectrum from the Sb3+-doping center in all-inorganic perovskites of Cs2InCl5·H2O, Cs2NaInCl6, and Rb3InCl6. The incorporated Bi3+ greatly enhanced the splitting of the A band (1S0-3P1 transition) and boosts the enormous redshift of the low-energy branch in all these systems. The interactions persist strongly even at extremely low doping concentrations, suggesting a dipole-based long-range interaction. The results provide an in-depth insight into the contribution mechanism of Bi3+ to Sb3+ in all-inorganic perovskites, which throws light upon tuning the excitation spectrum of broadband emission from the extrinsic self-trapped exciton (STE).

Efficient Energy Transfer in Te4+-Doped Cs2ZrCl6 Vacancy-Ordered Perovskites and Ultrahigh Moisture Stability via A-Site Rb-Alloying Strategy.

As an effective method to improve the optical properties and stability of perovskite matrix, doped halide perovskites have attracted extensive attention in the field of optoelectronic applications. Herein, a series of all inorganic lead-free Te4+-doped Cs2ZrCl6 vacancy-ordered perovskites were successfully synthesized with different Te-doping concentrations by a solvothermal method, and deliberate Te4+-doping results in green-yellow triplet self-trapped exciton (STE) emission with a high photoluminescence quantum yield (PLQY) of 49.0%. The efficient energy transfer was observed from singlet to triplet emission. Further, the effects of A-site Rb alloying on the optical properties and stability were investigated. We found that A-site Rb alloying and C-site cohalogenation did not change the luminescence properties of Te4+, but the addition of a small amount of Rb+ can improve the PL intensity and moisture stability. Our results provide physical insights into the nS2 Te4+-ion-doping-induced emissive mechanism and shed light on improving the environmental stability for further applications.

Photoluminescence Saturation in Quantum-Cutting Yb3+-Doped CsPb(Cl1–xBrx)3 Perovskite Nanocrystals: Implications for Solar Downconversion

Yb3+-doped halide perovskites have recently emerged as extraordinarily promising materials for solar spectral downconversion applications because of their extremely high photoluminescence quantum y...