- Efficient Exciton to Dopant Energy Transfer in Mn2+-Doped (C4H9NH3)2PbBr4 Two-Dimensional (2D) Layered Perovskites
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Three-dimensional ABX3 perovskite material has attracted immense interest and applications in optoelectronic devices, because of their enabling properties. Recently, Mn2+ doping directly into APbCl3-type three-dimensional (3D) nanocrystals, manifesting host-to-dopant energy transfer, have been reported for LED display applications. Strongly bound excitons in the doped system can enhance the dopant-carrier exchange interactions, leading to efficient energy transfer. Here, we report the simple and scalable synthesis of Mn2+-doped (C4H9NH3)2PbBr4 two-dimensional (2D) layered perovskites. The Mn2+-doped 2D perovskite shows enhanced energy transfer efficiency from the strongly bound excitons of the host material to the d electrons of Mn2+ ions, resulting in intense orange-yellow emission, which is due to spin-forbidden internal transition (4T1 → 6A1) with the highest quantum yield (Mn2+) of 37%. Because of this high quantum yield, stability in ambient atmosphere, and simplicity and scalability of the synthetic procedure, Mn2+-doped 2D perovskites could be beneficial as color-converting phosphor material and as energy down-shift coating for perovskite solar cells. The newly developed Mn2+-doped 2D perovskites can be a suitable material to tune dopant-exciton exchange interactions to further explore their magneto-optoelectronic properties.
- Biswas, Anupam,Bakthavatsalam, Rangarajan,Kundu, Janardan
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- Improved recognition of alkylammonium salts by ion pair recognition based on a novel heteroditopic pillar[5]arene receptor
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A novel pillar[5]arene-based heteroditopic receptor for ion pair recognition of alkylammonium salts with different alkyl chain lengths and different counterions was prepared, which showed the best association constant enhancement (71 times) to n-BuNH3+Cl- compared with monotopic receptor 1,4-dimethoxypillar[5]arene over corresponding Br - and CF3COO- salts in chloroform.
- Ni, Mengfei,Guan, Yangfan,Wu, Lin,Deng, Chao,Hu, Xiaoyu,Jiang, Juli,Lin, Chen,Wang, Leyong
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- A Ternary Solvent Method for Large-Sized Two-Dimensional Perovskites
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Recent reports demonstrate that a two-dimensional (2D) structural characteristic can endow perovskites with both remarkable photoelectric conversion efficiency and high stability, but the synthesis of ultrathin 2D perovskites with large sizes by facile solution methods is still a challenge. Reported herein is the controlled growth of 2D (C4H9NH3)2PbBr4perovskites by a chlorobenzene-dimethylformide-acetonitrile ternary solvent method. The critical factors, including solvent volume ratio, crystallization temperature, and solvent polarity on the growth dynamics were systematically studied. Under optimum reaction condition, 2D (C4H9NH3)2PbBr4perovskites, with the largest lateral dimension of up to 40 μm and smallest thickness down to a few nanometers, were fabricated. Furthermore, various iodine doped 2D (C4H9NH3)2PbBrxI4?xperovskites were accessed to tune the optical properties rationally.
- Chen, Junnian,Gan, Lin,Zhuge, Fuwei,Li, Huiqiao,Song, Jizhong,Zeng, Haibo,Zhai, Tianyou
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- In Situ Epitaxial Growth of Centimeter-Sized Lead-Free (BA)2CsAgBiBr7/Cs2AgBiBr6Heterocrystals for Self-Driven X-ray Detection
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Halide perovskite heterocrystals, composed of distinct perovskite single crystals, have generated great interest for both fundamental research and applied device designs. One of the key advantages of using such a heterocrystal is its built-in electric potential, which enhances charge transport and suppresses the noise in the solid-state devices. On the basis of this strategy, high-performance optoelectronic devices (e.g., X-ray detectors) have been successfully demonstrated. However, the toxicity of metal cations (Pb) in those reported heterocrystals hinders their wider applications. Thus, developing lead-free halide perovskite heterocrystals is significant but remains highly challenging. Here, we report a solution-processed in situ heteroepitaxial approach that enables us to create the first lead-free halide perovskite heterocrystal, (BA)2CsAgBiBr7/Cs2AgBiBr6(BA = n-butylammonium), with dimensions of up to 10 × 7 × 6 mm3. The as-grown heterocrystals have high crystalline quality and present near atomically sharp interfaces. More excitingly, the (BA)2CsAgBiBr7/Cs2AgBiBr6 heterogeneous integration allows the formation of a built-in electric potential in the junction, which triggers spontaneous charge separation/transport. Consequently, X-ray detectors using the heterocrystals can operate in a self-driven mode and exhibit an impressive sensitivity (206 μC Gy-1 cm-2) superior to that of the pristine Cs2AgBiBr6 crystal detectors, an ultralow dark current, and operational stability. Our findings provide the first demonstration of lead-free halide perovskite heterocrystals and may open up opportunities for a host of sustainable and miniaturized perovskite optoelectronic devices.
- Ji, Chengmin,Luo, Junhua,Yao, Yunpeng,Zhang, Xinyuan,Zhu, Tingting
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supporting information
p. 20802 - 20810
(2021/12/14)
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- A new organic-inorganic bismuth halide crystal structure and quantum dot bearing long-chain alkylammonium cations
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It is report here a new family of organic-inorganic bismuth halides bearing a formula of A2BiX5, in which A is monovalent long-chain alkylammonium and X is halide. Two compounds, (BA)2BiBr5 (BA: C4H9NH3 +) and (OA)2BiBr5 (OA: C8H17NH3 +), have been synthesized and investigated by single crystal and powder X-ray diffractions, UV–vis absorption and fluorescence spectroscopies, and density functional theoretical calculations. An orthorhombic crystalline structure with a P212121 space group, which had not been reported for organobismuth halides before, was found existing in (OA)2BiBr5 single crystals. Besides bulk materials, the quantum dots (QDs) of (BA)2BiBr5 and (OA)2BiBr5 were prepared and demonstrated as blue emitters with photoluminescent quantum yields of 1.26% and 0.50%, respectively, after capping with oleic acid. Finally, mixed halides with various I/Br ratios were prepared and found to form certain solid solutions with homogeneous distributed I? and Br?. Upon tuning I/Br ratio, the absorption and emission bands of their QDs can be easily modulated.
- Wang, Jiandong,Li, Jia,Wang, Yong,Xiao, Wen-Jing,Yao, Xiang,Xu, Zi-Wen,Yao, Jianhua,Lin, Jian,Li, Wei-Shi
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p. 155 - 161
(2019/04/26)
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- HIGHLY TUNABLE COLLOIDAL PEROVSKITE NANOPLATELETS
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Colloidal perovskite nanoplatelets can provide a material platform, with tunability extending from the deep UV, across the visible, into the near-IR. The high degree of spectral tunability can be achieved through variation of the cation, metal, and halide composition as well as nanoplatelet thickness.
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Paragraph 0074; 0075; 0076
(2017/11/29)
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- 4-Hydroxyphenacyl Ammonium Salts: A Photoremovable Protecting Group for Amines in Aqueous Solutions
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Irradiation of N-protected p-hydroxyphenacyl (pHP) ammonium caged derivatives at 313 nm releases primary and secondary amines or ammonia in nearly quantitative yields via the photo-Favorskii reaction when conducted in acidic or neutral aqueous buffered media. The reaction efficiencies are strongly dependent on the pH with the most efficient and highest yields obtained when the pH of the media maintains the ammonium and p-hydroxyl groups as their conjugate acids. For example, the overall quantum yields of simple secondary amines release are 0.5 at acidic pH from 3.9 to 6.6 dropping to 0.1 at neutral pH 7.0 and 0.01 at pH 8.4. Speciation studies provide an acid-base profile that helps define the scope and limitations of the reaction. When the pKa of the ammonium group is lower than that of the phenolic hydroxyl group, as is the case for the α-amino-protected amino acids, the more acidic ammonium ion deprotonates as the media pH is changed from acidic toward neutral or basic, thus diminishing the leaving group ability of the amino group. This, in turn, lowers the propensity for the photo-Favorskii rearrangement reaction to occur and opens the reaction pathway to alternative competing photoreduction process.
- Bownik, Iwona,?ebej, Peter,Literák, Jaromír,Heger, Dominik,?imek, Zdeněk,Givens, Richard S.,Klán, Petr
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p. 9713 - 9721
(2015/10/12)
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- JOINT EFFECT OF STRUCTURAL FACTORS, TEMPERATURE, AND POLARITY OF THE MEDIUM ON RATE OF REACTIONS OF BENZYL BROMIDES WITH BUTYLAMINE. MANY-PARAMETER CORRELATIONS
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The rates of the reactions of benzyl bromides with butylamine were measured in nitrobenzene, chlorobenzene, and their mixtures at 40, 50, and 60 deg C and also in a 1:1 mixture of chlorobenzene with cyclohexane at 40 deg C.The effects of the variable factors (the structure of benzyl bromides, temperature, polarity of the medium) on the process rate were evaluated separately and in pairs and the joint effect of all three factors was also determined.The effect of the structure of the substrate and the polarity of the medium on the nature of the transition states in the reactions is discussed.
- Shpan'ko, I. V.,Serebryakov, I. M.,Korostylev, A. P.
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p. 1224 - 1230
(2007/10/02)
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- EFFECT OF THE STRUCTURE OF AMINES ON RATE AND MECHANISM OF THEIR REACTIONS WITH 2-(β,β-DIBROMOVINYL)-5-NITROFURAN IN ACETONITRILE
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The kinetics of the reaction of 2-(β,β-dibromovinyl)-5-nitrofuran with alkylamines of various types (primary, secondary, and tertiary) in acetonitrile at 55 deg C were studied.It was shown that enamines are formed quantitatively in the case of the reactions with secondary amines.At the same time the products from the reactions with primary amines are the corresponding amidines.Here the monosubstitution product is formed at the first stage, as in the case of the reactions with secondary amines, and rearranges to the imidoyl halide with subsequent substitution of the halogen atom at the imidoyl carbon atom.A quantitative assessment is made of the effect of the structure of the enamine on the rate of the processes.
- Kravchenko, V. V.,Kotenko, A. A.,Popov, A. F.,Kostenko, L. I.,Vegh, D.,Kovac, J.
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p. 2140 - 2143
(2007/10/02)
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- KINETICS AND MECHANISM OF REACTION OF AMINES WITH β-BROMOPROPIOPHENONE
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The reaction of β-bromopropiophenone with different amines in acetonitrile at 25 deg C was studied.It was found that in the case of primary and secondary amines, the end products of the reaction are β-aminopropiophenones, which form via the intermediate phenyl vinyl ketone.In the case of tertiary amines, the reaction ends at the stage of the formation of phenyl vinyl ketone.The reactivity of the amines in the formation of phenyl vinyl ketone is preferentially determined by their basicity.
- Popov, A. F.,Piskunova, Z.,Matvienko, V. N.
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p. 1299 - 1302
(2007/10/02)
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- OXALSAEUREDERIVATE DURCH OXIDATIVE KUPPLUNG VON KOHLENMONOXID AN NICKEL
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Carbon monoxide is oxidatively coupled by ligand nickel(II) compounds with secondary, primary amines and with alkali alkoxides to give oxalic acid derivatives.In the case of secondary amines the CO coupling can be run catalytically by adding oxidants like copper(II) salts.The yield of oxalic esters depends on the types of ligands and anions.
- Hoberg, Heinz,Fananas, F. Javier,Riegel, Hans Josef
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p. 267 - 272
(2007/10/02)
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- KINETICS OF THE REACTIONS OF 2-HALOGENOPYRIDINIUM SALTS WITH PRIMARY AND SECONDARY AMINES IN ACETONITRILE
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The kinetics of the reactions of 2-halogeno-N-alkylpyridinium salts with primary and secondary aliphatic amines in acetonitrile at 25 deg C were investigated.The reactions obey second-order relationships.In the reaction of 2-bromo-N-ethylpyridinium bromide with aliphatic amines the effect of electronic and steric factors on the reactivity of the amines was examined.
- Litvinenko, L. M.,Titskii, G. D.,Mitchenko, E. S.
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p. 1731 - 1736
(2007/10/02)
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