钙钛矿型复合氧化物气敏材料的研究进展

钙钛矿型气敏材料由于具有稳定的晶体结构和良好的热稳定性,越来越引起人们的重视.介绍了钙钛矿型复合氧化物的结构,综述了钙钛矿型复合氧化物(ABO3)的气敏性质以及在气敏方面的研究应用进展.并对今后的研究方向进行了展望.     

钙钛矿型复合氧化物的研究与应用进展

从钙钛矿型复合氧化物的晶体结构及电子结构出发,分析了其结构与性能的构效关系,综述了钙钛矿型复合氧化物的特性与制备方法以及国内外应用的研究现状.     

Size and Shape Exclusion in 2D Silicon Dioxide Membranes

2D membranes such as artificially perforated graphene are deemed to bring great advantages for molecular separation. However, there is a lack of structure-property correlations in graphene membranes as neither the atomic configurations nor the number of introduced sub-nanometer defects are known precisely. Recently, bilayer silica has emerged as an inherent 2D membrane with an unprecedentedly high areal density of well-defined pores. Mass transfer experiments with free-standing SiO₂ bilayers demonstrated a strong preference for condensable fluids over inert species, and the measured membrane selectivity revealed a key role of intermolecular forces in ångstrom-scale openings. In this study, vapor permeation measurements are combined with quantitative adsorption experiments and density functional theory (DFT) calculations to get insights into the mechanism of surface-mediated transport in vitreous 2D silicon dioxide. The membranes are shown to exhibit molecular sieving performance when exposed to vaporous methanol, ethanol, isopropanol, and tert-butanol. The results are normalized to the coverage of physisorbed molecules and agree well with the calculated energy barriers.     

凝胶渗透色谱-多角度激光散射测定聚乙二醇分子量

以一种低分子量的聚乙二醇为例,对凝胶渗透色谱-多角度激光散射法的测试原理及影响因素进行了分析。研究发现,在测定齐聚物分子量时,适当提高进样浓度有利于减少测试误差,且dn/dc值随分子量的变化对测试结果影响不大,按示差峰出峰时间和激光峰的收峰时间确定有效峰面积,以及在激光信号最强的Debye图中通过去掉偏离直线较远的点后外推θ至0°所得到的测试结果误差均较小。     

Au-MgF2复合纳米颗粒薄膜的制备和微结构

用射频磁控共溅射法制备了Au体积分数分别为6%、15%、25%、40%、50%和60%的Au-MgF2复合纳米颗粒薄膜.用X射线衍射、透射电镜、X射线光电子能谱对薄膜的微结构和组分进行了测试分析,分析结果表明:制备的Au-MgF2复合纳米颗粒薄膜由fcc-Au晶态纳米微粒镶嵌于主要为非晶态的MgF2陶瓷基体中构成,当Au体积百分含量由15%增至60%时,其平均晶粒尺寸由5.1nm增大到21.2 nm,晶格常数由0.399 84nm增大到0.407 43nm;随Au体积百分含量由6%增至50%,其颗粒平均粒径则由9.8nm增至21.4 nm.名义组分为vol.60%Au-MgF2样品中Au的体积百分含量约为62.6%,与设计值基本一致.     

Controlling Nucleation and Growth of Metal Halide Perovskite Thin Films for High‐Efficiency Perovskite Solar Cells

Metal halide perovskite thin films can be crystallized via a broad range of solution‐based routes. However, the quality of the final films is strongly dependent upon small changes in solution composition and processing parameters. Here, this study demonstrates that a fractional substitution of PbCl₂ with PbI₂ in the 3CH₃NH₃I:PbCl₂ mixed‐halide starting solution has a profound influence upon the ensuing thin‐film crystallization. The presence of PbI₂ in the precursor induces a uniform distribution of regular quadrilateral‐shaped CH₃NH₃PbI₃ perovskite crystals in as‐cast films, which subsequently grow to form pinhole‐free perovskite films with highly crystalline domains. With this new formulation of 3CH₃NH₃I:0.98PbCl₂:0.02PbI₂, this study achieves a 19.1% current–voltage measured power conversion efficiency and a 17.2% stabilized power output in regular planar heterojunction solar cells.     

High‐Resolution Spin‐on‐Patterning of Perovskite Thin Films for a Multiplexed Image Sensor Array

Inorganic–organic hybrid perovskite thin films have attracted significant attention as an alternative to silicon in photon‐absorbing devices mainly because of their superb optoelectronic properties. However, high‐definition patterning of perovskite thin films, which is important for fabrication of the image sensor array, is hardly accomplished owing to their extreme instability in general photolithographic solvents. Here, a novel patterning process for perovskite thin films is described: the high‐resolution spin‐on‐patterning (SoP) process. This fast and facile process is compatible with a variety of spin‐coated perovskite materials and perovskite deposition techniques. The SoP process is successfully applied to develop a high‐performance, ultrathin, and deformable perovskite‐on‐silicon multiplexed image sensor array, paving the road toward next‐generation image sensor arrays.     

Fabrication of Transistors on Flexible Substrates: from Mass‐Printing to High‐Resolution Alternative Lithography Strategies

In this report, the development of conventional, mass‐printing strategies into high‐resolution, alternative patterning techniques is reviewed with the focus on large‐area patterning of flexible thin‐film transistors (TFTs) for display applications. In the first part, conventional and digital printing techniques are introduced and categorized as far as their development is relevant for this application area. The limitations of conventional printing guides the reader to the second part of the progress report: alternative‐lithographic patterning on low‐cost flexible foils for the fabrication of flexible TFTs. Soft and nanoimprint lithography‐based patterning techniques and their limitations are surveyed with respect to patterning on low‐cost flexible foils. These show a shift from fabricating simple microlense structures to more complicated, high‐resolution electronic devices. The development of alternative, low‐temperature processable materials and the introduction of high‐resolution patterning strategies will lead to the low‐cost, self‐aligned fabrication of flexible displays and solar cells from cheaper but better performing organic materials.     

银钠米粒子/二氧化钛复合薄膜的溶胶凝胶法制备及其光学性质的研究

用溶胶凝胶法制备了含纳米级银粒子的TiO2 薄膜。对薄膜进行了XRD、TEM、XPS等测试 ,发现空气中 60 0 - 80 0℃热处理形成了含 4 - 4 5nm的Ag金属粒子的锐钛矿和金红石多晶薄膜。Ag微粒子随热处理温度升高而增长。这些薄膜在可见光区有一个较宽的吸收峰。     

Endowing Perovskite Nanocrystals with Circularly Polarized Luminescence

Perovskite nanocrystals are attracting great interest due to their excellent photonic properties. Here, through a supramolecular self‐assembly approach, the perovskite nanocrystals (NCs) with a novel circularly polarized luminescence (CPL) are successfully endowed. It is found that the achiral perovskite NCs can coassemble with chiral gelator in nonpolar solvents, in which the gelator molecules modify the surface of the perovskite NCs. Through such cogelation, the molecular chirality can transfer to the NCs resulting in CPL signals with a dissymmetric factor (g_lum) up to 10^?3. Furthermore, depending on the molecular chirality of the gelator, the CPL sense can be selected and the mirror‐imaged CPL is obtained. Such gels can be further embedded into the polymer film to facilitate flexible CPL devices. It is envisaged that this approach will afford a new insight into the designing of the functional chiroptical materials.     

Morphology Control of Doped Spiro‐MeOTAD Films for Air Stable Perovskite Solar Cells

Doped 2,2′,7,7′‐tetrakis(N,N‐di‐p‐methoxyphenylamine)‐9,9′‐spirobifluorene (spiro‐MeOTAD), which acts as a hole‐transporting layer (HTL), endows perovskite solar cells (PSCs) with excellent performance. However, the intrinsically hygroscopic nature of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) dopants also aggravates the moisture instability of PSCs. In this work, the origins of the moisture instability of spiro‐MeOTAD HTLs are explored and strategies to enhance moisture resistance are proposed. After 780 h of aging in air, 52% of the initial power conversion efficiency (PCE) can be sustained by prolonging the mixing time of the precursor solution of spiro‐MeOTAD to reduce accumulated LiTFSI. In contrast, only 7% of the initial PCE remains if the precursor solution is mixed briefly. By thermally annealing an HTL to evaporate residual tBP in spiro‐MeOTAD, pinholes are completely eliminated and 65% of the initial PCE remains after the same aging time. In this study, the significance of the initial morphology of spiro‐MeOTAD HTLs on device stability is analyzed and strategies based on physical morphology for controlling PSC moisture instability induced by HTL dopants are developed.     

钙钛矿/钨青铜两相复合BSTN陶瓷的形成与性能研究

设计了特殊配方0.7BaO.0.3SrO·(1-y)TiO₂·yNb₂O₅, 通过过量组成控制,制备了钙钛矿相和钨青铜相共存的复相陶瓷.用XRD和阻抗仪测试了相结构及介电常数.结果表明,在形成以钙钛矿为主相的体系中,Nb₂O₅过量6mol％以上时开始形成钨青铜相;在形成以钨青铜为主相的体系中,BaO和SrO过量11mol％以上时开始形成钙钛矿相.两相含量相当的体系中,钙钛矿相几乎不固溶Nb₂O₅,而钨青铜相固溶一定量TiO₂.复相陶瓷的介电性能具有BST和SBN两相的特点.BSTN复相体系中钨青铜相的铁电/顺电转变温度随固溶TiO₂量增加而降低,随钙钛矿相增加而升高,其最低转变温度约在200℃,比纯SBN相下降90℃.     

High‐Performance Flexible Photodetectors based on High‐Quality Perovskite Thin Films by a Vapor–Solution Method

Organometal halide perovskites are new light‐harvesting materials for lightweight and flexible optoelectronic devices due to their excellent optoelectronic properties and low‐temperature process capability. However, the preparation of high‐quality perovskite films on flexible substrates has still been a great challenge to date. Here, a novel vapor–solution method is developed to achieve uniform and pinhole‐free organometal halide perovskite films on flexible indium tin oxide/poly(ethylene terephthalate) substrates. Based on the as‐prepared high‐quality perovskite thin films, high‐performance flexible photodetectors (PDs) are constructed, which display a nR value of 81 A W^?1 at a low working voltage of 1 V, three orders higher than that of previously reported flexible perovskite thin‐film PDs. In addition, these flexible PDs exhibit excellent flexural stability and durability under various bending situations with their optoelectronic performance well retained. This breakthrough on the growth of high‐quality perovskite thin films opens up a new avenue to develop high‐performance flexible optoelectronic devices.     

High‐Performance Blue Perovskite Light‐Emitting Diodes Enabled by Efficient Energy Transfer between Coupled Quasi‐2D Perovskite Layers

While there has been extensive investigation into modulating quasi‐2D perovskite compositions in light‐emitting diodes (LEDs) for promoting their electroluminescence, very few reports have studied approaches involving enhancement of the energy transfer between quasi‐2D perovskite layers of the film, which plays very important role for achieving high‐performance perovskite LEDs (PeLEDs). In this work, a bifunctional ligand of 4‐(2‐aminoethyl)benzoic acid (ABA) cation is strategically introduced into the perovskite to diminish the weak van der Waals gap between individual perovskite layers for promoting coupled quasi‐2D perovskite layers. In particular, the strengthened interaction between coupled quasi‐2D perovskite layers favors an efficient energy transfer in the perovskite films. The introduced ABA can also simultaneously passivate the perovskite defects by reducing metallic Pb for less nonradiative recombination loss. Benefiting from the advanced properties of ABA incorporated perovskites, highly efficient blue PeLEDs with external quantum efficiency of 10.11% and a very long operational stability of 81.3 min, among the best performing blue quasi‐2D PeLEDs, are achieved. Consequently, this work contributes an effective approach for high‐performance and stable blue PeLEDs toward practical applications.