Low-dimensional lead-based perovskite materials have recently attracted extensive attentions for their diverse structures, unique optoelectronic properties and enhanced stability. However, the toxicity of lead, low photoluminescence quantum yield (PLQY) and complex preparation processes limit their practical applications. Herein, we present a simple room-temperature synthesis of orange-emitting lead-free perovskite derivative (NH 4 ) 2 SnCl 6 :Te phosphors with a large quantity at one time. By introducing Te 4+ ions with 5s 2 active lone pairs, (NH 4 ) 2 SnCl 6 :Te exhibits broadband emission peaked at 590 nm, a large full width at half maximum (FWHM) about 127 nm and a maximum PLQY up to 83.51%. Density functional theory calculations combined with comprehensive spectroscopic data reveal that the incorporated Te 4+ ions change the band structure and trigger the formation of Jahn-Teller-like self-trapped excitons (STEs) in [TeCl 6 ] 2− centers. In addition, (NH 4 ) 2 SnCl 6 :Te shows excellent ambient and thermal stabilities. Using (NH 4 ) 2 SnCl 6 :0.5%Te as an orange down-conversion material, highly stable wLEDs with a Commission Internationale de l’Eclairage (CIE) of (0.39, 0.38), correlated color temperature (CCT) of 3855 K, and color rendering index (CRI) of 83 are demonstrated. We expect these results to facilitate the development of low-cost, environmentally friendly and high-performance novel phosphors for future lighting and display technologies.
Ruxin Liu,Kaishun Zou,Guanglu Zhang,Min Feng,Mingxuan Li,Juncheng Liu
Vacancy-ordered double perovskites (VODPs) have attracted much attention because of their excellent photoelectric properties. However, the competition mechanism of self-trapped exciton emission and Te4+ ion emission in Te4+-doped VODPs is still unclear. Herein, we synthesized Rb2HfCl6 microparticles with a blue self-trapped excitons (STEs) emission, which have a near-unity photoluminescence quantum yield (PLQY), the highest reported value (98.56%) for a VODP matrix. In addition, it has a new broadband yellow emission peak at 560 nm with a PLQY of 76.72% via the equivalent doping of Te4+ ions. The combination of the blue luminescence of pristine Rb2HfCl6 with the yellow luminescence from the Te4+ ion emission could be used in fluorescence anti-counterfeiting. We also prepared a white light-emitting diode (WLED) with the Commission Internationale de l'Eclairage (CIE) coordinates at (0.3502, 0.3527), a correlated color temperature (CCT) of 4814 K and a color-rendering index (CRI) of 75.3. Moreover, optimized Rb2HfCl6:Te4+ exhibited excellent air and thermal stability. The luminescence dynamics and theoretical calculations jointly reveal that this efficient emission originates from the electron transitions in the different paths. This work provides a new perspective and new theoretical support for the future research on ion-doped luminescent systems.
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