| 1. |
- Xu, Weidong, 1988-, et al.
(författare)
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Rational molecular passivation for high-performance perovskite light-emitting diodes
- 2019
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Ingår i: Nature Photonics. - : Springer Nature Publishing AG. - 1749-4885 .- 1749-4893. ; 13:6, s. 418-424
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Tidskriftsartikel (refereegranskat)abstract
- A major efficiency limit for solution-processed perovskite optoelectronic devices, for example light-emitting diodes, is trap-mediated non-radiative losses. Defect passivation using organic molecules has been identified as an attractive approach to tackle this issue. However, implementation of this approach has been hindered by a lack of deep understanding of how the molecular structures influence the effectiveness of passivation. We show that the so far largely ignored hydrogen bonds play a critical role in affecting the passivation. By weakening the hydrogen bonding between the passivating functional moieties and the organic cation featuring in the perovskite, we significantly enhance the interaction with defect sites and minimize non-radiative recombination losses. Consequently, we achieve exceptionally high-performance near-infrared perovskite light-emitting diodes with a record external quantum efficiency of 21.6%. In addition, our passivated perovskite light-emitting diodes maintain a high external quantum efficiency of 20.1% and a wall-plug efficiency of 11.0% at a high current density of 200 mA cm−2, making them more attractive than the most efficient organic and quantum-dot light-emitting diodes at high excitations.
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| 2. |
- Zhang, Tiankai, et al.
(författare)
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Ion-modulated radical doping of spiro-OMeTAD for more efficient and stable perovskite solar cells
- 2022
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Ingår i: Science. - : AMER ASSOC ADVANCEMENT SCIENCE. - 0036-8075 .- 1095-9203. ; 377:6605, s. 495-501
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Tidskriftsartikel (refereegranskat)abstract
- Record power conversion efficiencies (PCEs) of perovskite solar cells (PSCs) have been obtained with the organic hole transporter 2,2,7,7-tetrakis(N,N-di-p-methoxyphenyl-amine)9,9-spirobifluorene (spiro-OMeTAD). Conventional doping of spiro-OMeTAD with hygroscopic lithium salts and volatile 4-tert-butylpyridine is a time-consuming process and also leads to poor device stability. We developed a new doping strategy for spiro-OMeTAD that avoids post-oxidation by using stable organic radicals as the dopant and ionic salts as the doping modulator (referred to as ion-modulated radical doping). We achieved PCEs of >25% and much-improved device stability under harsh conditions. The radicals provide hole polarons that instantly increase the conductivity and work function (WF), and ionic salts further modulate the WF by affecting the energetics of the hole polarons. This organic semiconductor doping strategy, which decouples conductivity and WF tunability, could inspire further optimization in other optoelectronic devices.
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| 3. |
- Gong, Zheng, et al.
(författare)
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A targetable fluorescent probe for detecting mitochondrial viscosity in live cells by using fluorescence lifetime imaging
- 2024
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Ingår i: New Journal of Chemistry. - : ROYAL SOC CHEMISTRY. - 1144-0546 .- 1369-9261.
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Tidskriftsartikel (refereegranskat)abstract
- Intracellular viscosity plays an important role in regulating cellular morphology and physiology and is closely related to a host of diseases. Especially, the changes in mitochondrial viscosity will cause some common diseases such as hyperlipidemia, Alzheimer's disease and cancer. In this work, we report the design of a red-emissive molecular rotor for the detection of mitochondrial viscosity in live cells. The probe showed fascinating performance, such as specific targeting to mitochondria, high sensitivity to viscosity, and rapid fluorescence response, especially the dual response mode of fluorescence intensity and fluorescence lifetime. By using this probe, we realized monitoring of the mitochondrial viscosity variations in live cells under different physiological processes. Our study offers an opportunity to discover potential tools for mitochondria-related physiology and pathology investigation. A D-pi-A typed fluorescence lifetime probe for sensitively detecting viscosity has been designed and synthesized. BSOH has been successfully applied to real-time monitoring mitochondrial viscosity in live cells by fluorescence lifetime imaging.
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| 4. |
- Huang, Shoushuang, et al.
(författare)
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ZIF-assisted construction of magnetic multiple core-shell Fe3O4@ZnO@N-doped carbon composites for effective photocatalysis
- 2019
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Ingår i: Chemical Engineering Science. - : PERGAMON-ELSEVIER SCIENCE LTD. - 0009-2509 .- 1873-4405. ; 209
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Tidskriftsartikel (refereegranskat)abstract
- Magnetic Fe3O4@ZnO@nitrogen-doped carbon (Fe3O4@ZnO@N-C) composites with multiple core-shell structures have been successfully synthesized by calcination of ZIF-8 coated Fe3O4@ZnO core-shell nanocrystals. The morphologies and microstructural characteristics are investigated by X-ray diffraction, Fourier-transform infrared spectrometer, transmission electron microscopy, X-ray photoelectron spectroscopy, physical adsorption of nitrogen, and UV-vis diffuse reflectance spectroscopy. The photocatalytic performances are tested by degrading methylene blue (MB) in aqueous solutions under the irradiation of imitative sunlight. The photocatalytic trials indicate that the Fe3O4@ZnO@N-C composites exhibit improved degradation efficiency compared to the Fe3O4@ZnO precursor. The photocatalytic efficiencies of the as-prepared Fe3O4@ZnO@N-C composites towards MB are 93% under irradiation of imitative sunlight for 90 min and still maintained to be 87% after 6 recycles, which shows very good stability and recyclability. Nitrogen-doped carbon is believed to extend the absorption spectra to the visible-light region. The photodegradation kinetics via using the as-prepared Fe3O4@ZnO@N-C composite as a novel photocatalyst are systematically investigated. (C) 2019 Elsevier Ltd. All rights reserved.
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| 5. |
- Kuang, Chaoyang, et al.
(författare)
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Critical role of additive-induced molecular interaction on the operational stability of perovskite light-emitting diodes
- 2021
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Ingår i: Joule. - : Cell Press. - 2542-4351. ; 5:3, s. 618-630
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Tidskriftsartikel (refereegranskat)abstract
- Despite rapid improvements in efficiency and brightness of perovskite light-emitting diodes (PeLEDs), the poor operational stability remains a critical challenge hindering their practical applications. Here, we demonstrate greatly improved operational stability of high-efficiency PeLEDs, enabled by incorporating dicarboxylic acids into the precursor for perovskite depositions. We reveal that the dicarboxylic acids efficiently eliminate reactive organic ingredients in perovskite emissive layers through an in situ amidation process, which is catalyzed by the alkaline zinc oxide substrate. The formed stable amides prohibit detrimental reactions between the perovskites and the charge injection layer underneath, stabilizing the perovskites and the interfacial contacts and ensuring the excellent operational stability of the resulting PeLEDs. Through rationally optimizing the amidation reaction in the perovskite emissive layers, we achieve efficient PeLEDs with a peak external quantum efficiency of 18.6% and a long half-life time of 682 h at 20 mA cm(-2), presenting an important breakthrough in PeLEDs.
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| 6. |
- Le, Thanh-Tung, et al.
(författare)
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Carbon-Decorated Fe3S4-Fe7Se8 Hetero-Nanowires: Interfacial Engineering for Bifunctional Electrocatalysis Toward Hydrogen and Oxygen Evolution Reactions
- 2020
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Ingår i: Journal of the Electrochemical Society. - : ELECTROCHEMICAL SOC INC. - 0013-4651 .- 1945-7111. ; 167:8
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Tidskriftsartikel (refereegranskat)abstract
- The design and synthesis of complex multi-component heterostructures is an effective strategy to fabricate cost-efficient catalysts for electrochemical water splitting. Herein, one-dimensional porous Fe3S4-Fe7Se8 heterostructured nanowires confined in carbon (Fe3S4-Fe7Se8@C) were synthesized via the selenization of Fe-based organic-inorganic nanowires. Benefiting from the merits of morphology, composition and surface structure characteristics, i.e., the high structural void porosity, the direct electrical pathways of nanowire topology and the conductive carbon layer coating, the titled catalyst not only offered a larger accessible electrocatalytic interface but also facilitated diffusion of the electrolyte and gas. Moreover, the electron redistribution at the Fe3S4-Fe7Se8 heterojunction interfaces reduced the adsorption free-energy barriers on the active sites, endowing the catalysts with faster reaction kinetics and improved electrocatalytic activity. Accordingly, the optimal Fe3S4-Fe7Se8@C produced a low hydrogen evolution reaction overpotential of 124 mV at 10 mA cm (-2) with a Tafel slope of 111.2 mV dec(-1), and an ultralow oxygen evolution reactions overpotential of 219 mV at 20 mA cm (-2 ), respectively. When applied as both anode and cathode for overall water splitting, a low battery voltage of 1.67 V was achieved along with excellent stability for at least 12 h. The work presented here offered a feasible scheme to fabricate non-noble metal-based electrocatalysts for water splitting. (C) 2020 The Author(s). Published on behalf of The Electrochemical Society by IOP Publishing Limited.
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| 7. |
- Qing, Jian, et al.
(författare)
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High-Quality Ruddlesden-Popper Perovskite Films Based on In Situ Formed Organic Spacer Cations
- 2019
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Ingår i: Advanced Materials. - : WILEY-V C H VERLAG GMBH. - 0935-9648 .- 1521-4095. ; 31:41
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Tidskriftsartikel (refereegranskat)abstract
- Ruddlesden-Popper perovskites (RPPs), consisting of alternating organic spacer layers and inorganic layers, have emerged as a promising alternative to 3D perovskites for both photovoltaic and light-emitting applications. The organic spacer layers provide a wide range of new possibilities to tune the properties and even provide new functionalities for RPPs. However, the preparation of state-of-the-art RPPs requires organic ammonium halides as the starting materials, which need to be ex situ synthesized. A novel approach to prepare high-quality RPP films through in situ formation of organic spacer cations from amines is presented. Compared with control devices fabricated from organic ammonium halides, this new approach results in similar (and even better) device performance for both solar cells and light-emitting diodes. High-quality RPP films are fabricated based on different types of amines, demonstrating the universality of the approach. This approach not only represents a new pathway to fabricate efficient devices based on RPPs, but also provides an effective method to screen new organic spacers with further improved performance.
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| 8. |
- Wang, Shangdai, et al.
(författare)
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Multi-functional NiS2/FeS2/N-doped carbon nanorods derived from metal-organic frameworks with fast reaction kinetics for high performance overall water splitting and lithium-ion batteries
- 2019
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Ingår i: Journal of Power Sources. - : ELSEVIER. - 0378-7753 .- 1873-2755. ; 436
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Tidskriftsartikel (refereegranskat)abstract
- The development of cost-effective, highly efficient and robust multi-functional electrode materials can dramatically reduce the overall cost of electrochemical devices. We here report the controlled synthesis of NiS2/FeS2 nanoparticles encapsulated in N-doped carbon nanorods (NiS2/FeS2/NC) through carbonization and sulfurization of Fe/Ni-based bimetallic metal-organic frameworks. Benefiting from both structural and compositional characteristics, the resulting NiS2/FeS2/NC nanorods possess abundant active sites, high electrical conductivity and rapid mass transfer, thereby delivering 10 and 20 mA cm(-2) at overpotential of 172 mV and 231 mV towards the hydrogen evolution reaction and oxygen evolution reaction with robust stability in 1.0 M KOH solution, respectively. When employed as a bifunctional electrocatalyst for overall water splitting, it requires only 1.58 V to deliver a current density of 10 mA cm(-2) in 1.0 M KOH, outperforming that of the commercial Pt/C parallel to RuO2. Additionally, lithium-ion batteries tests also show high reversible capacity (718 mA h g(-1) at 100 mA g(-1)) and excellent cycling stability and rate performance. The work in this paper not only provides a promising strategy for designing efficient multi-functional electrode materials with similar morphology and structure, but also can be extended to the synthesis of other mixed metal sulfides for energy conversion and storage.
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| 9. |
- Xu, Yan, et al.
(författare)
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Impact of Amine Additives on Perovskite Precursor Aging : A Case Study of Light-Emitting Diodes
- 2021
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Ingår i: The Journal of Physical Chemistry Letters. - : American Chemical Society (ACS). - 1948-7185. ; 12:25, s. 5836-5843
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Tidskriftsartikel (refereegranskat)abstract
- Amines are widely employed as additives for improving the performance of metal halide perovskite optoelectronic devices. However, amines are well-known for their high chemical reactivity, the impact of which has yet to receive enough attention from the perovskite light-emitting diode community. Here, by investigating an unusual positive aging effect of CH3NH3I/CsI/PbI2 precursor solutions as an example, we reveal that amines gradually undergo N-formylation in perovskite precursors over time. This reaction is initialized by hydrolysis of dimethylformamide in the acidic chemical environment. Further investigations suggest that the reaction products collectively impact perovskite crystallization and eventually lead to significantly enhanced external quantum efficiency values, increasing from similar to 2% for fresh solutions to greater than or similar to 12% for aged ones. While this case study provides a positive aging effect, a negative aging effect is possible in other perovksite systems. Our findings pave the way for more reliable and reproducible device fabrication and call for further attention to underlying chemical reactions within the perovskite inks once amine additives are included.
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| 10. |
- Zhang, Jibin, et al.
(författare)
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Ligand-Induced Cation-p Interactions Enable High-Efficiency, Bright, and Spectrally Stable Rec. 2020 Pure-Red Perovskite Light-Emitting Diodes
- 2023
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Ingår i: Advanced Materials. - : WILEY-V C H VERLAG GMBH. - 0935-9648 .- 1521-4095.
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Tidskriftsartikel (refereegranskat)abstract
- Achieving high-performance perovskite light-emitting diodes (PeLEDs) with pure-red electroluminescence for practical applications remains a critical challenge because of the problematic luminescence property and spectral instability of existing emitters. Herein, high-efficiency Rec. 2020 pure-red PeLEDs, simultaneously exhibiting exceptional brightness and spectral stability, based on CsPb(Br/I)(3) perovskite nanocrystals (NCs) capping with aromatic amino acid ligands featuring cation-pi interactions, are reported. It is proven that strong cation-pi interactions between the PbI6-octahedra of perovskite units and the electron-rich indole ring of tryptophan (TRP) molecules not only chemically polish the imperfect surface sites, but also markedly increase the binding affinity of the ligand molecules, leading to high photoluminescence quantum yields and greatly enhanced spectral stability of the CsPb(Br/I)(3) NCs. Moreover, the incorporation of small-size aromatic TRP ligands ensures superior charge-transport properties of the assembled emissive layers. The resultant devices emitting at around 635 nm demonstrate a champion external quantum efficiency of 22.8%, a max luminance of 12 910 cd m(-2), and outstanding spectral stability, representing one of the best-performing Rec. 2020 pure-red PeLEDs achieved so far.
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