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Start Over Author "Hong, Maochun" Journal journal of the american chemical society
36 results on '"Hong, Maochun"'

12. Two Non-π-Conjugated Deep-UV Nonlinear Optical Sulfates

Author

Li, Yanqiang, primary, Liang, Fei, additional, Zhao, Sangen, additional, Li, Lina, additional, Wu, Zhenyue, additional, Ding, Qingran, additional, Liu, Shuai, additional, Lin, Zheshuai, additional, Hong, Maochun, additional, and Luo, Junhua, additional

Published
2019
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16. Stabilizing Cesium Lead Halide Perovskite Lattice through Mn(II) Substitution for Air-Stable Light-Emitting Diodes

Author

Zou, Shenghan, Liu, Yongsheng, Li, Jianhai, Liu, Caiping, Feng, Rui, Jiang, Feilong, Li, Yongxiang, Song, Jizhong, Zeng, Haibo, Hong, Maochun, and Chen, Xueyuan

Abstract

All-inorganic cesium lead halide perovskite (CsPbX3, X = Cl, Br, and I) quantum dots (QDs), possessing high photoluminescence quantum yields and tunable color output, have recently been endowed great promise for high-performance solar cells and light-emitting diodes (LEDs). Although moisture stability has been greatly improved through separating QDs with a SiO2shell, the practical applications of CsPbX3QDs are severely restricted by their poor thermal stability, which is associated with the intrinsically low formation energies of perovskite lattices. In this regard, enhancing the formation energies of perovskite lattices of CsPbX3QDs holds great promise in getting to the root of their poor thermal stability, which hitherto remains untouched. Herein, we demonstrate an effective strategy through Mn2+substitution to fundamentally stabilize perovskite lattices of CsPbX3QDs even at high temperatures up to 200 °C under ambient air conditions. We employ first-principle calculations to confirm that the significantly improved thermal stability and optical performance of CsPbX3:Mn2+QDs arise primarily from the enhanced formation energy due to the successful doping of Mn2+in CsPbX3QDs. Benefiting from such an effective substitution strategy, these Mn2+-doped CsPbX3QDs can function well as efficient light emitters toward the fabrication of high-performance perovskite LEDs.

Published
2024
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17. Control the Structure of Zr-Tetracarboxylate Frameworks through Steric Tuning

Author

Pang, Jiandong, Yuan, Shuai, Qin, Junsheng, Liu, Caiping, Lollar, Christina, Wu, Mingyan, Yuan, Daqiang, Zhou, Hong-Cai, and Hong, Maochun

Abstract

Ligands with flexible conformations add to the structural diversity of metal–organic frameworks but, at the same time, pose a challenge to structural design and prediction. Representative examples include Zr-tetracarboxylate-based MOFs, which afford assorted structures for a wide range of applications, but also complicate the structural control. Herein, we systematically studied the formation mechanism of a series of (4,8)-connected Zr-tetracarboxylate-based MOFs by altering the substituents on different positions of the organic linkers. Different ligand rotamers give rise to three types of structures with flu, scu, and csqtopologies. A combination of experiment and molecular simulation indicate that the steric hindrance of the substituents at different positions dictates the resulting MOF structures. Additionally, the controllable formation of different structures was successfully implemented by a combination of linkers with different steric effects at specific positions.

Published
2024
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22. Spacer Cation Alloying of a Homoconformational Carboxylate transIsomer to Boost in-Plane Ferroelectricity in a 2D Hybrid Perovskite

Author

Liu, Yi, Han, Shiguo, Wang, Jiaqi, Ma, Yu, Guo, Wuqian, Huang, Xiao-Ying, Luo, Jun-Hua, Hong, Maochun, and Sun, Zhihua

Abstract

Two-dimensional (2D) hybrid perovskites of Ruddlesden–Popper (RP) lattices are recently booming as a vigorous class of ferroelectrics, whereas their intrinsic van der Waals gaps exert weak interactions that destabilize the layered motifs. Thus, it is an urgent challenge to reduce interlayered energy gaps to allow an exploration of stable RP ferroelectrics. Here, we propose hydrogen bonds to reduce van der Waals gaps of 2D RP-type perovskites while the ferroelectricity is retained. For the first time, a homoconformational transisomer has been alloyed as the spacing cation of the 2D ferroelectric (t-ACH)2(EA)2Pb3Br10(1, where t-ACH is 4-aminomethyl-1-cyclohexanecarboxylate and EA is ethylammonium). Strikingly, the strong O–H···O hydrogen bonds link adjacent spacing sheets to build a quasi-RP motif with a lower energy gap. In terms of ferroelectricity, the mixed-cation alloying has a crucial role in spontaneous polarization (Ps), as verified by structure analyses, quadratic optical nonlinearity, and electric hysteresis loops. The ordering of t-ACH+and EA+cations induces mmmFmsymmetry breaking, along with an unusual in-plane Psvalue of ∼2.9 μC/cm2in the acplane. In combination with the anisotropic nature of its 2D motif, this ferroelectricity creates strong linearly polarized light sensitivity with a large dichroism ratio of ∼3.2, far beyond those of most of the inorganic 2D systems. As far as we know, a 2D RP-type ferroelectric with a transisomer cationic spacer is unprecedented, and the concept of reducing energy gaps via H-bonding interactions will strengthen the layered perovskite structure and shed light on the rational design of stable ferroelectrics toward photoelectric applications.

Published
2021
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24. Trilayered Lead Chloride Perovskite Ferroelectric Affording Self-Powered Visible-Blind Ultraviolet Photodetection with Large Zero-Bias Photocurrent

Author

Wang, Sasa, Li, Lina, Weng, Wen, Ji, Chengmin, Liu, Xitao, Sun, Zhihua, Lin, Wenxiong, Hong, Maochun, and Luo, Junhua

Abstract

Perovskite ferroelectrics, in which the spontaneous polarization (Ps) is conducive to the separation of photoexcited charge carriers, have shown great potential for self-powered photodetection. Nevertheless, such self-powered ferroelectric photodetectors are mostly dominated by traditional inorganic oxides and exhibit relatively small zero-bias photocurrent, which limit their further application. Herein, we present a wide-bandgap 2D trilayered lead chloride hybrid perovskite ferroelectric, EA4Pb3Cl10(1, EA = ethylammonium), which shows a notable Psof ∼4.5 μC/cm2and a high Curie temperature (415 K) beyond that of BaTiO3(393 K). Significantly, benefiting from the wide bandgap of 3.39 eV, a self-powered visible-blind ultraviolet (UV) photodetector has been successfully realized, with a zero-bias photocurrent as high as 18.6 μA/cm2, which is nearly 2 orders of magnitude larger than those of mostly conventional inorganic ferroelectrics. As a pioneering study, this work offers an efficient approach for exploring wide-bandgap perovskite ferroelectrics and will excavate their application in the field of self-powered visible-blind UV photodetection.

Published
2020
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35. Precisely Tailoring a FAPbI 3 -Derived Ferroelectric for Sensitive Self-Driven Broad-Spectrum Polarized Photodetection.

Author

Xu Z, Dong X, Wang L, Wu H, Liu Y, Luo J, Hong M, and Li L

Abstract

Benefiting from superior semiconducting properties and the angle-dependence of the bulk photovoltaic effect (BPVE) on polarized light, the two-dimensional (2D) hybrid perovskite ferroelectrics are developed for sensitive self-powered polarized photodetection. Most of the currently reported ferroelectric-driven polarized photodetection is restricted to the shortwave optical response, and expanding the response range is urgently needed. Here we report the first instance of a FAPbI 3 -derived (2D) perovskite ferroelectric, (BA) 2 (FA)Pb 2 I 7 ( 1 , BA is n -butylammonium, FA is formamidinium). It exhibited a notably high thermostability and broad-spectrum adsorption extending to around 650 nm. Significantly, 1 demonstrated ferroelectricity-driven self-powered polarized photodetection under 637 nm with an anisotropic photocurrent ratio of ∼1.96, ultrahigh detectivity of 3.34 × 10 12 Jones, and long-term repetition. This research will shed light on the development of new ferroelectrics for potential application in broad-spectrum polarization-based optoelectronics.

Published
2023
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36. Non-Centrosymmetric RbNaMgP 2 O 7 with Unprecedented Thermo-Induced Enhancement of Second Harmonic Generation.

Author

Zhao S, Yang X, Yang Y, Kuang X, Lu F, Shan P, Sun Z, Lin Z, Hong M, and Luo J

Abstract

It is of great difficulty to obtain deep-UV transparent materials with enhanced second harmonic generation (SHG), mainly limited by the theoretically poor transparency of these materials in the deep-UV spectral region. Here we report a new noncentrosymmetric, deep-UV transparent phosphate RbNaMgP 2 O 7 , which undergoes a thermo-induced reversible phase transition (at a high temperature of 723 K) and correspondingly an evident SHG enhancement up to ∼1.5 times. The phase transition is aroused by the twist of [P 2 O 7 ] 4- dimers with deviation from the P-O-P equilibrium positions. Theoretical analyses reveal that the enhanced SHG can be ascribed to the thermo-induced collective alignment of SHG-active [P 2 O 7 ] 4- dimers along the polar axis of high-temperature phase. This work provides an unprecedented physical routine (to SHG-enhanced materials) that is distinguished from the traditional one by chemical design and synthesis.

Published
2018
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