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Yang C, Wei Q, Gong Y, Long M, Zhou G, Xing G, Wu B. Correlated Self-Trapped Excitons and Free Excitons with Intermediate Exciton-Phonon Coupling in 2D Mixed-Halide Perovskites. J Phys Chem Lett 2023; 14:10046-10053. [PMID: 37910791 DOI: 10.1021/acs.jpclett.3c02346] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2023]
Abstract
Low-dimensional lead halides have attracted increasing attention due to their potential application as single-component white-light emitters. These materials exhibit a complex emission spectral structure, ranging from free exciton narrowband emissions to self-trapped exciton broadband emissions. However, there is still no consensus for the underlying physical mechanism, especially in the spectrum with both narrowband and broadband emissions. Here we aim to elucidate the correlation between the emission spectrum and the exciton-phonon coupling in the mixed halide perovskite BA2Pb(BrxCl1-x)4. Our findings reveal that the interplay between exciton localization and delocalization results in an intermediate exciton-phonon coupling, leading to line shapes beyond the Huang-Rhys model for the self-trapped exciton. By incorporating the exciton motional effect, we establish a unified photophysical model describing the emission spectrum from the self-trapped exciton type to the free exciton type. These results provide essential insights into the mechanisms governing exciton-phonon interactions and offer ways to control white-light emission in two-dimensional perovskites.
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Affiliation(s)
- Cheng Yang
- Guangdong Provincial Key Laboratory of Optical Information Materials and Technology, Institute of Electronic Paper Displays, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou 510006, P. R. China
| | - Qi Wei
- Joint Key Laboratory of the Ministry of Education, Institute of Applied Physics and Materials Engineering, University of Macau, Avenida da Universidade, Taipa, Macao SAR 999078, China
| | - Yiyang Gong
- Guangdong Provincial Key Laboratory of Optical Information Materials and Technology, Institute of Electronic Paper Displays, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou 510006, P. R. China
| | - Mingzhu Long
- Guangdong Provincial Key Laboratory of Optical Information Materials and Technology, Institute of Electronic Paper Displays, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou 510006, P. R. China
| | - Guofu Zhou
- Guangdong Provincial Key Laboratory of Optical Information Materials and Technology, Institute of Electronic Paper Displays, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou 510006, P. R. China
| | - Guichuan Xing
- Joint Key Laboratory of the Ministry of Education, Institute of Applied Physics and Materials Engineering, University of Macau, Avenida da Universidade, Taipa, Macao SAR 999078, China
| | - Bo Wu
- Guangdong Provincial Key Laboratory of Optical Information Materials and Technology, Institute of Electronic Paper Displays, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou 510006, P. R. China
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Rego G. Temperature Dependence of the Thermo-Optic Coefficient of SiO 2 Glass. SENSORS (BASEL, SWITZERLAND) 2023; 23:6023. [PMID: 37447874 DOI: 10.3390/s23136023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/05/2023] [Revised: 06/17/2023] [Accepted: 06/27/2023] [Indexed: 07/15/2023]
Abstract
This paper presents a thorough analysis on the temperature dependence of the thermo-optic coefficient, dn/dT, of four bulk annealed pure-silica glass samples (type I-natural quartz: Infrasil 301; type II-quartz crystal powder: Heraeus Homosil; type III-synthetic vitreous silica: Corning 7980 and Suprasil 3001) from room temperature down to 0 K. The three/four term temperature dependent Sellmeier equations and respective coefficients were considered, which results from fitting to the raw data obtained by Leviton et al. The thermo-optic coefficient was extrapolated down to zero Kelvin. We have obtained dn/dT values ranging from 8.16 × 10-6 up to 8.53 × 10-6 for the four samples at 293 K and for a wavelength of 1.55 μm. For the Corning 7980 SiO2 glass, the thermo-optic coefficient decreases monotonically, from 8.74 × 10-6 down to 8.16 × 10-6, from the visible range up to the third telecommunication window, being almost constant above 1.3 μm. The Ghosh's model was revisited, and it was concluded that the thermal expansion coefficient only accounts for about 2% of the thermo-optic coefficient, and we have obtained an expression for the temperature behavior of the silica excitonic bandgap. Wemple's model was also analyzed where we have also considered the material dispersion in order to determine the coefficients and respective temperature dependences. The limitations of this model were also discussed.
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Affiliation(s)
- Gaspar Rego
- ADiT-LAB, Instituto Politécnico de Viana do Castelo, Rua Escola Industrial e Comercial Nun'Álvares, 4900-347 Viana do Castelo, Portugal
- Center for Applied Photonics, INESC TEC, Rua Dr. Roberto Frias, 4200-465 Porto, Portugal
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Manoj KM, Manekkathodi A. Light's interaction with pigments in chloroplasts: The murburn perspective. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY 2021. [DOI: 10.1016/j.jpap.2020.100015] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
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Cassidy A, James RL, Dawes A, Field D. Crystallites and Electric Fields in Solid Ammonia. ChemistryOpen 2020; 9:983-990. [PMID: 33024652 PMCID: PMC7528761 DOI: 10.1002/open.202000118] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2020] [Revised: 06/03/2020] [Indexed: 11/12/2022] Open
Abstract
Absorption spectra of vacuum-deposited films of ammonia have been obtained in the range 115 nm to 310 nm for a set of 15 deposition temperatures, Td, between 20 K and 80 K. Results focus upon the region 115 nm to 130 nm in overlapping D, E, F and G←X Rydberg transitions involving Wannier-Mott excitons. We identify two phases of ammonia, showing the solid to be polymorphic. Peak absorption wavelengths in the region of interest are found to shift to the red by 299 cm-1, for Td between 20 K to 50 K, and 1380 cm-1 for Td between 55 K to 80 K. Shifts provide evidence for the presence of spontaneously generated electric fields in these films, of values in excess of 108 V m-1 for Td of 20 K to 50 K to a few times 107 V m-1 for 55 K to 80 K. Results enable us to place a lower limit of 1.58 nm on the size of crystallites in the low temperature regime. This dimension represents 16 unit cells or 64 species, giving a more quantitative description than the nebulous term amorphous, as applied to solid ammonia. We also determine that crystallites formed in the high temperature regime contain, within ±20 %, 1688, 756 and 236 molecules of ammonia, respectively at Td of 65 K, 60 K and 55 K.
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Affiliation(s)
- Andrew Cassidy
- Department of Physics and Astronomy, Aarhus University, Ny Munkegade 120, 8000, Aarhus, Denmark
| | - Rachel L James
- School of Physical Sciences, The Open University, Walton Hall, Milton Keynes, MK7 6AA, UK
| | - Anita Dawes
- School of Physical Sciences, The Open University, Walton Hall, Milton Keynes, MK7 6AA, UK
| | - David Field
- Department of Physics and Astronomy, Aarhus University, Ny Munkegade 120, 8000, Aarhus, Denmark
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5
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Zatsepin AF, Buntov EA, Zatsepin DA, Kurmaev EZ, Pustovarov VA, Ershov AV, Johnson NW, Moewes A. Energy band gaps and excited states in Si QD/SiO x /R y O z (R = Si, Al, Zr) suboxide superlattices. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2019; 31:415301. [PMID: 31292291 DOI: 10.1088/1361-648x/ab30d6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
X-ray and optical spectroscopies were applied in order to study the band structure and electronic excitations of the SiO x /R y O z (R = Si, Al, Zr) suboxide superlattices. The complementary x-ray emission and absorption measurements allow for the band gap values for the SiO x layers to be established, which are found to have almost no dependency on the cation type R. It is determined that, after annealing, the stoichiometric factor x remains near 1.8 in all the systems under study, implying that the silicon quantum dot synthesis reaction is not fully completed. It is shown that the SiO x /Al2O3 multilayer contains octahedral structural motifs (SiO6) usually found in stishovite, whereas SiO x /SiO2 and SiO x /ZrO2 demonstrate an electronic structure similar to conventional silica. The intrinsic electronic excited states are examined by means of synchrotron-excited photoluminescence spectroscopy. Low-energy UV-excited luminescence of SiO x layers is found to have the same spectrum in all of the studied structures, while VUV-excited spectra strongly depend on the cation R. In these measurements, manifestations of 'slow' exciton-mediated and 'fast' defect-related luminescence are distinguished using nanosecond time resolution. It is shown that both mobile and bounded excitons appear in the suboxide layer under 6.2 eV and 5.8 eV irradiation and then relax radiatively through the triplet-singlet transition of the neighbouring oxygen-deficient centers. The complete picture of the optical excitation and relaxation processes in these materials is illustrated in a general diagram depicting electronic states.
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Affiliation(s)
- Anatoly F Zatsepin
- Institute of Physics and Technology, Ural Federal University, 620002 Yekaterinburg, Russia
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Kumar A, Mishra V, Warshi MK, Sati A, Sagdeo A, Kumar R, Sagdeo PR. Strain induced disordered phonon modes in Cr doped PrFeO 3. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2019; 31:275602. [PMID: 30893657 DOI: 10.1088/1361-648x/ab1195] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Room temperature optical absorption spectroscopy (OAS) and Raman spectroscopy measurements have been carried out in order to understand the effect of structural disorder on the electronic and phononic states. For this purpose, polycrystalline samples of Cr doped PrFeO3 have been prepared via wet chemical route. OAS analysis suggests the systematic scaling of electronic disorder with Cr doping; whereas, shifting in Raman line shapes and an increase in Raman line width has been observed with Cr doping. X-ray diffraction analysis clearly suggests the increase in structural disorders in the form of crystallographic strain with Cr doping, which is consistent with the broadening in Raman line shapes. The major contribution to Raman line width has been understood in terms of temperature independent terms i.e. structural disorder induced by doping. The generation of a new phonon mode at ~510 cm-1 has been observed and understood as a disorder phonon mode due to strain induced structural disorder. Moreover, a systematic correlation between crystallographic strain, Raman line width, disordered parameter (σ) and Urbach energy has been observed, which implies that structural disorder affects phononic as well as electronic states of the system. Such comparative study allows us to find the correlation between densities of tail states, structural disorders and anharmonic effects probed by Raman spectroscopy.
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Affiliation(s)
- Anil Kumar
- Material Research Laboratory, Discipline of Physics and MEMS, Indian Institute of Technology Indore, Indore 453552, India
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Malyi OI, Boström M, Kulish VV, Thiyam P, Parsons DF, Persson C. Volume dependence of the dielectric properties of amorphous SiO2. Phys Chem Chem Phys 2016; 18:7483-9. [DOI: 10.1039/c5cp06775h] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The dielectric properties of amorphous SiO2 and other SiO2 polymorphs are linked by simple volume dependence.
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Affiliation(s)
- Oleksandr I. Malyi
- Centre for Materials Science and Nanotechnology
- University of Oslo
- NO-0316 Oslo
- Norway
| | - Mathias Boström
- Centre for Materials Science and Nanotechnology
- University of Oslo
- NO-0316 Oslo
- Norway
| | - Vadym V. Kulish
- Department of Mechanical Engineering
- National University of Singapore
- Singapore 117576
- Singapore
| | - Priyadarshini Thiyam
- Department of Materials Science and Engineering
- Royal Institute of Technology
- SE-100 44 Stockholm
- Sweden
| | - Drew F. Parsons
- School of Engineering and Information Technology
- Murdoch University
- Murdoch
- Australia
| | - Clas Persson
- Centre for Materials Science and Nanotechnology
- University of Oslo
- NO-0316 Oslo
- Norway
- Department of Materials Science and Engineering
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Masuno A, Nishiyama N, Sato F, Kitamura N, Taniguchi T, Inoue H. Higher refractive index and lower wavelength dispersion of SiO 2 glass by structural ordering evolution via densification at a higher temperature. RSC Adv 2016. [DOI: 10.1039/c5ra25106k] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Silica glasses permanently densified at high temperatures show unexpected increase of both the refractive index and the Abbe number. Glasses densified at a higher temperature underwent homogeneous evolution of their intermediate structural ordering.
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Affiliation(s)
- A. Masuno
- Institute of Industrial Science
- The University of Tokyo
- Tokyo 153-8505
- Japan
| | - N. Nishiyama
- Deutsches Elektronen-Synchrotron (DESY)
- 22607 Hamburg
- Germany
- PRESTO
- Japan Science and Technology Agency
| | - F. Sato
- Nippon Electric Glass Co., Ltd
- Shiga 520-8639
- Japan
| | - N. Kitamura
- National Institute of Advanced Industrial Science and Technology
- Osaka 563-8577
- Japan
| | - T. Taniguchi
- National Institute for Materials Science
- Tsukuba 305-0044
- Japan
| | - H. Inoue
- Institute of Industrial Science
- The University of Tokyo
- Tokyo 153-8505
- Japan
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Zatsepin AF, Buntov EA, Kortov VS, Tetelbaum DI, Mikhaylov AN, Belov AI. Mechanism of quantum dot luminescence excitation within implanted SiO2:Si:C films. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2012; 24:045301. [PMID: 22214549 DOI: 10.1088/0953-8984/24/4/045301] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Results of the investigation of photoluminescence (PL) mechanisms for silicon dioxide films implanted with ions of silicon (100 keV; 7 × 10(16) cm(-2)) and carbon (50 keV; 7 × 10(15)-1.5 × 10(17) cm(-2)) are presented. The spectral, kinetic and thermal activation properties of the quantum dots (Si, C and SiC) formed by a subsequent annealing were studied by means of time-resolved luminescence spectroscopy under selective synchrotron radiation excitation. Independent quantum dot PL excitation channels involving energy transfer from the SiO(2) matrix point defects and excitons were discovered. A resonant mechanism of the energy transfer from the matrix point defects (E' and ODC) is shown to provide the fastest PL decay of nanosecond order. The critical distances (6-9 nm) of energy transport between the bulk defects and nanoclusters were determined in terms of the Inokuti-Hirayama model. An exchange interaction mechanism is realized between the surface defects (E(s)'-centres) and the luminescent nanoparticles. The peculiarities of an anomalous PL temperature dependence are explained in terms of a nonradiative energy transfer from the matrix excitons. It is established that resonant transfer to the luminescence centre triplet state is realized in the case of self-trapped excitons. In contrast, the PL excitation via free excitons includes the stages of energy transfer to the singlet state, thermally activated singlet-triplet conversion and radiative recombination.
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