Plasmonic CsPbBr_(3)–Au nanocomposite for excitation wavelength dependent photocatalytic CO_(2) reduction

The optoelectronic performance of CsPbBr_3 nanocrystal(NC) has been dramatically limited by the severe charge carrier recombination and its narrow light absorption range,which are anticipated to be resolved via coupling with plasmonic Au nanoparticle(NP).In view of this,CsPbBr_3-Au nanocomposite is fabricated and further employed as a concept model to study the electronic interaction between perovskite NC and Au NP for the first time.It has been found that the excitation-wavelength dependent carrier transfer behavior exists in CsPbBr_3-Au nanocomposite.Upon illumination with visible light(λ>420 nm),photo-generated electrons in CsPbBr_3 can inject into Au with an electron injection rate and efficiency of 2.84×10~9 s^(-1) and 78%,respectively.The boosted charge separation is further translated into a 3.2-fold enhancement in CO_2 photocatalytic reduction activity compared with pristine CsPbBr_3.On the other hand,when solely exciting Au NP with longer wavelength light(λ>580 nm),the localized surface plasmon resonance(LSPR) induced hot electrons in Au NPs can transfer to CsPbBr_3 NC and further participate in photocatalytic reaction towards CO_2 reduction.The present study provides new insights into preparing plasmonic nanostructure to enhance the performance of perovskite based optoelectronic devices.

Layered-stacking of titania films for solar energy conversion:Toward tailored optical,electronic and photovoltaic performance

Nanostructured TiO2 with differentiate morphologies has attracted tremendous attention due to its wide band-gap nature as well as outstanding optical and electric properties for solar-driven light-toelectricity conversion application. Layered-stacking TiO2 film such as double-layer, tri-layer, quadrupleor quintuplicate-layer, is highly desirable to the design of high-performance semiconductor material photoanodes and the development of advanced photovoltaic devices. In this minireview, we will summarize the recent progress and achievements on proof-of-concept of layered-stacking TiO2 films（LTFs） for solar cells with emphasis on the tailored properties and synergistic functionalization of LTFs, such as optimized sensitizer adsorption, broadened light confinement as well as facilitated electron transport characteristics.Various demonstrations of LTFs photovoltaic systems provide lots of possibilities and flexibilities for more efficient solar energy utilization that a wide variety of TiO2 with distinguished morphologies can be integrated into differently structured photoanodes with synergistic and complementary advantages. This key structure engineering technology will also pave the way for the development of next generation state-ofthe-art electronics and optoelectronics. Finally, from our point of view, we conclude the future research interest and efforts for constructing more efficient LTFs as photoelectrode, which will be highly warranted to advance the solar energy conversion process.

Can the efficiencies of simplified perovskite solar cells go higher?

In recent years, metal halide perovskites have emerged as star semiconducting materials in the field of optoelectronic devices owing to their fascinating optoelectronic properties. Of particular interest are perovskite solar cells (PSCs), which have witnessed skyrocketing power conversion efficiencies (PCEs) within a short period of time, and were recently certified to reach 25.5%, which is already higher than other thin film photovoltaic technologies[1]. Nevertheless, multiple layers are still needed for state-of-theart PSCs to achieve high PCEs over 21%.

Te^(4+)掺杂Cs_(2)InCl_(5)·H_(2)O单晶的光学测温应用

本文设计合成了一种Te^(4+)离子掺杂的Cs_(2)InCl_(5)·H_(2)O单晶,该单晶在紫外光激发下发射明亮橙光.未掺杂的Cs_(2)InCl_(5)·H_(2)O单晶几乎没有发光现象,但Te^(4+)掺杂的Cs_(2)InCl_(5)·H_(2)O单晶,发射峰位于660 nm,并伴随着大的Stokes位移和宽的发光半峰宽(180 nm).结合变温荧光光谱以及飞秒瞬态吸收光谱等表征,揭示了其发光机理为自陷激子发光.零维结构中的强电声耦合以及软晶格有利于形成并稳定自陷激子.特别地,由于Te^(4+)离子的最外层电子结构为5s^(2),对温度变化较为灵敏,Te^(4+)离子掺杂的Cs_(2)InCl_(5)·H_(2)O单晶的发光寿命表现出了非常强的温度依赖性,发光寿命从80 K下的6μs缩短至380 K下的19 ns,320 K处的相对灵敏度达到0.062 K^(-1),可以与传统稀土基光学测温材料相媲美.据我们所知,这是首次将铟基金属卤化物钙钛矿单晶应用于光学测温,将为设计合成新型多功能响应的金属卤化物钙钛矿发光材料提供借鉴意义.

构建三元WO_(3)/CsPbBr_(3)/ZIF-67异质结用于高效光催化CO_(2)还原

近年来,卤素钙钛矿纳米材料以其优异的光电性能在光催化等领域引起了关注.然而,光生载流子严重的复合反应和较差的反应动力学也极大地限制了其光催化性能.本论文设计合成了一种三元WO_(3)/CsPbBr_(3)/ZIF-67异质光催化剂,并将其应用于有效的CO_(2)光还原反应.研究表明,WO_(3)与CsPbBr_(3)之间构建的Z型电荷转移路径能够保证光生载流子的有效转移和分离.此外,在表面修饰具有活性Co中心的ZIF-67壳层作为助催化剂有利于改善复合材料的CO_(2)的吸附和活化能力.因此,电荷分离和CO_(2)吸附性能的增强大大提高了WO_(3)/CsPbBr_(3)/ZIF-67的光催化活性,还原产物中CO产率达到99.38μmol g_(−1),是单一CsPbBr_(3)的6.8倍.这项工作有望为开发高效的卤素钙钛矿基光催化剂及其在CO_(2)还原和其他复杂光催化反应中的应用提供参考.

A facile method to fabricate high-quality perovskite nanocrystals based on single crystal powder

Although great advancements have been successfully achieved in ligand-assisted reprecipitation strategy(LARP)towards lead halide perovskite nano crystals(NCs)syn thesis,it still remains challe nging to develop bright and stable iodide-based perovskite NC via facile LARP.Herein,striki ngly bright MAPbl3 NCs with photoluminesce nee qua ntum yield(PLQY)as high as 79%are synthesized via replacing the raw material(MAI and Pbh)with MAPbl3 crystal powder during LARP procedure.It has been found that crystal powder derived MAPbl3 NCs are more iodide-rich compared with that based on raw material,which is favorable to passivate the surface trap state.Accordingly,femtosecond transient absorption spectroscopies and space charge limited current measurements have corroborated that the trap density is much less in crystal powder resulted MAPbl3 NCs.Further analyses indicate stronger solvation with reduced precursor colloid size has been observed in crystal powder derived precursor solution probably due to the formation of MAPbl3-DMF.This work has provided a facile but valid method to enhance the photoluminesce nee of perovskite NC via modulati ng the beginning precursor solution.

Full-color-tunable phosphorescence of antimony-doped lead halide single crystal

Although multiple emissive phosphors are of great fundamental interest and practical importance,it is still challenging to achieve full-color tunable luminescence in a single-component material.Herein,we present an antimony-doped lead halide single crystal(C10NH22)2PbBr4:Sb3+with widely tunable red/green/blue/white luminescence.Extrinsic Sb3+dopants provide host another active sites to capture photo-generated excitons,thus triggering blue/red dual emission.Moreover,a reversible thermal-induced phase transition transforms blue/red emission into green/red dual emission.Both two phases exhibit intriguing excitation-wavelength dependent emission,affording a whole color gamut covering the red-green-blue(RGB)color triangle on the CIE 1931 diagram.Experimental and theoretical calculation studies reveal two emitters work independently,which paves the way for the multimode optical control and promotes the development of multifunctional luminescent materials.