E02-JEM ARM 300CF
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Xinjuan
Li
,
Zhao
Jiang
,
Si
Chen
,
Yi
Tang
,
Bofeng
Xue
,
Tianhao
Wu
,
Yang
Lu
,
Xavier
Moya
,
Akshay
Rao
,
Zhongzheng
Yu
,
Caterina
Ducati
Diamond Proposal Number(s):
[39081]
Open Access
Abstract: Perovskite quantum dots (PeQDs) offer high photoluminescence quantum efficiencies, precise spectral tunability, and solution-processability, making them promising for advanced optoelectronics. However, their structural and defect evolution under thermal stress remains poorly understood. Here, direct nanoscale insights are provided into temperature-driven phase transition and defect dynamics in CsPbBr3 PeQDs using high-resolution, high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) images, 4D STEM, and photoluminescence spectroscopy. Sub-ångström imaging at room temperature reveals inherent atomic features and octahedral tilting of the lead halide perovskite lattice in PeQDs, suggesting a pre-tilted, low-symmetry state before thermal perturbation. The cryogenic cooling induces a reversible orthorhombic-to-monoclinic phase transition, distinct from bulk perovskite behavior and accompanied by severe strain localization exceeding 20% at surfaces and grain boundaries. A controlled cryogenic post-synthesis treatment can effectively heal defects and improve radiative recombination, whereas prolonged cryo-treatment introduces irreversible structural degradation. These findings highlight the intrinsic structural flexibility of PeQDs and provide a scalable post-synthesis treatment method to optimize the stability and efficiency of QDs for various optoelectronic applications.
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Dec 2025
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I07-Surface & interface diffraction
I15-Extreme Conditions
I19-Small Molecule Single Crystal Diffraction
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Yang
Lu
,
Young-Kwang
Jung
,
Milos
Dubajic
,
Xinjuan
Li
,
Shabnum
Maqbool
,
Qichun
Gu
,
Xinyu
Bai
,
Yorrick
Boeije
,
Xian Wei
Chua
,
Alessandro J.
Mirabelli
,
Taeheon
Kang
,
Lars
Sonneveld
,
Youcheng
Zhang
,
Thomas A.
Selby
,
Capucine
Mamak
,
Kan
Tang
,
Zhongzheng
Yu
,
Tianjun
Liu
,
Miguel
Anaya
,
Stephen
Barlow
,
Seth R.
Marder
,
Bruno
Ehrler
,
Caterina
Ducati
,
Richard H.
Friend
,
Samuel D.
Stranks
Diamond Proposal Number(s):
[32266, 38601, 30043, 33123, 36628, 38508]
Abstract: Halide perovskites exhibit superior optoelectronic properties but lack precise thickness and band offset control in heterojunctions, which is critical for modular multilayer architectures such as multiple quantum wells. We demonstrate vapor-phase, layer-by-layer heteroepitaxial growth exemplified by CsPbBr3 deposition on single crystals of PEA2PbBr4 (PEA: 2-phenylethylammonium). Angstrom-level thickness control and subangstrom smooth layers enable quantum-confined photoluminescence of CsPbBr3 from monolayer, bilayer, and through to bulk. The interfacial structure controls the electronic structure from a Cs‒PEA-terminated interface (type II heterojunction) to a PEA‒PEA-terminated interface (type I heterojunction), with a layer-tunable band offset shift exceeding 0.5 electron volts. Electron transfer from CsPbBr3 to PEA2PbBr4 for a type II Cs‒PEA heterojunction results in delayed electron-hole recombination beyond 10 microseconds. Precise quantum confinement control and large band offset tunability unlock perovskite heterojunctions as platforms for scalable, superlattice-based optoelectronic applications.
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Nov 2025
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I22-Small angle scattering & Diffraction
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Diamond Proposal Number(s):
[33098]
Open Access
Abstract: Particle fusion is key for establishing communication between biological components. For this reason, whole cell fusion plays a crucial role in many processes, including infection, muscle formation and tissue repair. Analogous co-assembly between synthetic nanoparticles represents a similar type of communication mechanism in artificial systems. Other approaches to control such co-assembly rely on incorporating anisotropic recognition units onto particle surfaces to provide a thermodynamic driving force. Here we present a fundamentally different approach, where hetero-fusion between two populations of undecorated polymer nanoparticles is regulated using kinetic control. Fusion extent is tuned simply by adjusting polymer chain length. Fusion is probed using an elemental tagging strategy for cryogenic scanning transmission electron microscopy combined with electron energy loss spectroscopy (cryo-STEM-EELS). Our results demonstrate the emergence of a complex process between populations of synthetic nanoparticles akin to communication. We anticipate such systems-level behaviour that results from hetero-fusion can enable future technologies.
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Nov 2025
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I07-Surface & interface diffraction
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Zhongzheng
Yu
,
Yunzhou
Deng
,
Junzhi
Ye
,
Lars
Van Turnhout
,
Tianjun
Liu
,
Alasdair
Tew
,
Rakesh
Arul
,
Simon
Dowland
,
Yuqi
Sun
,
Xinjuan
Li
,
Linjie
Dai
,
Caterina
Ducati
,
Jeremy J.
Baumberg
,
Richard H.
Friend
,
Robert L. Z.
Hoye
,
Akshay
Rao
Diamond Proposal Number(s):
[32266]
Open Access
Abstract: Insulating nanomaterials have large energy gaps and are only electrically accessible under extreme conditions, such as high-intensity radiation and high temperature, pressure or voltage1,2. Lanthanide-doped insulating nanoparticles (LnNPs) are widely studied owing to their exceptional luminescence properties, including bright, narrow-linewidth, non-blinking and non-bleaching emission in the second near-infrared (NIR-II) range3,4. However, it has not been possible to electrically generate excited states in these insulating nanomaterials under low biases and, therefore, not possible to fabricate optoelectronic devices from these systems. Here we report an electrical excitation pathway to obtain emission from LnNPs. By forming LnNP@organic molecule nanohybrids, in which the recombination of electrically injected charges on the organic molecule is followed by efficient triplet energy transfer (TET) to the LnNP, it is possible to turn on LnNPs under a low operating bias. We demonstrate this excitation pathway in light-emitting diodes (LEDs), with low turn-on voltages of about 5 V, very narrow electroluminescence (EL) spectra and a peak external quantum efficiency (EQE) greater than 0.6% in the NIR-II window5. Our LnNP-based LEDs (LnLEDs) also allow for widely tunable EL properties, by changing the type and concentration of lanthanide dopants. These results open up a new field of hybrid optoelectronic devices and provide new opportunities for the electrically driven excitation sources based on lanthanide nanomaterials for biomedical and optoelectronic applications.
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Nov 2025
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I11-High Resolution Powder Diffraction
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Zhengyan
Lun
,
Alice J.
Merryweather
,
Amoghavarsha
Mahadevegowda
,
Shrinidhi S.
Pandurangi
,
Chao
Xu
,
Simon
Fairclough
,
Vikram
Deshpande
,
Norman A.
Fleck
,
Caterina
Ducati
,
Christoph
Schnedermann
,
Akshay
Rao
,
Clare P.
Grey
Open Access
Abstract: Extensive worldwide efforts have been made to understand the degradation behavior of layered Ni-rich LiNixMnyCo(1−x−y)O2 (NMC) cathodes. The majority of studies carried out to date have focused on thermodynamic perspectives and are conducted ex situ; operando investigations on aged materials, especially those that can resolve dynamic information in a single-particle level remain sparse, preventing the development of long-term stable NMCs. Here, we directly visualize the real-time Li-ion transport kinetics of aged Ni-rich single-crystal NMC under operando conditions and at single-particle level using a recently developed optical microscopy technique. For both fresh and aged particles, we identify Li-ion concentration gradients developing during the early stages of delithiation – resulting in a Li-rich core and Li-poor surface – as observed previously and attributed to low Li-ion diffusivity at high Li-occupancies. Critically, in contrast to fresh particles, the Li-ion gradients in aged particles become markedly asymmetric, with the Li-rich core shifted away from the center of mass of the particle. Using ex situ transmission electron microscopy, we show that cell aging produces an uneven build-up of a surface rocksalt layer. Supported by finite-element modelling, we attribute the asymmetric delithiation behavior of the aged particles to this uneven rocksalt layer, which impedes the Li-ion flux heterogeneously at the particle surface. Our results demonstrate a new mechanism that contributes to the capacity and rate degradation of Ni-rich cathodes, highlighting the importance of controlling the build-up of detrimental interfacial layers in cathodes and providing a rational for improving the long-term stability and rate capabilities of Ni-rich NMC cathodes.
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Mar 2025
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I09-Surface and Interface Structural Analysis
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Diamond Proposal Number(s):
[31918]
Open Access
Abstract: The discovery of ferroelectric phases in HfO2-based films has reignited interest in ferroelectrics and their application in resistive switching (RS) devices. This study investigates the pivotal role of electrodes in facilitating the Schottky-to-Ohmic transition (SOT) observed in devices consisting of ultrathin epitaxial ferroelectric Hf0.93Y0.07O2 (YHO) films deposited on La0.67Sr0.33MnO3-buffered Nb-doped SrTiO3 (NbSTO|LSMO) with Ti|Au top electrodes. These findings indicate combined filamentary RS and ferroelectric switching occurs in devices with designed electrodes, having an ON/OFF ratio of over 100 during about 105 cycles. Transport measurements of modified device stacks show no change in SOT when the ferroelectric YHO layer is replaced with an equivalent hafnia-based layer, Hf0.5Zr0.5O2 (HZO). However, incomplete SOT is observed for variations in the top electrode thickness or material, as well as LSMO electrode thickness. This underscores the importance of employing oxygen-reactive electrodes and a bottom electrode with reduced conductivity to stabilize SOT. These findings provide valuable insights for enhancing the performance of ferroelectric RS devices through integration with filamentary RS mechanism.
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Jan 2025
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E01-JEM ARM 200CF
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Diamond Proposal Number(s):
[32597, 28816]
Abstract: Niobium tungsten oxides are gaining attention as anodes for lithium-ion batteries due to their high volumetric energy storage densities obtained at high cycling rates. Two new niobium tungsten bronze structures, NbWO5.5 and β-Nb2WO8, were prepared with microwave-assisted solution-based methods at 800°C. These adopt a simple tetragonal tungsten bronze (TTB) and a √2 × √2 TTB superstructure, respectively. Nb3WO10.5 with a structure closely related to β-Nb2WO8 was formed at higher Nb:W ratios. Nb:W ≥ 4 compositions result in two-phase behavior forming Nb2O5 and Nb3WO10.5, while W-rich bronzes (Nb:W < 1) exhibited local domains of WO3 within the NbWO5.5 lattice. Diffraction and electron microscopy analysis revealed cation ordering in the bronzes at different length scales. The microwave synthesis method produced microporous spheres, with the high-Nb-content phases showing promising high-rate capabilities and long cycle lives, making them suitable for energy-storage applications. The microwave-assisted solution method holds potential for synthesizing complex oxide materials across diverse applications.
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Jul 2024
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Bolong
Zhang
,
Kieran D.
Richards
,
Beatrice E.
Jones
,
Abigail R.
Collins
,
Rosie
Sanders
,
Sarah R.
Needham
,
Pu
Qian
,
Amoghavarsha
Mahadevegowda
,
Caterina
Ducati
,
Stanley
Botchway
,
Rachel C.
Evans
Open Access
Abstract: Image contrast is often limited by background autofluorescence in steady-state bioimaging microscopy. Upconversion bioimaging can overcome this by shifting the emission lifetime and wavelength beyond the autofluorescence window. Here we demonstrate the first example of triplet-triplet annihilation upconversion (TTA-UC) based lifetime imaging microscopy. A new class of ultra-small nanoparticle (NP) probes based on TTA-UC chromophores encapsulated in an organic-inorganic host has been synthesized. The NPs exhibit bright UC emission (400-500 nm) in aerated aqueous media with a UC lifetime of ~1 μs, excellent colloidal stability and little cytotoxicity. Proof-of-concept demonstration of TTA-UC lifetime imaging using these NPs shows that the long-lived anti-Stokes emission is easily discriminable from typical autofluorescence. Moreover, fluctuations in the UC lifetime can be used to map local oxygen diffusion across the subcellular structure. Our TTA-UC NPs are highly promising stains for lifetime imaging microscopy, affording excellent image contrast and potential for oxygen mapping that is ripe for further exploitation.
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Aug 2023
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I11-High Resolution Powder Diffraction
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Diamond Proposal Number(s):
[28349]
Open Access
Abstract: Nickel-rich layered oxide cathodes such as NMC811 (LixNi0.8Mn0.1Co0.1O2) currently have the highest practical capacities of cathodes used commercially, approaching 200 mAh/g. Lithium is removed from NMC811 via a solid-solution behavior when delithiated to xLi > 0.10, maintaining the same layered (O3 structure) throughout as observed via operando diffraction measurements. Although it is possible to further delithiate NMC811, it is kinetically challenging, and there are significant side reactions between the electrolyte and cathode surface. Here, small format, NMC811-graphite pouch cells were charged to high voltages at elevated temperatures and held for days to access high states of delithiation. Rietveld refinements on high-resolution diffraction data and indexing of selected area electron diffraction patterns, both acquired ex situ, show that NMC811 undergoes a partial and reversible transition from the O3 to the O1 phase under these conditions. The O1 phase fraction depends not only on the concentration of intercalated lithium but also on the hold temperature and hold time, indicating that the phase transition is kinetically controlled. 1H NMR spectroscopy shows that the proton concentration decreases with O1 phase fraction and is not, therefore, likely to be driving the O3–O1 phase transition.
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Jun 2023
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I07-Surface & interface diffraction
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Yuqi
Sun
,
Lishuang
Ge
,
Linjie
Dai
,
Changsoon
Cho
,
Jordi
Ferrer Orri
,
Kangyu
Ji
,
Szymon J.
Zelewski
,
Yun
Liu
,
Alessandro J.
Mirabelli
,
Youcheng
Zhang
,
Jun-Yu
Huang
,
Yusong
Wang
,
Ke
Gong
,
May Ching
Lai
,
Lu
Zhang
,
Dan
Yang
,
Jiudong
Lin
,
Elizabeth M.
Tennyson
,
Caterina
Ducati
,
Samuel D.
Stranks
,
Lin-Song
Cui
,
Neil C.
Greenham
Diamond Proposal Number(s):
[30575]
Abstract: Perovskite light-emitting diodes (LEDs) have attracted broad attention due to their rapidly increasing external quantum efficiencies (EQEs)1,2,3,4,5,6,7,8,9,10,11,12,13,14,15. However, most high EQEs of perovskite LEDs are reported at low current densities (<1 mA cm−2) and low brightness. Decrease in efficiency and rapid degradation at high brightness inhibit their practical applications. Here, we demonstrate perovskite LEDs with exceptional performance at high brightness, achieved by the introduction of a multifunctional molecule that simultaneously removes non-radiative regions in the perovskite films and suppresses luminescence quenching of perovskites at the interface with charge-transport layers. The resulting LEDs emit near-infrared light at 800 nm, show a peak EQE of 23.8% at 33 mA cm−2 and retain EQEs more than 10% at high current densities of up to 1,000 mA cm−2. In pulsed operation, they retain EQE of 16% at an ultrahigh current density of 4,000 mA cm−2, along with a high radiance of more than 3,200 W s−1 m−2. Notably, an operational half-lifetime of 32 h at an initial radiance of 107 W s−1 m−2 has been achieved, representing the best stability for perovskite LEDs having EQEs exceeding 20% at high brightness levels. The demonstration of efficient and stable perovskite LEDs at high brightness is an important step towards commercialization and opens up new opportunities beyond conventional LED technologies, such as perovskite electrically pumped lasers.
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Mar 2023
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