Intervalence charge transfer of Cr^(3+)-Cr^(3+) aggregation for NIR-Ⅱ luminescence

The increasing demand for high-contrast biological imaging,non-destructive testing,and infrared night vision can be addressed by the development of high-performance NIR light-emitting materials.Unlike lanthanide(Ln^(3+))with sharp-line multiplets and isolated Cr^(3+)with NIR-I emission,this study reports the first-ever NIR-Ⅱ broadband luminescence based on the intervalence charge transfer(IVCT)of Cr^(3+)-Cr^(3+)aggregation in gallate magentoplumbite.In particular,LaMgGa11O19:0.7Cr^(3+)exhibits dual-emission(NIR-I,890 nm and NIR-Ⅱ,1200 nm)with a full width at half maximum(FWHM)of 626 nm under 450 nm blue LED excitation.Moreover,this dual-emission exhibits anti-thermal quenching behavior(432%@290 K),attributed to the energy transfer among multiple Cr^(3+)centers.Cryogen absorption spectra,lifetimes decay(2.3 ms),and electron paramagnetic experiments reveal the NIR-Ⅱ luminescence of the Cr^(3+)-Cr^(3+)→Cr^(2+)-Cr^(4+)IVCT transition.The application of LaMgGa_(11)O_(19)∶0.7Cr^(3+)in NIR-Ⅱ biological imaging as an optical contrast agent,non-destructive testing,and night vision is demonstrated.This work provides new insights into broadband NIR-Ⅱ luminescence under UV-NIR excitation based on the IVCT of Cr^(3+)-Cr^(3+)aggregation.

High-security-level multi-dimensional optical storage medium:nanostructured glass embedded with LiGa_(5)O_(8):Mn^(2+) with photostimulated luminescence

The launch of the big data era puts forward challenges for information preservation technology,both in storage capacity and security.Herein,a brand new optical storage medium,transparent glass ceramic(TGC)embedded with photostimulated LiGa5O8:Mn2+nanocrystals,capable of achieving bit-by-bit optical data write-in and read-out in a photon trapping/detrapping mode,is developed.The highly ordered nanostructure enables light–matter interaction with high encoding/decoding resolution and low bit error rate.Importantly,going beyond traditional 2D optical storage,the high transparency of the studied bulk medium makes 3D volumetric optical data storage(ODS)possible,which brings about the merits of expanded storage capacity and improved information security.Demonstration application confirmed the erasable-rewritable 3D storage of binary data and display items in TGC with intensity/wavelength multiplexing.The present work highlights a great leap in photostimulated material for ODS application and hopefully stimulates the development of new multi-dimensional ODS media.

Carbon dots embedded in lead-free luminescent metal halide crystals toward single-component white emitters

The development of single-component white emitters for white light-emitting diodes(WLEDs)remains challenging.Herein,a rare earth-free white light-emitting composite is developed by assembling blue-emitting carbon dots(CDs)and yellow-emitting Cs_(2)InCl_(5)·H_(2)O:Sb^(3+)metal halide crystals via a facile liquid-liquid diffusion-assisted crystallization approach.The encapsulation mechanism is then analyzed.Depending on the ratios of blue/yellow emitters,these luminescent composites exhibit white light emission with tunable cold and warm hues.The composites also possess prominent ultraviolet resistance,thermal tolerance,and good stability at about 200°C.By employing such“CDs in metal halide”composites as a converter,a WLED is successfully fabricated with a high color rendering index of 93.6,benefiting from the assembled blue and yellow broadband emission.With this strategy,the developed composites show great promise in next-generation WLED lighting.