Mn^(2+)离子掺杂制备的高效红光发射无铅铯钪卤化物钙钛矿晶体

通过简便的湿化学方法,将Mn^(2+)离子掺杂到Cs_(2)ScCl_(5)·H_(2)O钙钛矿中,可以快速合成具有高光致发光量子产率的钙钛矿晶体.在红光区掺杂Mn^(2+)的钙钛矿晶体的量子产率比主体材料高出12倍以上,比CsMnCl_(3)·2H_(2)O高出近24倍.此外,利用密度泛函理论计算研究了材料的轨道杂化性质,进一步研究了材料的光学性质.Mn^(2+)掺杂后,被Sc八面体分离的Mn八面体可以更有效地限制激子,有利于提高量子产率.与原来的带隙相反,出现了归属于Mn和宿主元素的新杂化轨道.掺杂样品的吸收和激发范围从深紫外吸收扩展到紫外和可见吸收.基于上述性质,利用掺杂Mn^(2+)的钙钛矿制备了蓝芯片激发的高效白色发光二极管,其显色指数高达91,为未来在光电子领域的应用开辟了道路.

Stress-induced CsPbBr3 nanocrystallization on glass surface:Unexpected mechanoluminescence and applications

In this work,we discovered an unexpected mechanoluminescence (ML) phenomena occurring when transforming amorphous into crystalline,due to the stress-induced precipitation of CsPbBr3 perovskite nanocrystals on glass surface.It is revealed that,unlike the conventional thermal-induced phase transformation mechanism,the breakage of bonding of glass network provides the energy for nucleation and growth,and the shear stress avoids the long-range migration of structural units for crystallization.Such unique ML phenomenon enables the visualization of dynamical force that is inaccessible by common strategy,and so,opens up some novel applications,such as the pressure-sensitive "glassy pencil" to learn people's writing habits,and the pb^2+-detection with good sensitivity and selectivity.These findings not only demonstrate an effective route for the preparation of perovskite materials in a green,time-saving,low cost,and scalable way,enrich the knowledge of glass crystallization mechanism,but also exploit a useful avenue to quantitatively visualize the dynamical force.

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.

Compact ultrabroadband light-emitting diodes based on lanthanide-doped lead-free double perovskites

Impurity doping is an effective approach to tuning the optoelectronic performance of host materials by imparting extrinsic electronic channels.Herein,a family of lanthanide(Ln^(3+))ions was successfully incorporated into a Bi:Cs_(2)AgInCl_(6) lead-free double-perovskite(DP)semiconductor,expanding the spectral range from visible(Vis)to near-infrared(NIR)and improving the photoluminescence quantum yield(PLQY).After multidoping with Nd,Yb,Er and Tm,Bi/Ln:Cs_(2)AgInCl_(6) yielded an ultrabroadband continuous emission spectrum with a full width at half-maximum of~365 nm originating from intrinsic self-trapped exciton recombination and abundant 4f-4f transitions of the Ln^(3+)dopants.Steady-state and transient-state spectra were used to ascertain the energy transfer and emissive processes.To avoid adverse energy interactions between the various Ln^(3+)ions in a single DP host,a heterogeneous architecture was designed to spatially confine different Ln^(3+)dopants via a“DP-in-glass composite”(DiG)structure.This bottom-up strategy endowed the prepared Ln^(3+)-doped DIG with a high PLQY of 40%(nearly three times as high as that of the multidoped DP)and superior long-term stability.Finally,a compact Vis-NIR ultrabroadband(400~2000 nm)light source was easily fabricated by coupling the DiG with a commercial UV LED chip,and this light source has promising applications in nondestructive spectroscopic analyses and multifunctional lighting.

"Chameleon-like" optical behavior of lanthanide-doped fluoride nanoplates for multilevel anti-counterfeiting applications

Lanthanide-based luminescent anti-counterfeiting materials are widely used in various kinds of products.However,the emission color of traditional lanthanide-based luminescent materials usually remains nearly unaltered upon different excitation lights,which may only work for single-level anti-counterfeiting.Herein,the NaYbF4∶2%Er@NaYF4 core/shell nanoplates (NPs) with "chameleon-like" optical behavior are developed.These NPs display single-band red or green downshifting (DS) emission upon excitation at 377 or 490 nm,respectively.Upon 980 nm excitation,the color of upconversion (UC) emission can be finely tuned from green to yellow,and to red with increasing the excitation power density from 0.1 to 4.0 W/cm^2.The proposed materials readily integrate the advantages of excitation wavelength-dependent DS single-band emissions and sensitive excitation power-dependent UC multicolor emissions in one and the same material,which has never been reported before.Particularly,the proposed NPs exhibit excellent performance as security labels on trademark tag and security ink on painting,thus revealing the great potential of these lanthanide-doped fluoride NPs in multilevel anti-counterfeiting applications.

Unraveling the triplet excited-state dynamics of Bi^(3+)in vacancyordered double perovskite Cs_(2)SnCl_(6) nanocrystals

Luminescent metal halides doped with ns^(2-)metal ions such as 6s^(2-)metal Bi^(3+)have aroused reviving interest owing to their outstanding optical properties;however,the origin of the photoluminescence(PL)remains controversial and unclear.Herein,we report a strategy for the controlled synthesis of Bi^(3+)-doped vacancy-ordered double perovskite Cs_(2)SnCl_(6)nanocrystals(NCs)and unravel the triplet excited-state dynamics of Bi^(3+)through temperature-dependent PL and ultrafast femtosecond transient absorption spectroscopies.Owing to the aliovalent Bi^(3+)doping in the spatially confined zero-dimensional(0D)structure of Cs2SnCl6,Bi^(3+)ions experience an enhancive Jahn-Teller distortion in the excited state,which results in intense broadband blue PL originating from the inter-configurational 3P0,1→1S0 transitions of Bi^(3+)at 450 nm,with a large Stokes shift and a quantum yield of 35.2%.Specifically,an unusual thermal-enhanced Jahn-Teller splitting of the excitation band and a remarkable transition of the PL lifetime from ms at 10 K toμs at 300 K were observed,as solid evidence for the isolated Bi^(3+)emission.These findings clarify the controversy about the PL origin in ns^(2-)metal ion-doped lead-free luminescent metal halides,thereby paving the way for exploring their optoelectronic applications.

Modulator-directed assembly of hybrid composites based on metalorganic frameworks and upconversion nanoparticles

Hybrid composites made of metal-organic frameworks(MOFs)and lanthanide-doped upconversion nanoparticles(UCNPs)have attracted considerable interest for their synergistically enhanced functions in various applications such as chemical sensing,photocatalysis,anticounterfeiting and nanomedicine.However,precise assembly of MOF/UCNP hybrid composites with tunable morphologies remains a challenge due to the lack of effective synthetic methods and fundamental understanding of the growth mechanisms.Herein,we propose a modulator-directed assembly strategy to synthesize a series of ZIF-8@UCNP composites(ZIF-8=zeolitic imidazolate framework-8).The UCNPs densely paved on the surface of ZIF-8 microcrystals and endowed the composites with intense upconversion blue emission,which were verified by steady-state/transient photoluminescence(PL)spectroscopy and single-particle imaging.Ethylenediamine(EDA)was firstly used as a modulator to fine-tune the predominant MOF facets and realized distinct morphologies of the composites.By adjusting the concentration of EDA from 0 to 25 mmol/L,the morphology of the ZIF-8@UCNP composites was tuned from rhombic dodecahedron(RD)to truncated rhombic dodecahedron(TRD),cube with truncated edges(CTE),cube,and finally a unique form of interpenetration twins(IT).The nucleation and growth process of the ZIF-8@UCNP composites was monitored by time-dependent scanning electron microscopy(SEM)images and the formation mechanism was thoroughly revealed.Furthermore,we demonstrated that the strategy for assembly of morphology-controllable ZIF-8@UCNP composites was generally applicable to various UCNPs with different sizes and shapes.The proposed strategy is expected to open up new avenues for the controllable synthesis of MOF/UCNP composites toward diverse applications.

A strategy for accurate detection of glucose in human serum and whole blood based on an upconversion nanoparticles-polydopamine nanosystem

The accurate detection of blood glucose is of critical importance in the diagnosis and management of diabetes and its complications. Herein, we report a novel strategy based on an upconversion nanoparticles-polydopamine （UCNPs-PDA） nanosystem for the accurate detection of glucose in human serum and whole blood through a simple blending of test samples with ligand-free UCNPs, dopamine, and glucose oxidase （GOx）. Owing to the high affinity of lanthanide ions exposed on the surface of ligand-free UCNPs, dopamine monomers could spontaneously attach to the UCNPs and further polymerize to form a PDA shell resulting in a remarkable upconversion luminescence （UCL） quenching （97.4%） of UCNPs under 980-nm excitation. Such UCL quenching can be effectively inhibited by H2O2 produced from the GOx/glucose enzymatic reaction, thus enabling the detection of H2O2 or glucose based on the UCL quenching/inhibition bioassay. Owing to the highly sensitive UCL response and background-free interference of the UCNPs-PDA nanosystem, we achieved a sensitive, selective, and high-throughput bioassay for glucose in human serum and whole blood, thereby revealing the great potential of the UCNPs-PDA nanosystem for the accurate detection of blood glucose or other HRO2-generated biomolecules in clinical bioassays.

Multiplexed intracellular detection based on dual-excitation/dualemission upconversion nanoprobes

Multiplexed intracellular detection is desirable in biomedical sciences for its higher eficiency and accuracy compared to the single-analyte detection.However,it is very challenging to construct nanoprobes that possess multiple fluorescent signals to recognize the different intracellular species synchronously.Herein,we proposed a novel dual-excitation/dual-emission upconversion strategy for multiplexed detection through the design of upconversion nanoparticles(UCNP)loaded with two dyes for sensitization and quenching of the upconversion luminescence(UCL),respectively.Based on the two independent energy transfer processes of near-infrared(NIR)dye IR845 to UCNP and UCNP to visible dye PAPS-Zn,CIO-and Zn2+were simultaneously detected with a limit of detection(LOD)of41.4 and 10.5 nM,respectively.By tilizing a purpose built 830/980 nm dual-laser confocal microscope,both intrinsic and exogenous CIO and Zn2+in live MCF-7 cells have been accurately quantified.Such dual-excitation/dual-emission ratiometric UCL detection mode enables not only monitoring multiple intracellular analytes but also eliminating the detection deviation caused by inhomogeneous probe distribution in cells.Through modulation of NIR dye and visible dye with other reactive groups,the nanoprobes can be extended to analyze various intraellular species,which provides a promising tool to study the biological activities in live cells and diagnose diseases.

Highly efficient luminescent Ⅰ-Ⅲ-Ⅵ semiconductor nanoprobes based on template-synthesized CuInS2 nanocrystals

CuInS2 semiconductor nanocrystals (NCs) exhibit large absorption coefficient, size-dependent photoluminescence and low toxicity, making them excellent candidates in a variety of bioapplications. However, precise control of both their composition and morphology to improve the luminescent efficiency remains a great challenge via conventional direct synthesis. Herein, we present a novel low-temperature template synthesis of highly efficient luminescent CuInS2 nanoprobes from In2S3 NCs via a facile cation exchange strategy. The proposed strategy enables synthesis of a series of CuInS2 NCs with broad size tunability from 2.2 to 29.6 nm. Through rationally manipulating the stoichiometry of Cu/In, highly efficient luminescence of CuInS2 with the maximum quantum yield of 28.6% has been achieved, which is about one order of magnitude improvement relative to that of directly synthesized NCs. By virtue of the intense emission of CuInS2 nanoprobes, we exemplify their application in sensitive homogeneous biodetection for an important biomolecule of adenosine triphosphate (ATP) with the limit of detection down to 49.3 nM. Moreover, the CuInS2 nanoprobes are explored for ATP-targeted cancer cell imaging, thus revealing their great potentials in the field of cancer diagnosis and prognosis.

A facile ＂ship-in-a-bottle＂ approach to construct nanorattles based on upconverting lanthanide-doped fluorides

Rattle structure is a topic of great interest in design and application of nano- materials due to the unique core@void@shell architecture and the integration of functions. Herein, we developed a novel ＂ship-in-a-bottle＂ method to fabricate upconverting （UC） luminescent nanorattles by incorporating lanthanide-doped fluorides into hollow mesoporous silica. The size of nanorattles and the filling amount of fluorides can be well controlled. In addition, the modification of silica shell （with phenylene and amine groups） and the variation of efficient UC fluorides （NaYF4：Yb, Er, NaLuF4：Yb, Er, NaGdF4：Yb, Er and LiYF4：Yb, Er） were readily achieved. The resulting nanorattles exhibited a high capacity and pH-dependent release of the anti-cancer drug doxorubicin （DOX）. Furthermore, we employed these nanorattles in proof-of-concept UC-monitoring drug release by utilizing the energy transfer process from UC fluorides to DOX, thus revealing the great potential of the nanorattles as efficient cancer theranostic agent.

Blue-LED-excitable NIR-Ⅱluminescent lanthanide-doped SrS nanoprobes for ratiometric thermal sensing

Lanthanide(Ln^(3+))-doped near infrared(NIR)-II luminescent nanoprobes have shown great promise in many technological fields,but are currently limited by the low absorption efficiency of Ln^(3+)due to the forbidden 4f→4f transition.Herein,we report a novel NIR-II luminescent nanoprobe based on efficient energy transfer from Ce^(3+)to Er^(3+)and Nd^(3+)in sub-10 nm SrS nanocrystals(NCs),which are excitable by using a commercial blue light-emitting diode(LED).Through sensitization by the allowed 4f→5d transition of Ce^(3+),the NCs exhibit strong NIR-II luminescence from Er^(3+)and Nd^(3+)with quantum yields of 2.9%and 2.3%,respectively.Furthermore,by utilizing the intense NIR-II luminescence of Er^(3+)from the thermally coupled Stark sublevels of ^(4)I_(13/2),we demonstrate the application of SrS:Ce^(3+)/Er^(3+)NCs as blue-LED-excitable NIR-II luminescent nanoprobes for ratiometric thermal sensing.These findings reveal the unique advantages of SrS:Ln^(3+)NCs in NIR-II luminescence,which may open up a new avenue for exploring novel and versatile luminescent nanoprobes based on Ln^(3+)-doped sulphide NCs.

Mn^(2+)-activated calcium fluoride nanoprobes for time-resolved photoluminescence biosensing

Time-resolved (TR)photoluminescence (PL) technique has shown great promise in ultrasensitive biodetection and high-resolution bioimaging.Hitherto,almost all the TRPL bioprobes are based on the parity-forbidden f→f transition of lanthanide ions.Herein,we report TRPL biosensing by taking advantage of the d→d transition of transition metal (TM)Mn^2+ ion.We demonstrate that the Forster resonance energy transfer (FRET)signal can be distinguished from that of radiative reabsorption process through measuring the PL lifetime of Mn^2+,thus establishing a reliable method for Mn^2+ in homogeneous TR-FRET biodetection.We also demonstrate the biotin receptor-targeted cancer cell imaging by utilizing biotinylated CaF2:Ce,Mn nanoprobes.Furthermore,we show in a proof-of-concept experiment the appli- cation of the long-lived PL of Mn^2+ for TRPL bioimaging through the burst shot with a cell phone.These findings provide a general approach for exploiting the long-lived PL of TM ions for TRPL biosensing,thereby opening up a new avenue for the exploration of novel and versatile applications of TM ions.

Boosting the Energy Migration Upconversion through Inter-Shell Energy Transfer in Tb^(3+)-Doped Sandwich Structured Nanocrystals

It remained challenging to fabricate Tb^(3+)-doped lanthanide nanocrystals(NCs)to simultaneously acquire strong energy migration upconversion(EMU)emissions of Tb^(3+)while suppressing the Tm3+UV upconversion emissions that cause background biofluorescence issues in bioapplications based on Tb^(3+)-doped EMU NCs.Herein,we report a novel sandwich structured core@shell@shell scheme for the design of EMU NCs,for example,NaLuF4∶Yb/Gd@NaGdF4∶Tm@NaLuF4∶Tb NCs,wherein Yb^(3+),Tm^(3+),and Tb^(3+)are incorporated separately into the inner core,middle shell,and outer shell,respectively.We found that in the sandwich structured NCs,the effective inter-shell energy transfer from Gd^(3+)in the middle shell to Tb^(3+)in the outer shell accelerated the Yb^(3+)-Tm^(3+)five-photon upconversion and the subsequent Tm^(3+)to Gd^(3+)energy transfer processes,which could eventually lead to almost complete inhibition of Tm^(3+)UV upconversion emissions,concurrent with the strong EMU emissions of Tb^(3+).Our findings might stimulate new concepts for manipulating upconversion emissions of lanthanide NCs.