Multimode Luminescence Tailoring and Improvement of Cs₂NaHoCl₆ Cryolite Crystals via Sb³⁺/Yb³⁺ Alloying for Versatile Photoelectric Applications

Abstract

Lead‐free halide double perovskites are currently gaining significant attention owing to their exceptional environmental friendliness, structural adjustability as well as self‐trapped exciton emission. However, stable and efficient double perovskite with multimode luminescence and tunable spectra are still urgently needed for multifunctional photoelectric application. Herein, holmium based cryolite materials (Cs2NaHoCl6) with anti‐thermal quenching and multimode photoluminescence were successfully synthesized. By the further alloying of Sb3+ (s‐p transitions) and Yb3+ (f‐f transitions) ions, its luminescence properties can be well modulated, originating from tailoring band gap structure and enriching electron transition channels. Upon Sb3+ substitution in Cs2NaHoCl6, additional absorption peaking at 334 nm results in the tremendous increase of photoluminescence quantum yield (PLQY). Meanwhile, not only the typical NIR emission around 980 nm of Ho3+ is enhanced, but also the red and NIR emissions show a diverse range of anti‐thermal quenching photoluminescence behaviors. Furthermore, through designing Yb3+ doping, the up‐conversion photoluminescence can be triggered by changing excitation laser power density (yellow‐to‐orange) and Yb3+ doping concentration (red‐to‐green). Through a combined experimental‐theoretical approach, the related luminescence mechanism is revealed. In general, by alloying Sb3+/Yb3+ in Cs2NaHoCl6, abundant energy level ladders are constructed and more luminescence modes are derived, demonstrating great potential in multifunctional photoelectric applications.

The luminescence modulation of rare earth-doped/containing lead-free double perovskites toward multifunctional applications: a review

“…The same group simultaneously realized UC and DS luminescence in Cs 2 NaHoCl 6 through Yb 3+ doping. 75 As shown in Fig. 6h, the XRD pattern of Cs 2 NaHoCl 6 DPs agrees well with that of the standard file.…”

“…5e. 75 The electron energy band structure has been calculated using density functional theory, which reveals the contribution of Sb 3+ ions both in the conduction band minimum and valence band maximum, indicating the feasibility of the 5s–5p transition of Sb 3+ ions. The emergence of new absorption bands increases the 4f–4f transition possibility of Ho 3+ , enabling a high PLQY.…”

“…As the power of the 980 nm laser was increased from 29.8 to 470.3 mW, the emission color changed from yellow to orange. 75…”

“…10c, the Yb 3+ , Sb 3+ co-doped Cs 2 NaHoCl 6 DPs exhibit a color change at different excitation wavelengths and powers as well as dopant concentrations. 75…”

Synthesis of Metastable Silver-Lanthanide Double Perovskite Nanocrystals with White-Light Emission

“…Recently, lanthanide-based double perovskites ( A 2 M I LnX 6 , A = Cs + , M I = Na + , X = Cl – , Br – , and I – ) have been prepared in both bulk phase and colloidal NCs. − These lanthanide perovskites display interesting properties, including the highest PLQY in the ultraviolet C (UV–C, 180–280 nm) range, sharp near-infrared (NIR) photoluminescence at telecommunication wavelength (1260–1675 nm), multimode and antithermal quenching luminescence, and tunable bandgap and magnetic properties . However, only alkali metal ions have been demonstrated in lanthanide double perovskites.…”