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1.
Chiwon Kang Jung-Hyun Park Dongna Shen Hosang Ahn Minseo Park Dong-Joo Kim 《Journal of Sol-Gel Science and Technology》2011,58(1):85-90
(K0.5 Na0.5)NbO3 (KNN) perovskite materials have been developed as a promising lead-free piezoelectric material for environmentally benign
piezoelectric devices. KNN films with about 320 nm thickness were fabricated on Pt(111)/SiO2/Si(100) substrates by a sol–gel method from stoichiometric and A-site ion excess precursor solutions. Two different annealing
methods were also used to investigate the crystallographic evolution of the films. A layer-by-layer annealing process results
in highly (001) oriented KNN from the annealing temperature of 550 °C, while the final annealing method leads to weaker crystalline
peaks with a random orientation. The KNN films from the K and Na excess precursor solutions show similar crystallization behavior.
However, the ferroelectric hysteresis loops of the films were greatly improved by compensating for an A-site vacancy. In particular,
the KNN films from K-excess precursor solutions show better ferroelectric properties compared to the films prepared from Na
excess solutions. 相似文献
2.
Lead-free halide perovskite nanocrystals (NCs) represent a group of emerging materials which hold promise for various optical and optoelectronic applications. Exploring facile synthetic methods for such materials has been of great interest to not only fundamental research but also technological implementations. Herein, we report a fundamentally new method to access lead-free Bi-based double perovskite (DP) and quadruple perovskite (or layered double perovskite, LDP) NCs based on a post-synthetic transformation reaction of Cs3BiX6 (X = Cl, Br) zero-dimensional (0D) perovskite NCs under mild conditions. The produced NCs show good particle uniformity, high crystallinity, and comparable optical properties to the directly synthesized NCs. The relatively slow kinetics and stop-on-demand feature of the transformation reaction allow real-time composition–structure–property investigations of the reaction, thus elucidating a cation-alloyed intermediate-assisted transformation mechanism. Our study presented here demonstrates for the first time that post-synthetic transformation of 0D perovskite NCs can serve as a new route towards the synthesis of high-quality lead-free perovskite NCs, and provides valuable insights into the crystal structures, excitonic properties and their relationships of perovskite NCs.Lead-free perovskite nanocrystals are synthesized by post-synthetic transformation reactions. The post-synthetic transformations show the structural flexibility of zero-dimensional perovskite nanocrystal materials. 相似文献
3.
The discovery of new environmentally friendly luminescent materials with high photoluminescence quantum yield and long-term stability is critical for future solid-state lighting and displays applications. Although lead halide perovskite materials with excellent optical properties have been extensively investigated in recent years because they hold tremendous promise in optoelectronic devices, the toxicity of lead and poor air-stability still hinder their commercial applications. Moreover, while substantial work has been done on three-dimensional (3D) perovskite halides, the zero-dimensional (0D) halide emitters with bright luminescence remain elusive. Herein we report a facile solid-state reaction method to prepare an efficient lead-free all-inorganic halide material with 0D structure, Cs3Cu2I5, with photoluminescence quantum yield up to 80%. Under ultraviolet excitation at 313 nm, the Cs3Cu2I5 powder phosphors show a strong blue photoluminescence emission with peak at 445 nm and CIE color coordinates of (0.1486, 0.0873). Notably, Cs3Cu2I5 exhibits good color stability at high temperatures and outstanding stability towards air exposure exceeding one month (30 days). These findings not only open up a door for the development of promising highly emissive low-dimensional halide materials for lighting and displays, but also offer a new scalable approach for the potential mass production of halide emitters. 相似文献
4.
《Solid State Sciences》2012,14(2):225-228
The perovskite PrFeO3 ceramics were synthesized via sol–gel method. The dielectric properties and impedance spectroscopy (IS) of these ceramics were studied in the frequency range from 100 Hz to 1000 kHz in the temperature range from 80 K to 300 K. These materials exhibited colossal dielectric constant value of ∼104 at room temperature. The response is similar to that observed for relaxorferroelectrics. IS data analysis indicates the ceramics to be electrically heterogeneous semiconductor consisting of semiconducting grains with dielectric constant 30 and more resistive grain boundaries with effective dielectric constant ∼104. We conclude, therefore that grain boundary effect is the primary source for the high effective permittivity in PrFeO3 ceramics. 相似文献
5.
Powerful tools like Differential Scanning Calorimetry (DSC) and DTA seem to be under-utilized for the emerging materials for high temperature piezoelectric sensors, while thermal aspects of such piezoelectric phase change are also of theoretical interest. Curie temperature of Lead Meta-Niobate (PbNb2O6 or PN) is 570 °C, much higher than that for widely used lead zirconate titanate, making PN potentially more attractive at high temperatures. However, the only specific heat measurement for PN appears to be the 2–25 K study by Lawless, leaving the Curie temperature region unexplored. For PN, piezoelectricity is possible for the meta-stable orthorhombic structure only. So, we prepared pure phase orthorhombic PN by quenching (Q) and the rhombohedral PN by slow-cooling (S). We report for the first time, to our knowledge, DSC across the Curie temperature for Q and S types of PN. We find clear and interesting DSC signals at the Curie temperature in heating and cooling graphs for quenched (Q) PbNb2O6 only and none for the slow-cooled (S) PbNb2O6. 相似文献
6.
《中国化学快报》2023,34(8):107980
Chiral organic-inorganic metal halide semiconductors (OIMHSs) have recently attracted numerous interests due to their unique chirality, structural tunability, and extensive physical properties. However, most reported chiral OIMHSs contain toxic lead, which will be a potential obstacle to their further applications. Herein, we successfully synthesized a novel chiral lead-free tin(IV)-based OIMHS [(R)-3-hydroxyquinuclidinium]2SnCl6 ([R-HQ]2SnCl6). It exhibits a wide band gap (Eg) of about 4.11 eV. Moreover, [R-HQ]2SnCl6 undergoes a phase transition around 330 K (Tc) and shows distinct dielectric switching characteristics with good repeatability. This work enriches the chiral lead-free OIMHS family and stimulates further exploration of chiral lead-free OIMHS switching materials 相似文献
7.
《Comptes Rendus de l''Academie des Sciences Series IIB Mechanics Physics Astronomy》2001,4(3):189-192
Electron magnetic resonance (EMR) studies of intercalation ferromagnet 2, 2’-bipyridine-MnPS3 (Tc = 40 K) in the temperature range 300–14 K have revealed many interesting features across the (magnetic) order–disorder transition. The exchange narrowed line in the paramagnetic phase exhibited sudden reduction in its intensity concomitant with a g-shift to lower values (line shifted to higher fields) and increased line width. These changes took place in the 40–25 K range. In the 25–22 K range of temperature, the paramagnetic line disappeared and the FMR signal appeared at lower fields. It is significant that two closely lying FMR signals appeared in the magnetically ordered regime, suggesting the possibility of existence of two different Mn-sites having different g-values, in this state. This may be responsible for the reported magnetic moments values of less than 5.9 BM from bulk magnetisation studies. 相似文献
8.
《Helvetica chimica acta》2017,100(7)
Methylammonium lead trihalide perovskite solar cells (CH3NH3PbY3, where Y = I(3 − x )Brx = 1 – 3, I(3 − x )Clx = 1 – 3, Br(3 − x )Clx = 1 – 3, and IBrCl) are photonic semiconducting materials. Researches on various fundamental and technological aspects of these materials are extensively on‐going to make them stable environmentally and for commercialization. Research studies addressing these materials as organometallic are massively and repeatedly appearing in reputable and high‐profile peer‐reviewed journal publications (viz . Energy and Environmental Science , Nature Chemistry , Nature Communication , Advanced Materials , Science , ACS Nano , ACS Energy Letters , and in many other chemistry and materials based international journals). Herein, I candidly addresses the question: whether should scientists in the perovskite and nanomaterials science communities refer CH3NH3PbY3, as well as other perovskite derivatives falling into the same category, as organometallic? 相似文献
9.
Qiang-Qiang Jia Liang Tong Prof. Dr. Wan-Ying Zhang Prof. Dr. Da-Wei Fu Prof. Dr. Hai-Feng Lu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(40):e202200579
Hybrid organic-inorganic perovskite (HOIP) have received tremendous scientific attention because of the phase transition and photovoltaic properties. However, achieving the special perovskite structure with both two-step dielectric response and luminescence characteristics is rarely reported. Herein, we report an organic-inorganic hybrid perovskite, [(BA)2 ⋅ PbI4] (Compound 1, BA=n-butylamine) by introducing flexible organic cations (HBA+), with direct mid-band gap as 2.28 eV. Interestingly, this material exhibits two-step reversible dielectric response at 350 K and 460 K (in heating process), respectively. Besides, the photoluminescence was found: it emits charming green light under 365 nm lamp (Photoluminescence quantum yield is 9.52 %). The outstanding two-step dielectric response and luminescence characteristics of this compound might pave the way for the application of dielectric and ferroelectric functional materials in temperature sensors and mechanical switches. 相似文献
10.
《Journal of solid state chemistry》2004,177(4-5):1157-1164
The doubled perovskite structure (2ap, 2ap, 2ap) of the fast ionic conductor Li0.18La0.61TiO3 was investigated between 5 and 773 K by powder neutron diffraction. The Rietveld refinement of this orthorhombic (Cmmm Space Group) perovskite showed that at low temperature, La and vacancy rich planes alternate along [001] direction, and TiO6 octahedra were out-of-phase tilted around the b-axis. As temperature increased, the octahedral tilting decreased and the structure approaches, at about 773 K, that of the tetragonal phase, a, ap, 2ap (P4/mmm Space Group). In the temperature range of the study, the La-vacancy distribution remained unchanged, but LaO12 cuboctahedra became more regular. In the tetragonal phase the elimination of this tilting favors the two-dimensional motion of lithium in alternate ab-planes of the perovskite. 相似文献
11.
The crystallographic defects inevitably incur during the solution processed organic‐inorganic hybrid perovskite film, especially at surface and the grain boundaries (GBs) of perovskite film, which can further result in the reduced cell performance and stability of perovskite solar cells (PSCs). Here, a simple defect passivation method was employed by treating perovskite precursor film with a hydrophobic tetra‐ammonium zinc phthalocyanine (ZnPc). The results demonstrated that a 2D‐3D graded perovskite interface with a capping layer of 2D (ZnPc)0.5MAn ? 1PbnI3n + 1 perovskite together with 3D MAPbI3 perovskite was successfully constructed on the top of 3D perovskite layer. This situation realized the efficient GBs passivation, thus reducing the defects in GBs. As expected, the corresponding PSCs with modified perovskite revealed an improved cell performance. The best efficiency reached 19.6%. Especially, the significantly enhanced long‐term stability of the responding PSCs against humidity and heating was remarkably achieved. Such a strategy in this work affords an efficient method to improve the stability of PSCs and thus probably brings the PSCs closer to practical commercialization. 相似文献
12.
Weichuan Zhang Maochun Hong Junhua Luo 《Angewandte Chemie (International ed. in English)》2020,59(24):9305-9308
Halide double perovskites have recently emerged as a promising environmentally friendly optoelectronic and photovoltaic material for their inherent thermodynamic stability, high defect tolerance, and appropriate band gaps. However, to date, no ferroelectric material based on halide double perovskites has been discovered. Herein, by hetero‐substitution of lead and cation intercalation of n‐propylamine, the first halide double perovskite ferroelectric, (n‐propylammonium)2CsAgBiBr7 ( 1 ), is reported and it exhibits distinct ferroelectricity with a notable saturation polarization of about 1.5 μC cm?2. More importantly, single‐crystal photodetectors of 1 exhibit extraordinary performance with containing high on/off ratios of about 104, fast response rates of 141 μs, and detectivity as high as 5.3×1011 Jones. This finding opens a new way to design high‐performance perovskite ferroelectrics, and provides a viable approach in the search for stable and lead‐free optoelectronic materials as an alternative to the lead‐containing system. 相似文献
13.
Alaa S. Abd-El-Aziz Maysun R. Benaaisha Mohammed S. M. Abdelbaky David Martinez-Blanco Santiago García-Granda Amani A. Abdelghani Laila H. Abdel-Rahman Rabin Bissessur 《Molecules (Basel, Switzerland)》2021,26(21)
The development of synthesis methods to access advanced materials, such as magnetic materials that combine multimetallic phosphide phases, remains a worthy research challenge. The most widely used strategies for the synthesis of magnetic transition metal phosphides (TMPs) are organometallic approaches. In this study, Fe-containing homometallic dendrimers and Fe/Co-containing heterometallic dendrimers were used to synthesize magnetic materials containing multimetallic phosphide phases. The crystalline nature of the nearly aggregated particles was indicated for both designed magnetic samples. In contrast to heterometallic samples, homometallic samples showed dendritic effects on their magnetic properties. Specifically, saturation magnetization (Ms) and coercivity (Hc) decrease as dendritic generation increases. Incorporating cobalt into the homometallic dendrimers to prepare the heterometallic dendrimers markedly increases the magnetic properties of the magnetic materials from 60 to 75 emu/g. Ferromagnetism in homometallic and heterometallic particles shows different responses to temperature changes. For example, heterometallic samples were less sensitive to temperature changes due to the presence of Co2P in contrast to the homometallic ones, which show an abrupt change in their slopes at a temperature close to 209 K, which appears to be related to the Fe2P ratios. This study presents dendrimers as a new type of precursor for the assembly of magnetic materials containing a mixture of iron- and cobalt-phosphides phases with tunable magnetism, and provides an opportunity to understand magnetism in such materials. 相似文献
14.
《Solid State Sciences》2012,14(4):445-450
A novel 3d-4f heterometallic coordination polymer, {[Tm5(μ3-OH)2(BDC)6(IN)2Cu(H2O)2]·(H2O)3}n (1) [BDC = benzene-1,2-dicarboxylate, IN = isonicotinate], has been hydrothermally synthesized and structurally characterized by single crystal X-ray diffraction, FTIR, elemental analysis, powder X-ray diffraction and thermogravimetric analysis. The compound crystallizes in monoclinic system, space group P21/c (No. 14), a = 13.7302(5) Å, b = 23.5428(3) Å, c = 21.5789(2) Å, β = 91.491(3)°, V = 6973.0(3) Å3, and Z = 4. The structure exhibits unusual two-dimensional Tm-carboxylate layer, which is constructed from the expansion of novel pentanuclear {Tm5} clusters. More interestingly, the heterometallic Cu(I) ions were successfully planted into such Ln-carboxylate layer by the bifunctional IN bridging ligands, resulting in the formation of an unprecedented 2D heterometallic lanthanide-transition-metal framework. 相似文献
15.
Sawanta S. Mali Hyungjin Kim Hyun Hoon Kim Gwang Ryeol Park Sang Eun Shim Chang Kook Hong 《Materials Today Chemistry》2017
The conventional unstable and expensive hole transporting materials (HTM) has been replaced by cost effective modified carbon hole extraction layer. Herein, we demonstrated a new recipe toward air stable and waterproof modified carbon hole extraction layer for efficient perovskite solar cells (PSCs). The commercial available carbon ink modified with methylammonium lead iodide (MAI) has been used as hole extraction layer for ambipolar perovskite solar cells. The fabricated optimized perovskite solar cell having Glass/FTO/mp-TiO2/MAPbI3-xClx/carbon + MAI/Carbon configuration exhibited η = 13.87% power conversion efficiency (PCE) with open circuit voltage (VOC) 0.997 V, current density (JSC) = 21.41 mAcm?2 and fill factor (FF) 0.65. Furthermore, the air stability were tested at room temperature in open atmosphere. The water proof stability was tested under water flushing. Our results revealed that, although our carbon based devices show lower PCE (η = 13.87%) compared to spiro-MeOTAD HTM (η = 15%), the fabricated PSCs could even retain >90% after water exposure >20 times and ambient air stability more than 160 days. Further the large area device (>1 cm2) device shows 13.04% PCE with Jsc = 21.47 mAcm?2, VOC = 0.996 V and FF = 0.61. We have also demonstrated >13% efficiency for large area device (>1.1 cm2), demonstrating that the developed method is simple, cost effective and promising towards large area device fabrication. The developed methodology based on low cost carbon hole extraction layer will be helpful towards waterproof and air stable perovskite solar cells for large-area devices. 相似文献
16.
The sol-gel processing of lead-free (Na,K) NbO3 ferroelectric films was studied. Sodium ethoxide (NaOC2H5) and potassium ethoxide (KOC2H5) were prepared by reacting solid Na and K with ethanol (99.7%) in a solvent of 2-methoxyethanol. 0.5-μm-thick (Na,K)NbO3 thin films with orthorhombic perovskite structure were obtained by pyrolyzing at 400°C and annealing at 800–900°C. The films
had relatively dense and uniform microstructure with grain size of about 50 nm, whose ferroelectricity was proved by the P-E hysteresis loop measurement. It was found that excess K was effective to reduce the annealing temperature for the crystallization
of sol-gel-derived (Na,K)NbO3 thin films. 相似文献
17.
Guo-Bin Xiao Xijiao Mu Shuyu Zhou Liu Zhu Yong Peng Qing Liang Xiaoxin Zou Jian Zhang Lei Zhang Jing Cao 《Angewandte Chemie (International ed. in English)》2023,62(17):e202303196
Typical wide-band gap cathode interlayer materials are difficulty in reducing interface recombination without limiting charge transport in perovskite solar cells (PSCs). Here, a lead-doped titanium-oxo cluster protected by S-containing ligands is introduced at the interface of perovskite and SnO2. By in situ heating, the cluster is transformed into PbSO4-PbTi3O7 heterostructure. The oxygen atoms from sulfate ion in heterostructure connect with iodine from perovskite to boost interfacial electron extraction and reduce charge recombination. While the yielded metallic interface between PbSO4 and PbTi3O7 promotes the electron transport across the interface. Finally, an efficiency as high as 24.2 % for the modified PSC is obtained. The heterostructure well-stabilize the interface of perovskite and SnO2, to greatly improve the device stability. This work provides a novel strategy to prepare wide-band gap cathode interlayer by directional transformation of heterometallic oxo clusters. 相似文献
18.
Yaobin Li Tao Yang Zhiyun Xu Xitao Liu Xiaoying Huang Shiguo Han Yi Liu Maofan Li Junhua Luo Zhihua Sun 《Angewandte Chemie (International ed. in English)》2020,59(9):3429-3433
By dimensional reduction of the 3D motif of Cs2AgBiBr6, a lead‐free 2D hybrid double perovskite, (i‐PA)2CsAgBiBr7 ( 1, i‐PA=isopentylammonium), was successfully designed. It adopts a quantum‐confined bilayered structure with alternating organic and inorganic sheets. Strikingly, the unique 2D architecture endows it highly anisotropic nature of physical properties, including electric conductivity and optical absorption (the ratio αb/αc=1.9 at 405 nm). Such anisotropy attributes result in the strong polarization‐sensitive responses with large dichroic ratios up to 1.35, being comparable to some 2D inorganic materials. This is the first study on the hybrid double perovskites with strong polarization sensitivity. A crystal device of 1 also exhibits rapid response speed (ca. 200 μs) and excellent stabilities. The family of 2D hybrid double perovskites are promising optoelectronic candidates, and this work paves a new pathway for exploring new green polarization‐sensitive materials. 相似文献
19.
Wuqian Guo Xitao Liu Shiguo Han Yi Liu Zhiyun Xu Maochun Hong Junhua Luo Zhihua Sun 《Angewandte Chemie (International ed. in English)》2020,59(33):13879-13884
Although two‐dimensional (2D) metal–halide double perovskites display versatile physical properties due to their huge structural compatibility, room‐temperature ferroelectric behavior has not yet been reported for this fascinating family. Here, we designed a room‐temperature ferroelectric material composed of 2D halide double perovskites, (chloropropylammonium)4AgBiBr8, using an organic asymmetric dipolar ligand. It exhibits concrete ferroelectricity, including a Curie temperature of 305 K and a notable spontaneous polarization of ≈3.2 μC cm?2, triggered by dynamic ordering of the organic cation and the tilting motion of heterometallic AgBr6/BiBr6 octahedra. Besides, the alternating array of inorganic perovskite sheets and organic cations endows large mobility‐lifetime product (μτ=1.0×10?3 cm2 V?1) for detecting X‐ray photons, which is almost tenfold higher than that of CH3NH3PbI3 wafers. As far as we know, this is the first study on an X‐ray‐sensitive ferroelectric material composed of 2D halide double perovskites. Our findings afford a promising platform for exploring new ferroelectric materials toward further device applications. 相似文献
20.
Wuqian Guo Xitao Liu Shiguo Han Yi Liu Zhiyun Xu Prof. Maochun Hong Prof. Junhua Luo Prof. Zhihua Sun 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(33):13983-13988
Although two-dimensional (2D) metal–halide double perovskites display versatile physical properties due to their huge structural compatibility, room-temperature ferroelectric behavior has not yet been reported for this fascinating family. Here, we designed a room-temperature ferroelectric material composed of 2D halide double perovskites, (chloropropylammonium)4AgBiBr8, using an organic asymmetric dipolar ligand. It exhibits concrete ferroelectricity, including a Curie temperature of 305 K and a notable spontaneous polarization of ≈3.2 μC cm−2, triggered by dynamic ordering of the organic cation and the tilting motion of heterometallic AgBr6/BiBr6 octahedra. Besides, the alternating array of inorganic perovskite sheets and organic cations endows large mobility-lifetime product (μτ=1.0×10−3 cm2 V−1) for detecting X-ray photons, which is almost tenfold higher than that of CH3NH3PbI3 wafers. As far as we know, this is the first study on an X-ray-sensitive ferroelectric material composed of 2D halide double perovskites. Our findings afford a promising platform for exploring new ferroelectric materials toward further device applications. 相似文献