| 1. |
- Zhang, Jibin, et al.
(author)
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Highly Luminescent and Stable CsPbI3 Perovskite Nanocrystals with Sodium Dodecyl Sulfate Ligand Passivation for Red-Light-Emitting Diodes
- 2021
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In: The Journal of Physical Chemistry Letters. - : AMER CHEMICAL SOC. - 1948-7185. ; 12:9, s. 2437-2443
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Journal article (peer-reviewed)abstract
- CsPbI3 perovskite nanocrystals (NCs) have recently emerged as promising materials for optoelectronic devices because of their superior properties. However, the poor stability of the CsPbI3 NCs induced by easy ligand desorption represents a key issue limiting their practical applications. Herein, we report stable and highly luminescent black-phase CsPbI3 NCs passivated by novel ligands of sodium dodecyl sulfate (SDS). Theoretical calculation results reveal a stronger adsorption energy of SDS molecules at the CsPbI3 surface than that of commonly used oleic acid. As a result, the defect formation caused by the ligand loss during the purification process is greatly suppressed. The optimized SDS- CsPbI3 NCs exhibit significantly reduced surface defects, much enhanced stability, and superior photoluminescence efficiency. The red perovskite light-emitting diodes based on the SDS-CsPbI3 NCs demonstrate an external quantum efficiency of 8.4%, which shows a 4-fold improvement compared to the devices based on the oleic acid-modified CsPbI3 NCs.
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| 2. |
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| 3. |
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| 4. |
- Su, Wen, et al.
(author)
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Opportunities and challenges of chiral perovskites for spin-LEDs
- 2022
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In: TRENDS IN CHEMISTRY. - : ELSEVIER. - 2589-5974. ; 4:11, s. 965-968
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Journal article (other academic/artistic)abstract
- Chiral perovskites have drawn intensive attention in recent years due to their promising optospintronic applications. In this forum article, the unique properties of chiral perovskites and their applications in circularly polarized light emission (CP-LE) and spin light-emitting di-odes (LEDs) are briefly introduced, along with the challenges and plausible prospects in this field.
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| 5. |
- Su, Wen, et al.
(author)
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Perovskite nanocrystal LEDs: Large areas for efficient vivid displays
- 2022
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In: Matter. - : ELSEVIER. - 2590-2393 .- 2590-2385. ; 5:8, s. 2450-2452
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Journal article (peer-reviewed)abstract
- Large-area perovskite LEDs (PeLEDs) are promising for cost-effective and high-throughput industrial applications. However, growing large-area efficient perovskite light emitters remains a big challenge. In a recent study in Nature Nanotechnology, Lee et al. demonstrated a simple modified bar-coating method for fabricating highly efficient and large-area perovskite nanocrystal-based PeLEDs with external quantum efficiency over 20% for a large pixel area of 900 mm(2).
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| 6. |
- Su, Wen, et al.
(author)
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QD-LEDs: High efficiency and long-term stability toward practical applications
- 2022
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In: Matter. - : ELSEVIER. - 2590-2393 .- 2590-2385. ; 5:8, s. 2464-2466
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Journal article (other academic/artistic)abstract
- Quantum dot LEDs (QD-LEDs) are promising for display and lighting applications. However, fabricating stable, efficient green and blue QD-LEDs remains a big challenge. In a recent study in Nature Photonics, Jin et al. developed a general strategy to eliminate charge leakage for the fabrication of efficient QD-LEDs with exceptional long-term stability (T-95 lifetime of 580,000 h for green and 4,400 h for blue).
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| 7. |
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| 8. |
- Tang, Weidong, et al.
(author)
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The roles of metal oxidation states in perovskite semiconductors
- 2023
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In: Matter. - : CELL PRESS. - 2590-2393 .- 2590-2385. ; 6:11, s. 3782-3802
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Research review (peer-reviewed)abstract
- Metal halide perovskites are an emerging materials platform for optoelectronic, spintronic, and thermoelectric applications. The field of perovskite materials and devices has progressed rapidly over the past decade. For halide perovskite materials, a range of physical and chemical properties such as crystal structure, bandgap, charge carrier density, and stability that govern the device functionalities are critically determined by the oxidation states of the B-site metal ions. However, such an important mechanistic connection unique to halide perovskites is not well established, limiting the pace of development in this area. In this review, we identify the roles of metal oxidation states in perovskite semiconductors. The redox reactions leading to these states, and their effects on the materials properties, are clarified. Finally, we suggest routes to improving device efficiency and stability from the perspective of oxidation state control.
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| 9. |
- Yuan, Fanglong, et al.
(author)
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Bright and stable near-infrared lead-free perovskite light-emitting diodes
- 2024
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In: Nature Photonics. - : NATURE PORTFOLIO. - 1749-4885 .- 1749-4893.
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Journal article (peer-reviewed)abstract
- Long-wavelength near-infrared light-emitting diodes (NIR LEDs) with peak emission wavelengths beyond 900 nm are of critical importance for various applications including night vision, biomedical imaging, sensing and optical communications. However, the low radiance and poor operational stability of state-of-the-art long-wavelength NIR LEDs based on soft materials remain the most critical factors limiting their practical applications. Here we develop NIR LEDs emitting beyond 900 nm with improved performance through the rational manipulation of p doping in all-inorganic tin perovskites (CsSnI3) by retarding and controlling the crystallization process of perovskite precursors in tin-rich conditions. The resulting NIR LEDs exhibit a peak emission wavelength at 948 nm, high radiance of 226 W sr-1 m-2 and long operational half-lifetime of 39.5 h at a high constant current density of 100 mA cm-2. Our demonstration of efficient and stable NIR LEDs operating at high current densities may also open up new opportunities towards electrically pumped lasers. Controlling the intrinsic doping of lead-free perovskites enables near-infrared LEDs emitting at 948 nm with a peak radiance of 226 W sr-1 m-2 and a half-lifetime of 39.5 h.
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| 10. |
- Yuan, Fanglong, et al.
(author)
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Monolayer 2D polymeric fullerene: A new member of the carbon material family
- 2022
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In: Chem. - : CELL PRESS. - 2451-9308 .- 2451-9294. ; 8:8, s. 2079-2081
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Journal article (other academic/artistic)abstract
- Two-dimensional (2D) carbon materials have attracted tremendous attention because of their unique properties, but their structures are currently limited to periodic networks of single carbon atoms. Recently in Nature, Zheng and co-workers demonstrate a new monolayer 2D carbon material composed of interconnected fullerene molecules.
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| 11. |
- Zhang, Jibin, et al.
(author)
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A Multifunctional "Halide-Equivalent" Anion Enabling Efficient CsPb(Br/I)(3) Nanocrystals Pure-Red Light-Emitting Diodes with External Quantum Efficiency Exceeding 23%
- 2023
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In: Advanced Materials. - : WILEY-V C H VERLAG GMBH. - 0935-9648 .- 1521-4095. ; 35:8
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Journal article (peer-reviewed)abstract
- Pure-red perovskite LEDs (PeLEDs) based on CsPb(Br/I)(3) nanocrystals (NCs) usually suffer from a compromise in emission efficiency and spectral stability on account of the surface halide vacancies-induced nonradiative recombination loss, halide phase segregation, and self-doping effect. Herein, a "halide-equivalent" anion of benzenesulfonate (BS-) is introduced into CsPb(Br/I)(3) NCs as multifunctional additive to simultaneously address the above challenging issues. Joint experiment-theory characterizations reveal that the BS- can not only passivate the uncoordinated Pb2+-related defects at the surface of NCs, but also increase the formation energy of halide vacancies. Moreover, because of the strong electron-withdrawing property of sulfonate group, electrons are expected to transfer from the CsPb(Br/I)(3) NC to BS- for reducing the self-doping effect and altering the n-type behavior of CsPb(Br/I)(3) NCs to near ambipolarity. Eventually, synergistic boost in device performance is achieved for pure-red PeLEDs with CIE coordinates of (0.70, 0.30) and a champion external quantum efficiency of 23.5%, which is one of the best value among the ever-reported red PeLEDs approaching to the Rec. 2020 red primary color. Moreover, the BS--modified PeLED exhibits negligible wavelength shift under different operating voltages. This strategy paves an efficient way for improving the efficiency and stability of pure-red PeLEDs.
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| 12. |
- Zhang, Jibin, et al.
(author)
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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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In: Advanced Materials. - : WILEY-V C H VERLAG GMBH. - 0935-9648 .- 1521-4095.
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Journal article (peer-reviewed)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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| 13. |
- Zheng, Xiaopeng, et al.
(author)
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Managing grains and interfaces via ligand anchoring enables 22.3%-efficiency inverted perovskite solar cells
- 2020
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In: NATURE ENERGY. - : Nature Publishing Group. - 2058-7546. ; 5, s. 131-140
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Journal article (peer-reviewed)abstract
- Inverted perovskite solar cells have attracted increasing attention because they have achieved long operating lifetimes. However, they have exhibited significantly inferior power conversion efficiencies compared to regular perovskite solar cells. Here we reduce this efficiency gap using a trace amount of surface-anchoring alkylamine ligands (AALs) with different chain lengths as grain and interface modifiers. We show that long-chain AALs added to the precursor solution suppress nonradiative carrier recombination and improve the optoelectronic properties of mixed-cation mixed-halide perovskite films. The resulting AAL surface-modified films exhibit a prominent (100) orientation and lower trap-state density as well as enhanced carrier mobilities and diffusion lengths. These translate into a certified stabilized power conversion efficiency of 22.3% (23.0% power conversion efficiency for lab-measured champion devices). The devices operate for over 1,000 h at the maximum power point under simulated AM1.5 illumination, without loss of efficiency. While perovskite solar cells with an inverted architecture hold great promise for operation stability, their power conversion efficiency lags behind that of conventional cells. Here, Zheng et al. achieve a certified 22.34% efficiency, exploiting alkylamine ligands as grain and interface modifiers.
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