36945-08-1Relevant articles and documents
Synthesis of Two-Dimensional Perovskite by Inverse Temperature Crystallization and Studies of Exciton States by Two-Photon Excitation Spectroscopy
Chen, Zhihui,Zhang, Qi,Zhu, Menglong,Wang, Xinyun,Wang, Qixing,Wee, Andrew Thye Shen,Loh, Kian Ping,Eda, Goki,Xu, Qing-Hua
, (2020/06/08)
Two-dimensional (2D) organic–inorganic hybrid perovskites (OIHPs), a natural multiple-quantum-well structure with quasi-2D electronic properties, have recently emerged as a promising class of semiconducting materials for photovoltaic and optoelectronic ap
A new organic-inorganic bismuth halide crystal structure and quantum dot bearing long-chain alkylammonium cations
Wang, Jiandong,Li, Jia,Wang, Yong,Xiao, Wen-Jing,Yao, Xiang,Xu, Zi-Wen,Yao, Jianhua,Lin, Jian,Li, Wei-Shi
, p. 155 - 161 (2019/04/26)
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.
Excitonic Properties of Chemically Synthesized 2D Organic–Inorganic Hybrid Perovskite Nanosheets
Zhang, Qi,Chu, Leiqiang,Zhou, Feng,Ji, Wei,Eda, Goki
, (2018/03/29)
2D organic–inorganic hybrid perovskites (OIHPs) represent a unique class of materials with a natural quantum-well structure and quasi-2D electronic properties. Here, a versatile direct solution-based synthesis of mono- and few-layer OIHP nanosheets and a systematic study of their electronic structure as a function of the number of monolayers by photoluminescence and absorption spectroscopy are reported. The monolayers of various OIHPs are found to exhibit high electronic quality as evidenced by high quantum yield and negligible Stokes shift. It is shown that the ground exciton peak blueshifts by ≈40 meV when the layer thickness reduces from bulk to monolayer. It is also shown that the exciton binding energy remains effectively unchanged for (C6H5(CH2)2NH3)2PbI4 with the number of layers. Similar trends are observed for (C4H9NH3)2PbI4 in contrast to the previous report. Further, the photoluminescence lifetime is found to decrease with the number of monolayers, indicating the dominant role of surface trap states in nonradiative recombination of the electron–hole pairs.
Observation of internal photoinduced electron and hole separation in hybrid two-dimentional perovskite films
Liu, Junxue,Leng, Jing,Wu, Kaifeng,Zhang, Jun,Jin, Shengye
supporting information, p. 1432 - 1435 (2017/02/10)
Two-dimensional (2D) organolead halide perovskites are promising for various optoelectronic applications. Here we report a unique spontaneous charge (electron/hole) separation property in multilayered (BA)2(MA)n-1PbnI3n+1 (BA = CH3(CH2)3NH3+, MA = CH3NH3+) 2D perovskite films by studying the charge carrier dynamics using ultrafast transient absorption and photoluminescence spectroscopy. Surprisingly, the 2D perovskite films, although nominally prepared as n = 4 , are found to be mixture of multiple perovskite phases, with n = 2, 3, 4 and ≈ ∞, that naturally align in the order of n along the direction perpendicular to the substrate. Driven by the band alignment between 2D perovskites phases, we observe consecutive photoinduced electron transfer from small-n to large-n phases and hole transfer in the opposite direction on hundreds of picoseconds inside the 2D film of ～358 nm thickness. This internal charge transfer efficiently separates electrons and holes to the upper and bottom surfaces of the films, which is a unique property beneficial for applications in photovoltaics and other optoelectronics devices.
Convenient synthesis of cyclic carbonates from CO2 and epoxides by simple secondary and primary ammonium iodides as metal-free catalysts under mild conditions and its application to synthesis of polymer bearing cyclic carbonate moiety
Aoyagi, Naoto,Furusho, Yoshio,Endo, Takeshi
, p. 1230 - 1242 (2013/03/29)
Hydroiodides of secondary and primary amines effectively catalyzed the reaction of carbon dioxide and epoxides under mild conditions such as ordinary pressure and ambient temperature, to obtain the corresponding five-membered cyclic carbonates in moderate to high yields. Detailed investigation showed that the catalytic activity was highly affected by the counter anions of the ammonium salts; the iodides catalyzed efficiently the carbonate-forming reactions, whereas the bromide and chloride counterparts exhibited almost no catalysis. We also revealed that two important factors on the amine moieties that affected the catalytic reactions. First, the catalytic activity increased with increasing bulkiness of the substituents on the ammonium nitrogen atoms. Second, the catalysis became more efficient as the parent amines become more basic. Dicyclohexylammonium iodide was the best catalyst among the ammonium salts investigated in this study. As an application of this reaction system, we synthesized homo- and copolymers bearing epoxide pendant groups as substrates, which were converted with high efficiency into the corresponding homo- and copolymers bearing cyclic carbonate pendant groups under 1 atm at 45 °C. All polymers were easily purified simply by precipitation in water, and were isolated in high yields (>95%). 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013. Copyright
