B18-Core EXAFS
|
Yuan
Liao
,
Yang
Fu
,
Fengzhan
Sun
,
Yuanshen
Wang
,
David C.
Lloyd
,
Zhiyong
Zhao
,
Zipei
Wan
,
Federico
Grillo
,
Arvydas
Ruseckas
,
Edward
Ogugu
,
John T. S.
Irvine
Open Access
Abstract: As the global energy landscape shifts to a green hydrogen economy, efficient and stable visible-light photocatalysts are increasingly central to optimizing solar-to-hydrogen conversion. Here, a Sr-site-deficient perovskite photocatalyst (R-Pt/Sr0.95Ti0.9Cr0.1O3-δ) was synthesised by a solid-state method, followed by Pt impregnation and hydrogen reduction post treatment. The introduction of A-site deficiency effectively tunes the band structure and facilitates hydrogen evolution, doubling activity compared to stoichiometric analogs. Besides, A-site deficiency reduces overall cation charge and promotes Cr4+ formation. Through spectroscopy and thermal analysis, Cr4+ was identified in the Sr0.95Ti0.9Cr0.1O3-δ perovskite, revealing unexplored oxidation state dynamics. Upon reduction, Cr4+ converts to Cr3+, creating oxygen vacancies and eliminating hole-trap sites. The resulting synergistic active sites greatly boost photocatalytic hydrogen evolution. Specifically, the R-Pt/Sr0.95Ti0.9Cr0.1O3-δ achieved 120.46 μmol/gcat/h under full spectrum and 68.66 μmol/gcat/h under visible light (λ ≥ 420 nm), representing twice and 5 times enhancements relative to stoichiometric R-Pt/SrTi0.9Cr0.1O3-δ and unreduced Pt/Sr0.95Ti0.9Cr0.1O3-δ in visible light separately. This work demonstrates that combining A-site engineering and valence-state modulation provide a helpful strategy for designing high-performance visible-light photocatalysts.
|
Feb 2026
|
|
I07-Surface & interface diffraction
|
Xinyi
Shen
,
Wing Tung
Hui
,
Shuaifeng
Hu
,
Fengning
Yang
,
Junke
Wang
,
Jin
Yao
,
Atse
Louwen
,
Bryan Siu Ting
Tam
,
Lirong
Rong
,
David P.
Mcmeekin
,
Kilian
Lohmann
,
Qimu
Yuan
,
Matthew C.
Naylor
,
Manuel
Kober-Czerny
,
Seongrok
Seo
,
Philippe
Holzhey
,
Karl-Augustin
Zaininger
,
M. Greyson
Christoforo
,
Perrine
Carroy
,
Vincent
Barth
,
Fion Sze Yan
Yeung
,
Nakita K.
Noel
,
Michael
Johnston
,
Yen-Hung
Lin
,
Henry J.
Snaith
Diamond Proposal Number(s):
[39532]
Open Access
Abstract: Vacuum-based deposition is a scalable, solvent-free industrial method ideal for uniform coatings on complex substrates. However, all-vacuum-deposited perovskite solar cells fabricated by thermal evaporation trail solution-processed counterparts in efficiency and stability due to film quality challenges, necessitating advancement and improved understanding. Here, we report a co-evaporation route for 1.67-eV wide-bandgap perovskites by introducing a PbCl2 co-source to optimize film quality. We promote perovskite formation with pronounced (100) ‘face-up’ orientation and deliver a certified all-vacuum-deposited solar cell with 18.35% efficiency (19.3% in the laboratory) for 0.25-cm2 devices (18.5% for 1-cm2 cells). These cells retain 80% of peak efficiency after 1,080 h under the ISOS-L-2 protocol. Leveraging operando hyperspectral imaging, we provide spatiotemporal spectral insight into halide segregation and trap-mediated recombination, correlating microscopic luminescence features with macroscopic device performance while distinguishing radiative from non-ideal recombination channels. We further demonstrate 27.2%-efficient 1-cm2 evaporated perovskite-on-silicon tandem cells and outdoor stability of all-vacuum-deposited tandems in Italy, retaining ~80% initial performance after eight months.
|
Feb 2026
|
|
I15-Extreme Conditions
|
Lecheng
Zhang
,
Juncheng
Pan
,
Jiayi
Wen
,
Jiajun
Shi
,
Ziqi
Yang
,
Bing
Wang
,
Annette K.
Kleppe
,
Egor
Koemets
,
Ilkan
Calisir
,
Yizhe
Li
,
David A.
Hall
Diamond Proposal Number(s):
[34938]
Open Access
Abstract: BiFeO3-BaTiO3 (BF-BT) ceramics are important lead-free ferroelectric materials, which are attracting attention due to their high Curie temperatures. In the present study, the effects of annealing at intermediate temperatures on the structure and ferroelectric hardening effects in Ti-doped BF-BT ceramics are investigated. It is shown that enhanced ferroelectric and piezoelectric properties are obtained by air-quenching. After subsequent annealing for 200 hours at temperatures in the range from 500 to 600 °C, the ferroelectric hysteresis loops became constricted due to a strong domain stabilisation effect. The ferroelectric internal bias field increased to an outstanding value of 5 kV mm-1 in a poled-annealed specimen. Analysis of the extrinsic (domain switching) and intrinsic (lattice strain) contributions to electro-strain by in-situ x-ray diffraction indicated that domain switching is dominant in the quenched BF-BT ceramic, but the domain orientation fraction under high electric field was reduced dramatically, from approximately 80% to 25%, after annealing.
|
Feb 2026
|
|
E02-JEM ARM 300CF
|
Jaeho
Lee
,
Wengang
Huang
,
Xiangyi
Zha
,
Xuemei
Li
,
Zixi
Xie
,
Peng
Chen
,
Chenghan
Sun
,
Muhammad Yazid
Bin Zulkifli
,
Sang T.
Pham
,
Bun
Chan
,
Marija
Švegovec
,
Atul
Shukla
,
Junyong
Zhu
,
Rijia
Lin
,
Nicholas M.
Bedford
,
Vicki
Chen
,
Sean
Collins
,
Andraž
Krajnc
,
Anthony K.
Cheetham
,
Lianzhou
Wang
,
Jingwei
Hou
Diamond Proposal Number(s):
[26822]
Open Access
Abstract: Developing quantum dots (QDs) with robust and stable photoluminescence are critical for the advancement of optical nanomaterials. However, QD synthesis still usually involves complex nucleation, growth, surface capping, and separation procedures. Herein, we present an approach to generating embedded PbI2 QDs in situ within the matrix of a metal–organic framework (MOF) glass. This is achieved by controllable decomposition of an optoelectronically inactive δ-phase organic lead halide perovskite (OLHP) within the MOF glass, where the high-temperature MOF melt alters the degradation pathway through interfacial bonding and dissolution effects, effectively preventing PbI2 aggregation and passivating the resulting QDs. The resulting composite exhibits high-quality, narrow line width photoluminescence at room temperature, alongside remarkable stability under ambient conditions. This innovative approach offers a sustainable and efficient route for QD generation, underscoring the potential of MOF glass-based composites in optoelectronic applications.
|
Jan 2026
|
|
I15-1-X-ray Pair Distribution Function (XPDF)
|
Caleb J.
Bennett
,
Neha
Bura
,
Frederick P.
Marlton
,
Wen Liang
Tan
,
Tobias A.
Bird
,
Pablo
Botella
,
Peijie
Zhang
,
Benedito Donizeti
Botan-Neto
,
Jose Luis
Rodrigo Ramon
,
Catalin
Popescu
,
Frederico
Alabarse
,
Daniel
Errandonea
,
Brendan J.
Kennedy
Diamond Proposal Number(s):
[36827]
Abstract: A variable temperature X-ray total-scattering study of K2IrCl6 reveals compelling evidence for local symmetry breaking in this material. While the average crystal structure remains cubic down to 11 K, consistent with earlier reports, large anisotropic chloride displacements suggest short-range distortions of the IrCl6 octahedra. Pair distribution function analysis confirms that the local structure is better described by a monoclinic P21/n model featuring a mix of in-phase and out-of-phase octahedral tilts. This behavior mirrors observations in related K2MX6 halides, where thermally driven cubic-to-monoclinic transitions occur. High-pressure synchrotron measurements further reveal two structural transitions: cubic Fm3̅m to tetragonal P4/mnc at 12.0 GPa, and tetragonal to monoclinic P21/n at 15.1 GPa. Both transitions are reversible on decompression. Lattice parameter refinements indicate anisotropic compression with the bulk modulus increasing dramatically from 23 GPa in the cubic phase to 121 GPa in the monoclinic structure. These results demonstrate that both temperature reduction and applied pressure drive K2IrCl6 toward lower-symmetry phases. Overall, this study provides the first direct local-structure evidence of symmetry breaking in K2IrCl6 and highlights the complex interplay among pressure, temperature, and local structure in vacancy-ordered double perovskites.
|
Jan 2026
|
|
E02-JEM ARM 300CF
|
Woo Hyeon
Jeong
,
Junzhi
Ye
,
Jongbeom
Kim
,
Rui
Xu
,
Xinyu
Shen
,
Chia-Yu
Chang
,
Eilidh L.
Quinn
,
Hyungju
Ahn
,
Myoung Hoon
Song
,
Peter D.
Nellist
,
Henry J.
Snaith
,
Yunwei
Zhang
,
Bo Ram
Lee
,
Robert L. Z.
Hoye
Diamond Proposal Number(s):
[40059]
Open Access
Abstract: The anisotropy of perovskite nanoplatelets (PeNPLs) opens up many opportunities in optoelectronics, including enabling the emission of linearly polarized light. But the limited stability of PeNPLs is a pressing challenge, especially for red-emitting CsPbI3. Herein, we address this limitation by alloying formamidinium (FA) into the perovskite cuboctahedral site. Unlike Cs/FA alloying in bulk thin films or nanocubes, FA incorporation in nanoplatelets requires meticulous control over the reaction conditions, given that nanoplatelets are obtained in kinetically-driven growth regimes instead of thermodynamically-driven conditions. Through in-situ photoluminescence (PL) measurements, we find that excess FA leads to uncontrolled growth, where phase impurities and nanoplatelets of multiple thicknesses co-exist. Restricting the FA content to up to 25% Cs substitution enables monodisperse PeNPLs, and increases the PL quantum yield (from 53% to 61%), exciton lifetime (from 18 ns to 27 ns), and stability in ambient air (from ~2 days to >7 days) compared to CsPbI3. This arises due to hydrogen bonding between FA and the oleate and oleylammonium ligands, anchoring them to the surface to improve optoelectronic properties and stability. The reduction in non-radiative recombination, improvement in the nanoplatelet aspect ratio, and higher ligand density lead to FA-containing PeNPLs more effectively forming edge-up superlattices, enhancing the PL degree of linear polarization from 5.1% (CsPbI3) to 9.4% (Cs0.75FA0.25PbI3). These fundamental insights show how the stability limitations of PeNPLs could be addressed, and these materials grown more precisely to improve their performance as polarized light emitters, critical for utilizing them in next-generation display, bioimaging, and communications applications.
|
Jan 2026
|
|
|
|
Abstract: The low-temperature performance of mixed-composition perovskite solar cells (PSCs) reflects the complex interplay among thermal effects, bandgap renormalization, and structural phase behavior. Temperature-dependent structural, optical, and electrical measurements reveal a maximum power conversion efficiency at 263 K, which coincides with the onset of the cubic-tetragonal phase coexistence. At this temperature, symmetry lowering is observed, accompanied by a split emission band and increased current–voltage hysteresis, consistent with structural heterogeneity. Device simulations show that any benefit from mixed-phase band alignment is conditional on effective interphase passivation. Consequently, the mixed phase is best described as a loss-minimum condition at well-passivated cubic–tetragonal interphases with stable collection. Our findings identify a narrow mixed-phase window in which phase coexistence couples to the optoelectronic response and enhances the device performance, providing fundamental insight into temperature-dependent structure–property relations in hybrid perovskites.
|
Dec 2025
|
|
E02-JEM ARM 300CF
|
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.
|
Dec 2025
|
|
I15-1-X-ray Pair Distribution Function (XPDF)
|
Jamie L.
Cleron
,
Chih-Yi
Chen
,
Feng
Pan
,
Santanu
Saha
,
Frederick P.
Marlton
,
Robert M.
Stolz
,
Jiayi
Li
,
Jennifer A.
Dionne
,
Fang
Liu
,
Marina R.
Filip
,
Hemamala I.
Karunadasa
Diamond Proposal Number(s):
[40486]
Open Access
Abstract: Self-assembly affords simpler synthetic routes to heterostructures compared with manual layer-by-layer stacking, yet controlling interlayer twist angles in a bulk solid remains an outstanding challenge. We report two new single-crystal heterostructures: (Sn2Cl2)(CYS)2SnCl4 (CYS = +NH3(CH2)2S–; Sn_CYS) and (Sn2Cl2)(SeCYS)2SnCl4 (SeCYS = +NH3(CH2)2Se–; Sn_SeCYS) synthesized in solution, with alternating perovskite and intergrowth layers. Notably, compared to the recently reported lead analog, (Pb2Cl2)(CYS)2PbCl4 (Pb_CYS), the tin heterostructures feature a twist between the perovskite and intergrowth layers. We trace this twist to local distortions at the Sn centers, which change the interfacial lattice-matching requirements compared to those of the Pb analog. Electronic band structure calculations show that the striking differences in the relative energies of perovskite- and intergrowth-derived bands in Sn_CYS and Pb_CYS arise from structural and not compositional differences. The structural anisotropy of Sn_CYS is also reflected in a large in-plane photoluminescence linear anisotropy ratio. Interfacial strain further affords differential incorporation of Pb into the perovskite and intergrowth layers of the Sn heterostructures, resulting in redshifted optical absorption onsets. Thus, we posit that local structural distortions may be exploited to manipulate the twist angle and interfacial strain in bulk heterostructures, providing a new handle for tuning the band alignments of bulk quantum-well electronic structures.
|
Dec 2025
|
|
|
|
Open Access
Abstract: Of all the oxides of osmium, Ba2NaOsO6 is the only one with a substantial ferromagnetic moment. A fresh theoretical study of the double perovskite is accomplished using a different magnetic symmetry, which embraces all relevant published structural information, and an atomic model of a Kramers doublet formed by the single osmium d electron. It possesses symmetry demanded by the Wyckoff position assigned to Os in a canted ferromagnet. Whereupon, magnetic moments in the paramagnetic and magnetically ordered states of Ba2NaOsO6 are unified. Analytic x-ray magnetic dichroic signals (XMCD) at osmium L2 and L3 absorption edges are presented, and shown to agree with hitherto unexplained recent measurements [Agrestini et al. Phys. Rev. Lett. 133, 066501 (2024)].
|
Dec 2025
|
|
