Al 3+ -added Cs 2 AgInCl 6 and Cs 2 AgBiCl 6 catalysts were prepared by co-precipitation method. It is shown that the incorporation of high concentration of Al 3+ in Cs 2 AgInCl 6 (20% Al 3+ or above) and in Cs 2 AgBiCl 6 (with 50% Al 3+ or above) causes obvious phase separation and formation of secondary phase (AgCl). And the optical bandgaps of Al 3+ -added Cs 2 AgInCl 6 and Al 3+ -added Cs 2 AgBiCl 6 are about 3.5 eV and 2.7 eV, respectively. Benefiting from the enhanced carrier transfer in AgCl/Cs 2 AgInCl 6 heterojunction, Cs 2 AgInCl 6 :0.9Al 3+ exhibits excellent degradation performance for Sudan Red III with a rate above 97% within 16 min and catalytic cycles above 4 times. And Cs 2 AgBiCl 6 :0.7Al 3+ can degrade Sudan Red III at a rate higher than 96% within 14 min. And a new degradation pathway of Sudan Red III in ethanol solutions was proposed firstly. The Al 3+ -added Cs 2 AgInCl 6 and Cs 2 AgBiCl 6 catalysts also exhibit good cyclic and storage stabilities, showing potential applications in the photodegradation of organic pollutants.
Lead-free halide double perovskites (DPs) have attracted much attention due to their potential applications in the field of near-infrared (NIR) optoelectronics. However, regulating the NIR luminescence properties of such materials remains a challenge. In this study, it is found that Cs 2 AgInCl 6 :Cr 3+ DPs exhibit a broad NIR emission under ultraviolet excitation, with a peak value of 980 nm. In the range of 9 GPa, the emission intensity increases significantly. As the pressure increases, a transition from broadband NIR emission to narrow-line emission occurs, accompanied by a decrease in the full width at half maximum (FWHM) from 260 to 40 nm, attributed to increased local structural asymmetry and enhanced crystal field around Cr 3+ ions. Ultrafast transient absorption experiments reveal the changes of energy transfer under pressure and the emergence of new radiation channels, demonstrating the dynamic evolution of emission characteristics under high pressure. The research results deepen the understanding of high pressure luminescence in Cr 3 ⁺-doped halide DPs, providing strategies for designing highly efficient NIR emitters in metal halide DPs.
In recent years, the lead-free halide perovskite has been extensively studied due to the the lead toxicity and poor stability of lead halide perovskite. Cs2AgInCl6 has shown great potential to replace lead halide perovskites in optoelectronic applications. However, this perovskite synthesis method needs to involve high temperature, the synthesis conditions are relatively harsh. In this work, a simple solid-phase grinding method was employed to prepare Na+ and Bi3+ doped perovskite Cs2Ag1-xNaxIn1-yBiyCl6 with systematically characterization of both the structure and optical performance. The experimental results showed that a photoluminescence quantum yield (PLQY) of 13.1% was achieved by breaking the parity-forbidden transition through 4% Bi³⁺ doping. Subsequently, the incorporation of 60% Na⁺ suppressed non-radiative transitions and increased the PLQY to 56.9%. The Cs2Ag0.4Na0.6In0.96Bi0.04Cl6 samples were encapsulated on ultraviolet (UV) LED chips to obtain warm-yellow LED with good performances, which shows that promising applications in the LED field.
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