MOLECULES
·
2018
·Vol. 23
·期 9
·2296
·
IF 3.098
Yao Huang,Run Yang,Shijie Xiong,Jian Chen,Xinglong Wu
Silicon carbide (SiC) has a large number of polytypes of which 3C-, 4H-, 6H-SiC are most common. Since different polytypes have different energy gaps and electrical properties, it is important to identify and characterize various SiC polytypes. Here, Raman scattering is performed on 6H-SiC micro/nanocrystal (MNC) films to investigate all four folded transverse optic (TO) and longitudinal optic (LO) modes. With increasing film thickness, the four folded TO modes exhibit the same frequency downshift, whereas the four folded LO modes show a gradually-reduced downshift. For the same film thickness, all the folded modes show larger frequency downshifts with decreasing MNC size. Based on plasmons on MNCs, these folded modes can be attributed to strong coupling of the folded phonons with plasmons which show different strengths for the different folded modes while changing the film thickness and MNC size. This work provides a useful technique to identify SiC polytypes from Raman scattering.Keywords:SiC micro/nanocrystals;plasmon–phonon coupling;folded phonons
研究领域:
材料科学
·
物理学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
Materials Today Chemistry
·
2025
·
IF 6.7
Kaihuang Huang,Shuaigang Ge,Chaowei Huang,Yongqi Yang,Bingsuo Zou
In recent years, metal halides have attracted much attention because of their fascinating optical properties. However, realizing an emission with efficient white light afterglow is still a great challenge. Here, high-purity Zn 2+ -doped CsCdCl 3 crystals have been synthesized by a hydrothermal method. Part of the Zn 2+ ions replace part of the Cd 2+ ions in the coplanar octahedron, so atomically confined excitons are formed around the coplanar octahedron. This exciton produces blue emission with a center wavelength of 422 nm at room temperature, but also produces weak STE at 595 nm. This is due to the dominance of confined exciton ( Cd CE) luminescence and suppression of intrinsic STE with PLQY reaching 44.53 %. Doping of Zn 2+ emits a white afterglow at room temperature. Raman and pyroelectric spectroscopic analyses show that the A 1g 246 cm −1 phonon mode plays an important role in the electron-phonon coupling process and dominates the afterglow luminescence process. In addition, white light emitting diodes (WLEDs) were fabricated with Zn 2+ doped CsCdCl 3 to show their potential in lighting applications.
研究领域:
材料科学
·
光学
✓ 已验证
产品关联
DOI
高影响因子
Optical Materials Express
·
2015
·Vol. 5
·期 9
·2069-2080
·
IF 2.844
Ping Zhou,Xiaosong Zhang,Lan Li,Xiaojuan Liu,Linlin Yuan,Xuguang Zhang
Different particle sizes of colloidal Mn doped ZnCuInS (Mn:ZCIS) nanocrystals were prepared with different reaction times in a noncoordinating solvent. Different test methods were used to reveal the successful incorporation of Mn2+ ion into ZCIS nanocrystals for obtaining the Mn d-state emission. We investigated the temperature-dependent PL spectra of Mn:ZCIS nanocrystals show a redshift with decreasing intensity at low temperature (20–300 K). The energy levels, FWHM of the PL peak and PL Intensity of nanocrystals with different diameters were investigated as a function of temperature in the range 20−300 K. We found that the variation of both energy level and PL peak broadening for Mn:ZCIS nanocrystals were most likely caused by the coupling of the carrier to acoustic phonon.
研究领域:
材料科学
·
光学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF LUMINESCENCE
·
2023
·
IF 3.6
Aochen Du,Xingke Zheng,Genzhuang Li,Yun Ye,Enguo Chen,Sheng Xu,Tailiang Guo
The lead-free double perovskite, increasingly sought for optoelectronic pursuits, is distinguished by its notable stability, optical properties, and non-toxic characteristic. An extensive inquiry into the structural and photoelectric properties of Cs 2 NaBiCl 6 at heightened temperatures was undertaken using experimental evaluations and theoretical computations. The compound Cs 2 NaBiCl 6 , synthesized using a hydrothermal technique, was confirmed via various analytical methods. Advanced techniques such as high-temperature X-ray diffraction, X-ray fluorescence, X-ray photoelectron spectroscopy, and selected area electron diffraction were employed for the investigation of its crystal structure. Further investigation of microstructure was undertaken using electron microscopes. High-temperature luminescence stability disclosed a high exciton binding energy of 326 meV. The Huang-Rhys factor (6.4) denotes a robust electron-phonon coupling effect and facile formation of self-trapped excitons (700 nm). Applied first principles render valuable insight into structural and photoelectric nuances, notably at escalated temperatures. Cs 2 NaBiCl 6 as an indirect bandgap semiconductor and details the experimental and theoretical bandgap, which exhibits an increasing trend before subsequently declining at elevated temperatures. These results strongly support the material's high-temperature stability, emphasizing its applicability in applications such as rare-earth-doped phosphors. The dynamic stability of the material, evidenced by its mechanical performance, further underscores its potential for application in photoelectric devices.
研究领域:
材料科学
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光学
✓ 已验证
DOI
高影响因子
Advanced Optical Materials
·
2024
·Vol. 12
·期 20
·2400184
·
IF 8
Yue Li,Haolin Lu,Rui Yun,Huanxin Yang,Yuling Liu,Zhaoyu Wang,Song Wang,Guankui Long,Xiyan Li
Lead-free perovskites exhibit unique crystal structures and optical properties due to their low-dimensional structure. However, the 0D structure of Cs 2 InCl 5 ·H 2 O usually demonstrates poor optical properties at room temperature due to their extremely strong electron–phonon coupling interaction. In this study, a doping strategy is employed by introducing Pb 2+ into Cs 2 InCl 5 ·H 2 O, resulting in the achievement of an efficient broadband blue emission, with a photoluminescence quantum yield (PLQY) of 58%. The temperature-dependent PL spectra reveal that the efficient emission is attributed to the weakening of the electron–phonon coupling strength in the lattice and the inhibition of the phonon-assisted non-radiative recombination process through Pb 2+ doping. The validity of this deduction is further corroborated by the results of the Raman spectra. The results of the first-principle calculation demonstrate that the broadband emission originates from multiple emission paths in In 3+ and Pb 2+ polyhedrons. In addition, Pb 2+ -doped Cs 2 InCl 5 ·H 2 O can realize the transformation from sky-blue emission to deep-blue emission by absorbing water in the air. Remarkably, this change is reversible during the heating–cooling cycles, demonstrating excellent optical stability with repeatable recyclability.
研究领域:
材料科学
·
光学
✓ 已验证
产品关联
DOI
高影响因子
ADVANCED FUNCTIONAL MATERIALS
·
2022
·Vol. 32
·期 22
·2111338
·
IF 19.924
Liangling Wang,Wei Zheng,Francesco Vitale,Xiangzhou Zhang,Xiuling Li,Yanchen Ji,Zhen Liu,Omid Ghaebi,Christian T. Plass,Robert Domes,Torsten Frosch,Giancarlo Soavi,Elke Wendler,Yuhai Zhang,Carsten Ronning
Alloyed lead-free double perovskites display intense photoluminescence, are environmentally friendly, and their devices show long-term operation. Thanks to these properties, which make them excellent warm white-emitting materials, they have recently received great attention in lighting applications. An important factor to tune the optical properties of alloyed lead-free double perovskites is the presence of self-trapped excitons. Here, it is demonstrated that in lead-free double perovskites, the strong electron–phonon coupling plays a crucial role in the generation of self-trapped excitons. The strong electron–phonon coupling is confirmed by a large Huang–Rhys factor and by the presence of multiphonon transitions. In particular, sharp emission lines superimposed on the broad photoluminescence emission band of one of these samples (Cs 2 Ag 0.6 Na 0.4 InCl 6 0.5%Bi) are observed; these are due to the strong coupling of longitudinal-optical phonons with excited electronic states caused by the tetragonally distorted AgCl 6 octahedrons. Such a strong coupling of longitudinal-optical phonons to electrons can effectively modulate the photophysical properties of alloyed double perovskites, and its understanding is, thus, of paramount importance for the design of future optoelectronic devices.
研究领域:
材料科学
·
光学
✓ 已验证
产品关联
DOI
高影响因子
Journal of Physical Chemistry C
·
2022
·
IF 4.177
Hui Peng,Ye Tian,Xinxin Wang,Tiantian Dong,Zongmian Yu,Yonghao Xiao,Zhenheng Zhang,Jianping Wang,Bingsuo Zou
Recently, low-dimensional metal halides (LDMHs) have attracted tremendous attention due to their fascinating optoelectronic properties. Here, we report an organic–inorganic hybrid Cu(I)-based metal halide of (TPA)CuCl2 (TPA+ = tetrapropylammonium cation), where the isolated [CuCl2]− units are surrounded by TPA+, thus forming a zero-dimensional block. Moreover, the as-synthesized compound shows a broad green emission with a photoluminescence (PL) quantum efficiency of 91.8% and a large Stokes shift of 230 nm, stemming from the self-trapped exciton (STE) transition. Variable-temperature Raman spectra reveal that there is a strong anharmonic electron–phonon coupling in (TPA)CuCl2, which provides clear evidence for the formation of STEs, and this is also supported by the temperature-dependent PL spectra of (TPA)CuCl2. Moreover, it was found that TPA+ not only works as a ligand but also participates in the STE emission. Our results provide a clear statement that the formation of the STE is related not only to the low-frequency phonon of [CuCl2]− clusters but also to the mid-infra vibration of organic molecules, which promotes the understanding of the emission mechanism of LDMHs.
研究领域:
材料科学
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光学
·
物理化学
✓ 已验证
产品关联
DOI
高影响因子
Micromachines
·
2022
·Vol. 13
·期 3
·443
·
IF 3.523
Nur Diyana Halim,Muhammad Safwan Zaini,Zainal Abidin Talib,Josephine Ying Chyi Liew,Mazliana Ahmad Kamarudin
The temperature dependence of photoluminescence (PL) emission is a valuable tool for investigating carrier localization, recombination, and carrier–phonon interactions. Herein, electron–phonon couplings in lead sulfide (PbS) quantum dots (QDs) and lead sulfide/manganese tellurite (PbS/MnTe) QDs is reported. The effect of temperature on the PL emission of PbS and PbS/MnTe was explored within a temperature range of 10 to 300 K. When temperature increased, PL emission was blue-shifted due to the confinement effect. The gradual broadening of the full width at half maximum (FWHM) with increasing temperature indicates electron–phonon interactions. An analysis based on the Boson model revealed that the values of the exciton acoustic phonon coupling coefficient, σ, and temperature-dependent linewidth, γ, for PbS/MnTe were larger than those for PbS, indicating stronger exciton longitudinal-optical–phonon coupling in the compound structure.Keywords:electron–phonon coupling;confinement;photoluminescence;quantum dots
研究领域:
材料科学
·
物理学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
SPECTROCHIMICA ACTA PART A-MOLECULAR AND BIOMOLECULAR SPECTROSCOPY
·
2023
·
IF 4.4
Zhenggang Zou,Tingting Guo,Guoliang Gong,Fulin Lin,Yijian Sun,Jianhui Huang,Jinsheng Liao,Herui Wen
The partially and equivalent substitution of La + Mg → Sr + Al in SrAl 12 O 19 lattice is an effective strategy to provide trivalent sites, reduce the site occupation splitting of Al and stabilize the entire lattice. When excited by 397 nm, the Eu 3+ activated La, Mg:SrAl 12 O 19 (ASL) phosphor shows intense linear emission through the 5 D 0 → 7 F 4 transition at 707 nm when compared with SrAl 12 O 19 :Eu 3+ . Especially, the Eu, Mg co-doped Sr 1-x La x Mg x Al 12-x O 19 with certain amount of x = 1/3 exhibits the significant intense photoluminescence, which was demonstrated through a lattice evolutional model. Eu 2+ in the host with 1/3 ratio of (La, Mg) substitution shows broad blue emission and as short fluorescence lifetime as 248 ns. The temperature-depended fluorescence quenching behavior confirms the essence of strong electric-phonon coupling originated from distorted and polarized crystal field around Eu 2+ /Sr 2+ site. Basing on site regulation of SrAl 12 O 19 matrix, our study provides a reference for exploration on efficient rare earth ions activated luminescent laser or scintillation materials.
研究领域:
材料科学
·
光学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
ACS Applied Nano Materials
·
2024
·
IF 5.3
Yubin Zhao,Xing Cao,Huanhui Chen,Ya Liu,Liubiao Zhong,Yejun Qiu
Low-dimensional metal halides are favored for optoelectronic device applications due to their strong electron–phonon coupling capability, which produces exciton self-trapping and broadband emission optoelectronic properties. Conventional methods for enhancing electron–phonon coupling involve the introduction of permanent defects or lattice distortions that inhibit the intrinsic structure and properties. In this work, we report that Cu-doped CsPb2Br5 nanocrystals exhibit broadband red emission with a high Stokes shift, a long fluorescence lifetime (9.27 μs), and a high photoluminescence quantum yield (∼ 36%) in the visible to near-infrared spectral range (∼550 to 825 nm). At the same time, the fact that the emission spectrum is independent of the excitation wavelength and the excitation spectrum is independent of the emission wavelength, together with the similarity of the decay kinetics, suggests that the broad-band emission has intrinsic properties. The soft vibrational modes of Raman spectroscopy indicate the softness of the lattice and the highly anharmonic character of the structure on the global and local scales. These properties lead to short-range elastic lattice deformation of Cu/CsPb2Br5 nanocrystals upon photoexcitation by strong electron–phonon coupling, resulting in self-trapped exciton emission. This method of doping-induced local distortion and exciton self-capture provides a way to improve the properties of the optoelectronic materials. Meanwhile, the fluorescence change in the crystal structure from CsPbBr3 to CsPb2Br5 can also be used for anticounterfeiting inks. Therefore, CsPb2Br5 crystals have promising applications in solid-state lighting and optoelectronic devices.
研究领域:
材料科学
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光学
·
固体物理
✓ 已验证
产品关联
DOI
高影响因子
CHINESE PHYSICS LETTERS
·
2024
·
IF 3.5
Longfu Li,Lei Shi,Lingyong Zeng,Kuan Li,Peifeng Yu,Kangwang Wang,Chao Zhang,Rui Chen,Zaichen Xiang,Yunwei Zhang,Huixia Luo
Chemical doping is a critical factor in the development of new superconductors or optimizing the superconducting transition temperature (Tc) of the parent superconducting materials. Herein, a new simple urea approach is developed to synthesize the N-doped α-Mo2C. Benefiting from the simple urea method, a broad superconducting dome is found in the Mo2C1-xNx (0 ≤ x ≤ 0.49) compositions. XRD results show that the structure of α-Mo2C remains unchanged and that there is a variation of lattice parameters with nitrogen doping. Resistivity, magnetic susceptibility, and heat capacity measurement results confirm that the superconducting transition temperature (Tc) was strongly increased from 2.68 K (x = 0) to 7.05 K (x = 0.49). First-principles calculations and our analysis indicate that increasing nitrogen doping leads to a rise in the density of states at the Fermi level and doping-induced phonon softening, which enhances electron-phonon coupling. This results in an increase in Tc and a sharp rise in the upper critical field. Our findings provide a promising strategy for fabricating transition metal carbonitrides and provide a material platform for further study of the superconductivity of transition metal carbides.
研究领域:
材料科学
·
凝聚态物理
✓ 已验证
DOI
高影响因子
Photonics Research
·
2019
·Vol. 7
·期 8
·837-846
·
IF 5.522
Ying Zhang,Haiou Zhu,Taiwu Huang,Zongpeng Song,Shuangchen Ruan
Perovskite quantum dots (QDs) are of great interest due to their outstanding optoelectronic properties and tremendous application potential. Improving photoluminescence (PL) spectra in all-inorganic perovskite QDs is of great importance for performance enhancement. In this work, the PL quantum yield of the CsPbBr3 perovskite QDs is enhanced from 70% to 95% with increasing radiation pressure. Such enhancement is attributed to the increased binding energy of self-trapped excitons (STEs) upon radiation pressure, which is consistent with its blue-shifted PL and other characterization results. Furthermore, we study ultrafast absorption spectroscopy and find that the dynamics of relaxation from free excitons to STEs in radiation pressure CsPbBr3 QDs is ascribed to stronger electron–phonon coupling in the contracted octahedral structure. It is further demonstrated that radiation pressure can boost the PL efficiency and explore effectively the relationship between the structure and optical properties.
研究领域:
材料科学
·
光学
✓ 已验证
产品关联
DOI
高影响因子
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