Reversible Release and Fixation of Bromine in Vacancy-Ordered Bromide Perovskites

Bromine is an irreplaceable reagent for many important applications including necessary additive for flame retardants and rubber treatment.However,the toxicity,causticity,and vaporability of bromine make the safe usage and transportation of bromine challenging,which can be alleviated by the bromine prefixation.Herein,vacancy-ordered bromide perovskites such as Cs^(4)Sb_(2)Br_(12)and Cs_(2)PdBr_(6)are selected out for the bromine fixation through density-functional theory calculations and experiments.The redox within the bromide perovskites is designed to provide the driving force for the reversible release and fixation of bromine.Heating and cooling the title bromide perovskites in a necked ampoule make the bromine visible and separable from the solid residue.The composition engineering(i.e.,Cs_(4)Sb_(2)Br_(12)vs Rb_(4)Sb_(2)Br_(12),and Cs_(4)Sb_(2)Br_(12)vs Cs_(2)PdBr_(6))can effectively tune the stability(against water and high temperature)and the bromine storage capacity(from9.30%to 18.76%).In addition,this work can provide a one-step preparation method for the liquid bromine without further purification.

Solution-Processed Hybrid Europium (Ⅱ) lodide Scintillator for Sensitive X-Ray Detection

Lead halide perovskite nanocrystals have recently demonstrated great potential as x-ray scintillators,yet they stll suffer toxicity issues,inferior light yield(LY)caused by severe self-absorption.Nontoxic bivalent europium ions(Eu^(2+))with intrinsically efficient and self-absorption-free d-f transition are a prospective replacement for the toxic Pb^(2+).Here,we demonstrated solution-processed organic-inorganic hybrid halide BA_(10)Eul_(12)(BA denotes C_(4)H_(9)NH_(4)^(+))single crystals for the first time.

Material exploration via designing spatial arrangement of octahedral units: a case study of lead halide perovskites

Halide perovskites have attracted tremendous attention as semiconducting materials for various optoelectronic applications.The functional metal-halide octahedral units and their spatial arrangements play a key role in the optoelectronic properties of these materials.At present,most of the efforts for material exploration focus on substituting the constituent elements of functional octahedral units,whereas designing the spatial arrangement of the functional units has received relatively little consideration.In this work,via a global structure search based on density functional theory(DFT),we discovered a metastable three-dimensional honeycomb-like perovskite structure with the functional octahedral units arranged through mixed edge-and comer-sharing.We experimentally confirmed that the honeycomb-like perovskite structure can be stabilized by divalent molecular cations with suitable size and shape,such as 2,2’-bisimidazole(BIM).DFT calculations and experimental characterizations revealed that the honeycomb-like perovskite with the formula of BIMPb2l6,synthesized through a solution process,exhibits high electronic dimensionality,a direct allowed bandgap of 2.1 eV,small effective masses for both electrons and holes,and high optical absorption coefficients,which indicates a significant potential for optoelectronic applications.The employed combination of DFT and experimental study provides an exemplary approach to explore prospective optoelectronic semiconductors via spatially arranging functional units.

Antimony doped Cs2SnCl6 with bright and stable emission

Lead halide perovskites,with high photoluminescence efficiency and narrow・band emission,are promising materials for display and lighting.However,the lead toxicity and environmental sensitivity hinder their potential applications.Herein,a new antimony・doped lead-free inorganic perovskites variant Cs2SnCl6:xSb is designed and synthesized.The perovskite variant Cs2SnCl6:xSb exhibits a broadband orange-red emission,with a photoluminescence quantum yield(PLQY)of 37%.The photoluminescence of Cs2SnCl6:xSb is caused by the ionoluminescence of Sb3+within Cs2SnCl6 matrix,which is verified by temperature dependent photoluminescence(PL)and PL decay measurements.In addition,the all inorganic structure renders Cs2SnCl6:xSb with excellent thermal and water stability.Finally,a white light-emitting diode(white-LED)is fabricated by assembling Cs2SnCl6:0.59%Sb,Cs2SnCl6:2.75%Bi and Ba2Sr2SiO4:Eu2+onto the commercial UV LED chips,and the color rendering index(CRI)reaches 81.

Identifying quasi-2D and 1D electrides in yttrium and scandium chlorides via geometrical identification

Developing and understanding electron-rich electrides offers a promising opportunity for a variety of electronic and catalytic applications.Using a geometrical identification strategy,here we identify a new class of electride material,yttrium/scandium chlorides Y(Sc)_(x)Cl_(y)(yx<2).Anionic electrons are found in the metal octahedral framework topology.The diverse electronic dimensionality of these electrides is quantified explicitly by quasi-two-dimensional(2D)electrides for[YCl]^(+)∙e−and[ScCl]^(+∙)e−and one-dimensional(1D)electrides for[Y_(2)Cl_(3)]^(+)∙e−,[Sc_(7)Cl_(10)]^(+)∙e−,and[Sc5Cl8]2+∙2e−with divalent metal elements(Sc^(2+):3d^(1) and Y^(2+):4d^(1)).The localized anionic electrons were confined within the inner-layer spaces,rather than inter-layer spaces that are observed in A_(2)B-type 2D electrides,e.g.Ca_(2)N.Moreover,when hydrogen atoms are introduced into the host structures to form YClH and Y2Cl3H,the generated phases transform to conventional ionic compounds but exhibited a surprising reduction of work function,arising from the increased Fermi level energy,contrary to the conventional electrides reported so far.Y_(2C)l_(3) was experimentally confirmed to be a semiconductor with a band gap of 1.14 eV.These results may help to promote the rational design and discovery of new electride materials for further technological applications.