| 1. |
- Haw, Shu Chih, et al.
(författare)
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Single antiferromagnetic axis of Fe in orthorhombic YMn0.5Fe0.5O3 films observed by x-ray magnetic linear dichroism
- 2019
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Ingår i: Journal of Alloys and Compounds. - : Elsevier BV. - 0925-8388. ; 780, s. 79-84
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Tidskriftsartikel (refereegranskat)abstract
- The electronic and magnetic structure of orthorhombic (o-) YMn0.5Fe0.5O3 (YMFO) epitaxial film (space group Pbnm) deposited on the YAlO3 (010) substrate have been investigated using linear polarization-dependent x-ray absorption spectroscopy and magnetization measurements. The magnetic-ordering temperature of around 280 K is observed in o-YMFO film. The x-ray absorption spectra at the Fe-K and the Mn-K edges indicate the existence of anisotropic crystal field in o-YMFO film, with the longest and shortest Fe–O and Mn–O bonds tend to align with the crystallographic b- and a-axis, respectively, whereas the medium Fe(Mn)–O bond is aligned with the c-axis. The experimental x-ray magnetic linear dichroism at the Fe-L2 edges demonstrate an unusual single antiferromagnetic axis of Fe3+ ions below magnetic-ordering temperature, while a multi antiferromagnetic axis is generally observed in o-RFeO3 (R = rare earth) thin films. Our configuration-interaction cluster calculations also reveal that the single antiferromagnetic axis of the Fe sublattice is aligned with the b-axis in o-YMFO film, whereas it is directed along the a-axis in the bulk o-YFeO3.
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| 2. |
- Fan, Xiangyang, et al.
(författare)
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Phosphine oxide modulator-ameliorated hole injection for blue perovskite light-emitting diodes
- 2023
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Ingår i: Journal of Materials Chemistry A. - : ROYAL SOC CHEMISTRY. - 2050-7488 .- 2050-7496. ; 11:38, s. 20808-20815
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Tidskriftsartikel (refereegranskat)abstract
- Despite the enormous developments in perovskite light-emitting diodes (PeLEDs) recently, obtaining efficient blue PeLEDs is still considered a critical challenge due to the non-radiative recombination and unbalanced charge injection caused by the unmatched carrier mobility and the deep hole-injection barrier between the hole-transport layer (HTL) and the emissive layer (EML). Herein, we incorporate tris(4-trifluoromethylphenyl)phosphine oxide (TMFPPO), obtained through a facile oxidation synthesis process, into poly(9-vinylcarbazole) (PVK). TMFPPO incorporation modulated the energy level and hole mobility of the binary-blend HTLs to eliminate the hole-injection barrier and balance the charge injection within the EML. Consequently, the blue PeLEDs with blended HTL presented an external quantum efficiency (EQE) of 7.23% centred at 477 nm, which was much higher than the EQE of a PVK device (4.95%). Our results demonstrate that modulating the energy level and charge injection of the HTL in the device is a promising method for obtaining efficient blue PeLEDs. TMFPPO is developed and incorporated into PVK to modulate the hole mobility and energy level of the hole-transport layer, giving rise to a barrier-free blue perovskite light-emitting diode and an enhancement of the EQE from 4.95 to 7.23% at 477 nm.
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| 3. |
- Kim, Min-Jeong, et al.
(författare)
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Independent enhancement of the in-plane Seebeck effect in 2D PtSe2/PtSe2 homostructures via a facile interface tuning method
- 2024
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Ingår i: Acta Materialia. - : Elsevier. - 1359-6454 .- 1873-2453. ; 268
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Tidskriftsartikel (refereegranskat)abstract
- Atomically thin two-dimensional (2D) transition-metal dichalcogenide (TMDC) films have emerged as promising semiconducting materials for use in thermoelectric (TE) applications. However, the utilization of such materials remains challenging owing to the relatively high intrinsic resistance as the size of the TMDC thin films increases to the centimeter scale. These 2D TMDC films can also form vertically stacked homo- or heterostructures at large interfaces with other 2D TMDC films, resulting in unique TE properties at room temperature. This article reports on the in-plane TE properties when the interfaces formed within a PtSe2/PtSe2 (3 nm/3 nm) homostructure are modulated as a function of O2 plasma treatment time. The results show enhanced Seebeck coefficients compared with that of the single-layer PtSe2 with the same thickness. The independent enhancement in the Seebeck coefficient while keeping the electrical conductivity leads to a substantial increase in the power factor. Such extra Seebeck voltage in 2D PtSe2/PtSe2 homostructures is mainly as a result of momentum exchange by charge carriers caused by the temperature gradient in the vertical direction, which occurs in-plane Seebeck coefficient measurements, at the interface between the PtSe2 layers in the in-plane temperature gradient along the samples. These results resemble the characteristics of the phonon drag effect at low temperatures, which can independently increase the Seebeck coefficient at room temperature.
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