13 results on '"Wang, Ti"'
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2. Inorganic A-site cations improve the performance of band-edge carriers in lead halide perovskites
- Author
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Wang, Cheng, Rong, Yaoguang, and Wang, Ti
- Published
- 2023
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3. Excessive Iodine Enabled Ultrathin Inorganic Perovskite Growth at the Liquid‐Air Interface.
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Yuan, Jiaxiao, Zhang, Xiaomin, Zhou, Dawei, Ge, Feixiang, Zhong, Jingxian, Zhao, Sihan, Ou, Zhenwei, Zhan, Guixiang, Zhang, Xu, Li, Congzhou, Tang, Jin, Bai, Qi, Zhang, Junran, Zhu, Chao, Wang, Ti, Ruan, Longfei, Zhu, Chongqin, Song, Xuefen, Huang, Wei, and Wang, Lin
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IODINE ,PEROVSKITE ,INORGANIC synthesis ,OPTICAL properties ,HETEROSTRUCTURES ,NANOSTRUCTURED materials - Abstract
The liquid‐air interface offers a platform for the in‐plane growth of free‐standing materials. However, it is rarely used for inorganic perovskites and ultrathin non‐layered perovskites. Herein the liquid‐air interfacial synthesis of inorganic perovskite nanosheets (Cs3Bi2I9, Cs3Sb2I9) is achieved simply by drop‐casting the precursor solution with only the addition of iodine. The products are inaccessible without iodine addition. The thickness and lateral size of these nanosheets can be adjusted through the iodine concentration. The high volatility of the iodine spontaneously drives precursors that normally stay in the liquid to the liquid‐air interface. The iodine also repairs in situ iodine vacancies during perovskite growth, giving enhanced optical and optoelectronic properties. The liquid‐air interfacial growth of ultrathin perovskites provides multi‐degree‐of‐freedom for constructing perovskite‐based heterostructures and devices at atomic scale. [ABSTRACT FROM AUTHOR]
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- 2023
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4. Synergistic passivation and stepped-dimensional perovskite analogs enable high-efficiency near-infrared light-emitting diodes.
- Author
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Liu, Yongjie, Tao, Chen, Cao, Yu, Chen, Liangyan, Wang, Shuxin, Li, Pei, Wang, Cheng, Liu, Chenwei, Ye, Feihong, Hu, Shengyong, Xiao, Meng, Gao, Zheng, Gui, Pengbing, Yao, Fang, Dong, Kailian, Li, Jiashuai, Hu, Xuzhi, Cong, Hengjiang, Jia, Shuangfeng, and Wang, Ti
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LIGHT emitting diodes ,PEROVSKITE ,PASSIVATION ,QUANTUM efficiency ,NEAR infrared radiation ,ELECTRON transport - Abstract
Formamidinium lead iodide (FAPbI
3 ) perovskites are promising emitters for near-infrared light-emitting diodes. However, their performance is still limited by defect-assisted nonradiative recombination and band offset-induced carrier aggregation at the interface. Herein, we introduce a couple of cadmium salts with acetate or halide anion into the FAPbI3 perovskite precursors to synergistically passivate the material defects and optimize the device band structure. Particularly, the perovskite analogs, containing zero-dimensional formamidinium cadmium iodide, one-dimensional δ-FAPbI3 , two-dimensional FA2 FAn-1 Pbn I3n+1 , and three-dimensional α-FAPbI3 , can be obtained in one pot and play a pivotal and positive role in energy transfer in the formamidinium iodide-rich lead-based perovskite films. As a result, the near-infrared FAPbI3 -based devices deliver a maximum external quantum efficiency of 24.1% together with substantially improved operational stability. Combining our findings on defect passivation and energy transfer, we also achieve near-infrared light communication with device twins of light emitting and unprecedented self-driven detection. Defect-assisted nonradiative recombination and carrier aggregation at the interface hinder the potential of perovskites as emitter for light-emitting diodes. Here, Fang et al. achieve an external quantum efficiency of 24.1% by combining multidimensional perovskite with cascade conduction bands. [ABSTRACT FROM AUTHOR]- Published
- 2022
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5. Highly Efficient Quasi‐2D Green Perovskite Light‐Emitting Diodes with Bifunctional Amino Acid.
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Liu, Chenwei, Liu, Yongjie, Wang, Shuxin, Liang, Jiwei, Wang, Cheng, Yao, Fang, Ke, Weijun, Lin, Qianqian, Wang, Ti, Tao, Chen, and Fang, Guojia
- Subjects
LIGHT emitting diodes ,QUANTUM confinement effects ,PEROVSKITE ,AMINO acids ,METHYLAMMONIUM ,QUANTUM efficiency ,ENERGY transfer - Abstract
Quasi‐two‐dimensional (quasi‐2D) perovskite light‐emitting diodes (PeLEDs) are considered as one of the most potential candidates in electroluminescence territory owing to their unique quantum confinement effect and excellent thermal stability of the light. Nevertheless, heterogeneous energy domain distribution leads to severe non‐radiative recombination in the process of energy transfer, which enormously hinders the performance and application of PeLEDs. Herein, an ambipolar amino acid, 5‐aminovaleric acid (5AVA), is demonstrated to be able to coordinate lead and halides simultaneously with its carboxyl and amidogen groups. The coordinated ambipolar molecule not only reconstitutes energy domains of perovskites but also minimizes the interfacial defects of PeLEDs. Accordingly, the presence of 5AVA in perovskite precursors leads to dramatic suppression of the n = 1 and n = 2 phases and accelerates energy transfer from wide bandgap domains to narrow bandgap ones. As a result, maximum external quantum efficiency (EQE) of 19.3% (18.20% ± 1.10%) is achieved in quasi‐2D green PeLEDs with current efficiency of 61.7 cd A−1. [ABSTRACT FROM AUTHOR]
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- 2022
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6. Beyond the Phase Segregation: Probing the Irreversible Phase Reconstruction of Mixed‐Halide Perovskites.
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Li, Zhe, Zheng, Xin, Xiao, Xuan, An, Yongkang, Wang, Yanbo, Huang, Qingyi, Li, Xiong, Cheacharoen, Rongrong, An, Qinyou, Rong, Yaoguang, Wang, Ti, and Xu, Hongxing
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PEROVSKITE ,CHARGE injection ,PHASE transitions ,PHOTOLUMINESCENCE ,OPEN-ended questions - Abstract
Mixed‐halide perovskites can undergo a photoinduced phase segregation. Even though many reports have claimed that such a phase segregation process is reversible, what happens after phase segregation and its impact on the performance of perovskite‐based devices are still open questions. Here, the phase transformation of MAPb(I1−xBrx)3 after phase segregation and probe an irreversible phase reconstruction of MAPbBr3 is investigated. The photoluminescence imaging microscopy technique is introduced to in situ record the whole process. It is proposed that the type‐I band alignment of segregated I‐rich and Br‐rich domains can enhance the emission of the I‐rich domains by suppressing the nonradiative recombination channels. At the same time, the charge injection from Br‐rich to I‐rich domains drives the expulsion of iodide from the lattice, and thus triggers the reconstruction of MAPbBr3. The work highlights the significance of ion movements in mixed‐halide perovskites and provides new perspectives to understand the property evolution. [ABSTRACT FROM AUTHOR]
- Published
- 2022
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7. Improved Performance and Stability of Perovskite Solar Modules by Regulating Interfacial Ion Diffusion with Nonionic Cross‐Linked 1D Lead‐Iodide.
- Author
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Zeng, Haipeng, Li, Lin, Liu, Fengxiang, Li, Min, Zhang, Shujing, Zheng, Xin, Luo, Long, You, Shuai, Zhao, Yang, Guo, Rui, Gong, Zhongmiao, Huang, Rong, Li, Zhe, Wang, Ti, Cui, Yi, Rong, Yaoguang, and Li, Xiong
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PEROVSKITE ,DIFFUSION barriers ,LEAD iodide ,LEAD halides ,IONS ,DIPHENYLPHOSPHINE - Abstract
Long‐term stability has become the major obstacle for the successful large‐scale application of perovskites devices. Owing to the ionic nature of metal‐halide perovskites, the interfacial ion diffusion can induce irreversible degradation under operational conditions, which presents a great challenge to realize stable perovskite solar modules. Here, a diphenylphosphine oxide compound, ethane‐1,2‐diylbis(diphenylphosphine oxide) (DPPO) is introduced to coordinate with lead iodide and form a cross‐linked 1D Pb3I6‐DPPO (1D‐PbI2) complex. These judiciously designed cross‐linked nonionic low‐dimensional lead halide/organic adducts can passivate the defects of perovskite while acting as a robust ion diffusion barrier, thus significantly improving the electronic quality and intrinsic stability of perovskite films. As a result, high‐performance inverted (p‐i‐n) solar modules with a champion efficiency approaching 19% (a certified stabilized efficiency of 17.8%) for active device areas above 17 cm2 without the use of antisolvents, accompanied by outstanding operational stability under heat stress and continuous illumination are achieved. [ABSTRACT FROM AUTHOR]
- Published
- 2022
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8. Ultra-bright pure green perovskite light-emitting diodes.
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Zheng, Haihua, Zhou, Zhongpo, Wang, Ti, Gui, Pengbin, Wu, Hao, and Liu, Chang
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STRAY currents ,ELECTRON-hole recombination ,QUANTUM efficiency ,PEROVSKITE ,THERMAL stability ,PHOTOLUMINESCENCE - Abstract
Inorganic perovskites, such as CsPbX
3 (X = Cl, Br, I), have attracted attention due to their excellent thermal stabilities and high photoluminescence quantum efficiencies. Here, we report on all-inorganic light-emitting diodes (LEDs), including inorganic perovskite emitters (CsPbBr3 ) based on the heterostructure of n-ZnO/Al2 O3 /CsPbBr3 /p-GaN. The effects of the CsPbBr3 and Al2 O3 interlayers on the electroluminescence performance have been systematically investigated. It is observed that the Al2 O3 interlayer plays an important role in determining the emission performance. By introducing the Al2 O3 layers, the electron–hole recombination can almost be limited within the perovskite. The emission peaks of the heterojunction LEDs change from blue-green to pure green with the increased luminous intensities and decreased leakage currents. It provides an idea for the preparation of all-inorganic perovskite LEDs. [ABSTRACT FROM AUTHOR]- Published
- 2021
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9. Investigating the iodide and bromide ion exchange in metal halide perovskite single crystals and thin films.
- Author
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Huang, Qingyi, Li, Zhe, Chen, Xiayan, Xia, Yongkang, Zheng, Ziwei, Mei, Anyi, Zhu, Kai, Hu, Yue, Wang, Ti, Rong, Yaoguang, and Han, Hongwei
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METAL halides ,SINGLE crystals ,THIN films ,BROMIDE ions ,ION exchange (Chemistry) ,PEROVSKITE - Abstract
The anion exchange between MAPbX
3 (X = I− or Br− ) and MAX salts in a solution environment is investigated. We find that I− can enter MAPbBr3 single crystals (SC) in millimeter scale, while Br− can only penetrate the surface of MAPbI3 SC in a micrometer scale. Due to the lattice variation, the reaction is partially reversible. [ABSTRACT FROM AUTHOR]- Published
- 2021
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10. Tailoring the Dimensionality of Hybrid Perovskites in Mesoporous Carbon Electrodes for Type‐II Band Alignment and Enhanced Performance of Printable Hole‐Conductor‐Free Perovskite Solar Cells.
- Author
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Chen, Xiayan, Xia, Yongkang, Huang, Qingyi, Li, Zhe, Mei, Anyi, Hu, Yue, Wang, Ti, Cheacharoen, Rongrong, Rong, Yaoguang, and Han, Hongwei
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SOLAR cells ,PEROVSKITE ,MANUFACTURING processes ,OPTOELECTRONICS ,OXIDE minerals - Abstract
Printable hole‐conductor‐free perovskite solar cells (PSCs) have attracted intensive research attention due to their high stability and simple manufacturing process. However, the cells have suffered severe potential loss in the absence of the hole transporting layer. The dimensionality of the perovskite absorber in the mesoporous carbon electrodes by conducting post‐treatments is reduced. The low‐dimensional perovskites possess wide‐bandgaps and form type‐II band alignment, favoring directional charge transportation and thus enhancing the device performance. For the cells using MAPbI3 (MA = methylammonium) as the light absorber, the open‐circuit voltage (VOC) is significantly enhanced from 0.92 to 0.98 V after posttreatment, delivering an overall efficiency of 16.24%. For the cells based on FAPbI3 (FA = formamadinium), a high efficiency of 17.47% is achieved with VOC of 1.02 V, which are both the highest reported values for printable hole‐conductor‐free PSCs. This strategy provides a facile method for tuning the energy level alignment for mesoscopic perovskite‐based optoelectronics. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
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11. Inhibiting Cation Segregation to Enable Highly Efficient Perovskite Light‐Emitting Diodes.
- Author
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Dong, Chaomin, Chen, Guoyi, Yao, Fang, yu, Zhiqiu, Dong, Kailian, Du, Shengjie, Huang, Lishuai, Wang, Cheng, Wang, Ti, Wang, Shuxin, Ke, Weijun, and Fang, Guojia
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HYDROGEN bonding interactions , *CRYSTALLIZATION kinetics , *QUANTUM efficiency , *MOTION picture distribution , *PEROVSKITE - Abstract
Perovskite light‐emitting diodes (PeLEDs) present potential applications for next‐generation displays due to their excellent luminescent properties and solution processing. The formamidinium‐caesium lead bromide (FAxCs1−xPbBr3) mixed cation strategy is one of the primary methods to achieve high‐performance of Cs‐dominate PeLEDs system. However, the inhomogeneous distribution of cations is detrimental to the photoelectronic performance of Cs‐dominated PeLEDs. Here, in mixed FA/Cs perovskite films, it is observed that Cs, Br and trace Pb elements precipitated on the surface of the perovskite films. It is found that the segregation of cations is induced by the uncontrollable crystallization process of Cs/FA cations. By introducing biuret additive, the hydrogen bonding interaction of biuret and FA cation balances crystallization rate, which therefore significantly improves the crystal quality and cations distribution of perovskite films. As a result, green PeLEDs with a high external quantum efficiency of 28.8% are obtained, and represent five times enhancement in half‐life time (
T 50) of 2.48 h at an initial luminance of 100 cd m−2 relative to the control device. The results help to understand the relationship between cationic distribution and PeLEDs properties, offering significant insights for modulating the performance of PeLEDs. [ABSTRACT FROM AUTHOR]- Published
- 2024
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12. A generic lanthanum doping strategy enabling efficient lead halide perovskite luminescence for backlights.
- Author
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Liu, Yongjie, Wang, Cheng, Chen, Guoyi, Wang, Shuxin, Yu, Zhiqiu, Wang, Ti, Ke, Weijun, and Fang, Guojia
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PEROVSKITE , *LANTHANUM , *LEAD halides , *BROMINE , *CESIUM ions , *LIQUID crystal displays , *LUMINESCENCE , *QUANTUM efficiency - Abstract
[Display omitted] Metal halide perovskites films have attracted great interest because of their solution-proceed fabrication and potential applications for next-generation displays. However, their non-ideal photoluminescence quantum efficiency (PLQE) and stability still does not meet the requirements of displays. Here, we adopt lanthanum ion (La3+) doping strategy to enhance its luminescence performance and the possibility of taking it to commercialization. In addition to the entry of lanthanum ions into the lattice to greatly improve the crystal quality, the excess La3+ gives rise to the formation of newly developed formamidinium cesium lanthanum bromine, (FA, Cs) 2 LaBr 5 , which provides additional energy transport pathways, therefore concentrating more energy onto the perovskite host. Consequently, a near-unity PLQE of 99.5% is realized in standardized green-emission cesium (Cs)/formamidinium (FA) mixed FA 0.7 Cs 0.3 PbBr 3 perovskite films. The introduction of La3+ can also lead to markedly stability with nearly 1000 days' shelf storage half-lifetime and 400 hours' light-irradiation T 90 lifetime as well as much-enhanced color purity. Moreover, the films with La3+ doping enable full-visible spectral enhancement and high-performance white light emission and trichromatic luminescence with 98.9% coverage of the color gamut area required for the Rec. 2020 standard, which suggest that perovskite films have great application potential for backlights in liquid crystal display technologies. [ABSTRACT FROM AUTHOR]
- Published
- 2023
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13. Homogenized halides and alkali cation segregation in alloyed organic-inorganic perovskites.
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Correa-Baena, Juan-Pablo, Luo, Yanqi, Brenner, Thomas M., Snaider, Jordan, Sun, Shijing, Li, Xueying, Jensen, Mallory A., Hartono, Noor Titan Putri, Nienhaus, Lea, Wieghold, Sarah, Poindexter, Jeremy R., Wang, Shen, Meng, Ying Shirley, Wang, Ti, Lai, Barry, Holt, Martin V., Cai, Zhonghou, Bawendi, Moungi G., Huang, Libai, and Buonassisi, Tonio
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HALIDES , *CATIONS , *PEROVSKITE , *ALKALI metals , *SOLAR cells , *CESIUM iodide , *CHARGE carriers - Abstract
The role of the alkali metal cations in halide perovskite solar cells is not well understood. Using synchrotron-based nano–x-ray fluorescence and complementary measurements, we found that the halide distribution becomes homogenized upon addition of cesium iodide, either alone or with rubidium iodide, for substoichiometric, stoichiometric, and overstoichiometric preparations, where the lead halide is varied with respect to organic halide precursors. Halide homogenization coincides with long-lived charge carrier decays, spatially homogeneous carrier dynamics (as visualized by ultrafast microscopy), and improved photovoltaic device performance. We found that rubidium and potassium phase-segregate in highly concentrated clusters. Alkali metals are beneficial at low concentrations, where they homogenize the halide distribution, but at higher concentrations, they form recombination-active second-phase clusters. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
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