Pub Date : 2024-10-22DOI: 10.1016/j.jlumin.2024.120951
Shazma Ali, Muhammad Usman
The investigation of the optoelectronic performance of AlGaN-based ultraviolet-C (UV-C) micro light-emitting diodes (μLEDs) emitting at 273 nm is carried out numerically by reducing the chip area from large LED (300 × 300 μm2) to μLED (25 × 25 μm2). However, due to the high surface to volume ratio of μLED, surface recombination becomes dominant that is generated due to robust sidewall defects. The enhanced current spreading in μLED further affects the carrier injection in the active region as the electrons and holes are captured by sidewall defects. These effects are more dominant at low current density in μLED while at high current density, the sidewall defects get saturated, and the surface recombination weakens. Various optimization strategies, such as quantum wells (QWs) width, quantum barriers (QBs) width, and QW number are carried out to study the effect on the performance of 25 × 25 μm2 UV-C μLED. These optimization strategies at low current density (0.1 A/cm2) further improved the electrical/optical properties of AlGaN-based UV-C μLEDs.
{"title":"Dimensional downscaling and quantum engineering: A path to high-performance micro-LEDs","authors":"Shazma Ali, Muhammad Usman","doi":"10.1016/j.jlumin.2024.120951","DOIUrl":"10.1016/j.jlumin.2024.120951","url":null,"abstract":"<div><div>The investigation of the optoelectronic performance of AlGaN-based ultraviolet-C (UV-C) micro light-emitting diodes (μLEDs) emitting at 273 nm is carried out numerically by reducing the chip area from large LED (300 × 300 μm<sup>2</sup>) to μLED (25 × 25 μm<sup>2</sup>). However, due to the high surface to volume ratio of μLED, surface recombination becomes dominant that is generated due to robust sidewall defects. The enhanced current spreading in μLED further affects the carrier injection in the active region as the electrons and holes are captured by sidewall defects. These effects are more dominant at low current density in μLED while at high current density, the sidewall defects get saturated, and the surface recombination weakens. Various optimization strategies, such as quantum wells (QWs) width, quantum barriers (QBs) width, and QW number are carried out to study the effect on the performance of 25 × 25 μm<sup>2</sup> UV-C μLED. These optimization strategies at low current density (0.1 A/cm<sup>2</sup>) further improved the electrical/optical properties of AlGaN-based UV-C μLEDs.</div></div>","PeriodicalId":16159,"journal":{"name":"Journal of Luminescence","volume":"277 ","pages":"Article 120951"},"PeriodicalIF":3.3,"publicationDate":"2024-10-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142540278","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Owing to inherent structural instability of perovskite quantum dots, they are instability in humid environments and high temperatures conditions. To address this issue, a simple, environmentally friendly glass encapsulated technology is used to protect the perovskite quantum dots. Meanwhile, the dual-phase perovskite structure realized by phase transition engineering can further increase the stability of perovskite quantum dots. In this study, 3D CsPbBr3/0D Cs4PbBr6 dual-phase coexisting perovskite quantum dot glass powders were synthesized through melt quenching and subsequent crystallization induction of thermal treatment and water molecule, respectively. Results showed that compared with thermal treatment induction, perovskite QDs glass powders by water molecules induction exhibited a high PLQY of 24.7 % with a central wavelength of 519 nm and displayed excellent environmental stability. By combining green fluorescence from 3D CsPbBr3/0D Cs4PbBr6 QDs glass powders and red fluorescence powders (CaAlSiN3:Eu), a WLED device with an impressive EQE of 20.6 % was created, indicating a promising application potential.
{"title":"Dual-phase Cs4PbBr6/CsPbBr3 perovskite quantum dot borosilicate glass for WLED applications","authors":"Zhigang Yang, Shuqin Zhang, Junshuai Chen, Tianqing Sheng, Xinran Lv, Xuguang Wei, Guoqiang Qin, Gang Yu","doi":"10.1016/j.jlumin.2024.120953","DOIUrl":"10.1016/j.jlumin.2024.120953","url":null,"abstract":"<div><div>Owing to inherent structural instability of perovskite quantum dots, they are instability in humid environments and high temperatures conditions. To address this issue, a simple, environmentally friendly glass encapsulated technology is used to protect the perovskite quantum dots. Meanwhile, the dual-phase perovskite structure realized by phase transition engineering can further increase the stability of perovskite quantum dots. In this study, 3D CsPbBr<sub>3</sub>/0D Cs<sub>4</sub>PbBr<sub>6</sub> dual-phase coexisting perovskite quantum dot glass powders were synthesized through melt quenching and subsequent crystallization induction of thermal treatment and water molecule, respectively. Results showed that compared with thermal treatment induction, perovskite QDs glass powders by water molecules induction exhibited a high PLQY of 24.7 % with a central wavelength of 519 nm and displayed excellent environmental stability. By combining green fluorescence from 3D CsPbBr<sub>3</sub>/0D Cs<sub>4</sub>PbBr<sub>6</sub> QDs glass powders and red fluorescence powders (CaAlSiN<sub>3</sub>:Eu), a WLED device with an impressive EQE of 20.6 % was created, indicating a promising application potential.</div></div>","PeriodicalId":16159,"journal":{"name":"Journal of Luminescence","volume":"277 ","pages":"Article 120953"},"PeriodicalIF":3.3,"publicationDate":"2024-10-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142540279","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-22DOI: 10.1016/j.jlumin.2024.120955
B.U. Mendoza Enriquez , Miriam Rangel , Y. Kumar , S. Khandual , V. Agarwal
Nanomaterials with multicolor emission have been of great interest due to their versatility. Recently, environmentally friendly carbon dots (CDs) with excitation wavelength/solvent/dopant dependent emission have been used for designing different types of white light emitting diodes (W-LED). In this work, single-green precursor (Arthrospira platensis) derived CDs from a one-step hydro/solvothermal synthesis, have been implemented in the elaboration of W-LEDs. The white emission of CDs was modulated by the solvent engineering and doping strategies. A CDs/PVA composite based W-LED with a color render index (CRI) upper to ∼90 %, Commission Internationale Eclairage (CIE) coordinates of (0.31, 0.33) and correlated color temperature (CCT) of 6500 K is demonstrated. These findings suggest that white CDs derived from A. platensis possess promising potential in the field of optoelectronic devices, especially in the production of efficient and high-quality white illumination.
{"title":"Algae derived carbon dots and its polymeric composites for white light emission","authors":"B.U. Mendoza Enriquez , Miriam Rangel , Y. Kumar , S. Khandual , V. Agarwal","doi":"10.1016/j.jlumin.2024.120955","DOIUrl":"10.1016/j.jlumin.2024.120955","url":null,"abstract":"<div><div>Nanomaterials with multicolor emission have been of great interest due to their versatility. Recently, environmentally friendly carbon dots (CDs) with excitation wavelength/solvent/dopant dependent emission have been used for designing different types of white light emitting diodes (W-LED). In this work, single-green precursor (<em>Arthrospira platensis</em>) derived CDs from a one-step hydro/solvothermal synthesis, have been implemented in the elaboration of W-LEDs. The white emission of CDs was modulated by the solvent engineering and doping strategies. A CDs/PVA composite based W-LED with a color render index (CRI) upper to ∼90 %, Commission Internationale Eclairage (CIE) coordinates of (0.31, 0.33) and correlated color temperature (CCT) of <span><math><mrow><mo>∼</mo></mrow></math></span> 6500 K is demonstrated. These findings suggest that white CDs derived from <em>A. platensis</em> possess promising potential in the field of optoelectronic devices, especially in the production of efficient and high-quality white illumination.</div></div>","PeriodicalId":16159,"journal":{"name":"Journal of Luminescence","volume":"277 ","pages":"Article 120955"},"PeriodicalIF":3.3,"publicationDate":"2024-10-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142587208","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-22DOI: 10.1016/j.jlumin.2024.120949
Siyu Hou , Baowen Wang , Yan Zhang , Hui Chang , Xingqiang Lü , Guorui Fu , Hongyang Zhang
Despite the great success of Ir(III)-complex-based green/red-light OLEDs (OLED = organic light-emitting diode), the realization of their efficient blue-OLEDs is far behind and challenging. Herein, using HdFppy (2-(2,4-difluorophenyl)pyridine) and CN-ppzH (4-(1H-pyrazol-1-yl)benzonitrile) as the HC^N/HC’^N’ ligands and Hpic (2-picolinic acid) as the N’’^O-ancillary ligand, the [Ir(C^N)(C’^N’)(N’’^O)]-tris-heteroleptic molecular design strategy was adopted, obtaining the two [Ir(dFppy)(CN-ppz)(pic)]-configured blue-emitting (λPL (photoluminescence emission peak) = 466, 496(sh) nm; ΦPL (photoluminescence quantum efficiency) = 0.41–0.46) geometrical isomers 1a and 1b. Further through the doped and vacuum-deposited fabrication, their blue-OLEDs-1A/1B with the LMax (maximum luminance) values up to 18090–22528 cd/m2 and the ηEQEMax (maximum external quantum efficiency) sizes of 7.99–8.42 %, were realized, respectively. This study result shows that [Ir(dFppy)(CN-ppz)(pic)]-included [Ir(C^N)(C’^N’)(N’’^O)]-tris-heteroleptic Ir(III)-complexes can be used as the attractive blue-phosphor candidates forwards to efficient blue-OLEDs.
{"title":"Geometrically isomeric [Ir(C^N)(C’^N’)(N’’^O)-tris-heteroleptic [Ir(dFppy)(CN-ppz)(pic)] Ir(III)-complexes with blue-light: Forwards to efficient blue organic light-emitting diodes","authors":"Siyu Hou , Baowen Wang , Yan Zhang , Hui Chang , Xingqiang Lü , Guorui Fu , Hongyang Zhang","doi":"10.1016/j.jlumin.2024.120949","DOIUrl":"10.1016/j.jlumin.2024.120949","url":null,"abstract":"<div><div>Despite the great success of Ir(III)-complex-based green/red-light OLEDs (OLED = organic light-emitting diode), the realization of their efficient blue-OLEDs is far behind and challenging. Herein, using <strong>HdFppy</strong> (2-(2,4-difluorophenyl)pyridine) and <strong>CN-ppzH</strong> (4-(1<em>H</em>-pyrazol-1-yl)benzonitrile) as the HC^N/HC’^N’ ligands and <strong>Hpic</strong> (2-picolinic acid) as the N’’^O-ancillary ligand, the [Ir(C^N)(C’^N’)(N’’^O)]-<em>tris</em>-heteroleptic molecular design strategy was adopted, obtaining the two [Ir(dFppy)(CN-ppz)(pic)]-configured blue-emitting (<em>λ</em><sub>PL</sub> (photoluminescence emission peak) = 466, 496(sh) nm; <em>Φ</em><sub>PL</sub> (photoluminescence quantum efficiency) = 0.41–0.46) geometrical isomers <strong>1a</strong> and <strong>1b</strong>. Further through the doped and vacuum-deposited fabrication, their <strong>blue-OLEDs-1A/1B</strong> with the <em>L</em><sup>Max</sup> (maximum luminance) values up to 18090–22528 cd/m<sup>2</sup> and the <em>η</em><sub>EQE</sub><sup>Max</sup> (maximum external quantum efficiency) sizes of 7.99–8.42 %, were realized, respectively. This study result shows that [Ir(dFppy)(CN-ppz)(pic)]-included [Ir(C^N)(C’^N’)(N’’^O)]-<em>tris</em>-heteroleptic Ir(III)-complexes can be used as the attractive blue-phosphor candidates forwards to efficient blue-OLEDs.</div></div>","PeriodicalId":16159,"journal":{"name":"Journal of Luminescence","volume":"277 ","pages":"Article 120949"},"PeriodicalIF":3.3,"publicationDate":"2024-10-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142540280","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
One of the best rare earth combinations for down- and up-converting the solar photons is Er3+/Yb3+. Therefore, at present, by using the traditional melt quench technique, zinc tellurite glasses doped with Er3+ and Er3+/Yb3+ were characterised. Several methods of down-conversion that result in the emission of 1000 nm from the acceptor (Yb3+) under excitation of donor (Er3+) were studied. On the other hand, the impact of acceptor (Yb3+) concentration and excitation pump power on the excited state absorption and its influence on the up-conversion emission (1000 nm) properties were investigated in detail under 1535 nm excitation. The studies on emission and decay results are discovered to be very significant. Suggesting that these glasses when used as conversion layers, can append the conversion efficiency of Si-based solar cells.
{"title":"Stokes and anti-Stokes emission characteristics of Er3+/Yb3+ co-doped zinc tellurite glasses under 377 and 1550 nm excitations for solar energy conversion application","authors":"Keenatampalle Suresh , C.R. Kesavulu , C.J. Deviprasad , Wisanu Pecharapa , Upendra Kumar Kagola , Th Tröster , C.K. Jayasankar","doi":"10.1016/j.jlumin.2024.120948","DOIUrl":"10.1016/j.jlumin.2024.120948","url":null,"abstract":"<div><div>One of the best rare earth combinations for down- and up-converting the solar photons is Er<sup>3+</sup>/Yb<sup>3+</sup>. Therefore, at present, by using the traditional melt quench technique, zinc tellurite glasses doped with Er<sup>3+</sup> and Er<sup>3+</sup>/Yb<sup>3+</sup> were characterised. Several methods of down-conversion that result in the emission of 1000 nm from the acceptor (Yb<sup>3+</sup>) under excitation of donor (Er<sup>3+</sup>) were studied. On the other hand, the impact of acceptor (Yb<sup>3+</sup>) concentration and excitation pump power on the excited state absorption and its influence on the up-conversion emission (1000 nm) properties were investigated in detail under 1535 nm excitation. The studies on emission and decay results are discovered to be very significant. Suggesting that these glasses when used as conversion layers, can append the conversion efficiency of Si-based solar cells.</div></div>","PeriodicalId":16159,"journal":{"name":"Journal of Luminescence","volume":"277 ","pages":"Article 120948"},"PeriodicalIF":3.3,"publicationDate":"2024-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142540372","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Herein, rice straw-based biochar was intercalated with Co/Al-LDH (LDH-Biochar) using a green technique based on the co-precipitation method. LDH-Biochar was further evaluated for the naked eye detection and spectrofluorimetric analysis of dibutyl phosphate (DBP), diphenyl phosphate (DPP), and diethyl chlorophosphate (DCP), which are extensively used as pesticides and flame retardants. The material inherited a fluorescent signal with a maximum at 570 nm (λexc = 520 nm) from the precursor ‘biochar’ and porous interactive surface from the precursor ‘LDH.’ It showed selective quenching for the organophosphates, i.e., DBP, DPP, and DCP, with a detection limit of 1.39 μM, 1.17 μM, and 1.29 μM, respectively, and the probe showed good response within the linear range of 1.9–25.3 μM. Furthermore, the method was successfully implemented to extract the organophosphates from wheat, corn, and pearl millet with recoveries in the range of 97.49–101.35 % (RSD; 0.27–3.22 %), 97.08–99.91 % (RSD; 0.27–3.17 %), and 98.18–103.54 % (RSD; 0.19–4.76 %), respectively. The outcome of this research is thus expected to help develop LDH-Biochar as a multi-analyte sensor for organophosphates (DBP, DPP, and DCP), which are extensively used as pesticides and flame retardants.
{"title":"Cobalt/Aluminum layered double hydroxide intercalated with rice straw based-biochar for recognizing organophosphates in cereal crops","authors":"Harshita Gupta , Kulwinder Kaur , Irshad Mohiuddin , Raghubir Singh , Varinder Kaur","doi":"10.1016/j.jlumin.2024.120950","DOIUrl":"10.1016/j.jlumin.2024.120950","url":null,"abstract":"<div><div>Herein, rice straw-based biochar was intercalated with Co/Al-LDH (LDH-Biochar) using a green technique based on the co-precipitation method. LDH-Biochar was further evaluated for the naked eye detection and spectrofluorimetric analysis of dibutyl phosphate (DBP), diphenyl phosphate (DPP), and diethyl chlorophosphate (DCP), which are extensively used as pesticides and flame retardants. The material inherited a fluorescent signal with a maximum at 570 nm (λ<sub>exc</sub> = 520 nm) from the precursor ‘biochar’ and porous interactive surface from the precursor ‘LDH.’ It showed selective quenching for the organophosphates, i.e., DBP, DPP, and DCP, with a detection limit of 1.39 μM, 1.17 μM, and 1.29 μM, respectively, and the probe showed good response within the linear range of 1.9–25.3 μM. Furthermore, the method was successfully implemented to extract the organophosphates from wheat, corn, and pearl millet with recoveries in the range of 97.49–101.35 % (RSD; 0.27–3.22 %), 97.08–99.91 % (RSD; 0.27–3.17 %), and 98.18–103.54 % (RSD; 0.19–4.76 %), respectively. The outcome of this research is thus expected to help develop LDH-Biochar as a multi-analyte sensor for organophosphates (DBP, DPP, and DCP), which are extensively used as pesticides and flame retardants.</div></div>","PeriodicalId":16159,"journal":{"name":"Journal of Luminescence","volume":"277 ","pages":"Article 120950"},"PeriodicalIF":3.3,"publicationDate":"2024-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142540277","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
- Light-emitting diode (LED) has become the most popular lighting device in the world, but the harm of blue light brought by LEDs still remains a very important problem. The natural bamboo possesses a unique hierarchical structure and can be treated as an optical management material applied in the photoelectric device after the treatment of lignin removal or lignin modification. In this paper, we have discovered that the blue light hazards of white LEDs can be effectively suppressed after introducing the transparent bamboo (TB) based on above treatment. Five types of white LEDs are adopted for performing this study, and more than 27 % decrease of blue light hazard efficiency can be found after covering the TB processed by lignin modification and polymer impregnation, although more or less optical loss happens. This fact may be attributed to different light scattering effects of TB in the blue band and others in the visible range. After that, the circadian effects of two types of white LEDs (warm white and neutral white) while the TB is covered on them are also discussed. This work provides an effective method for suppressing blue light hazards, regulating circadian effects, and maintaining the color performance of LED lighting as much as possible.
- 发光二极管（LED）已成为世界上最流行的照明设备，但 LED 带来的蓝光危害仍是一个非常重要的问题。天然竹子具有独特的层次结构，经过木质素去除或木质素改性处理后，可作为光电管理材料应用于光电器件中。本文发现，在上述处理的基础上，引入透明竹材（TB）后，可有效抑制白光 LED 的蓝光危害。本研究采用了五种类型的白光 LED，发现在覆盖经过木质素改性和聚合物浸渍处理的透明竹材后，蓝光危害效率降低了 27%以上，但或多或少会出现光学损失。这可能是由于 TB 在蓝光波段和其他可见光波段的光散射效应不同所致。随后，还讨论了在两种白光 LED（暖白光和中性白光）上覆盖 TB 时的昼夜效应。这项研究为抑制蓝光危害、调节昼夜节律效应和尽可能保持 LED 照明的色彩性能提供了一种有效的方法。
{"title":"A novel strategy for suppressing blue light hazards of white light-emitting diodes by using transparent bamboo","authors":"Yaling Chai , Xiaorong Yin , Ziquan Guo , Zhong Chen , Caichao Wan","doi":"10.1016/j.jlumin.2024.120942","DOIUrl":"10.1016/j.jlumin.2024.120942","url":null,"abstract":"<div><div>- Light-emitting diode (LED) has become the most popular lighting device in the world, but the harm of blue light brought by LEDs still remains a very important problem. The natural bamboo possesses a unique hierarchical structure and can be treated as an optical management material applied in the photoelectric device after the treatment of lignin removal or lignin modification. In this paper, we have discovered that the blue light hazards of white LEDs can be effectively suppressed after introducing the transparent bamboo (TB) based on above treatment. Five types of white LEDs are adopted for performing this study, and more than 27 % decrease of blue light hazard efficiency can be found after covering the TB processed by lignin modification and polymer impregnation, although more or less optical loss happens. This fact may be attributed to different light scattering effects of TB in the blue band and others in the visible range. After that, the circadian effects of two types of white LEDs (warm white and neutral white) while the TB is covered on them are also discussed. This work provides an effective method for suppressing blue light hazards, regulating circadian effects, and maintaining the color performance of LED lighting as much as possible.</div></div>","PeriodicalId":16159,"journal":{"name":"Journal of Luminescence","volume":"277 ","pages":"Article 120942"},"PeriodicalIF":3.3,"publicationDate":"2024-10-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142540275","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-16DOI: 10.1016/j.jlumin.2024.120943
Iu. Nasieka , V. Strel'nitskij , O. Opalev , V. Gritsina , K. Koshevyi , O. Horobei , M. Zablodskyi , V. Lozinskii , V. Temchenko
The changes in the shape of micro-photoluminescence spectra of PECVD diamond micro-crystal measured, depending on the position of the excitation laser spot along the crystallite height, were analyzed. It was ascertained that the processes of SiV defect formation non-monotonically depend on the distance from the Si substrate. At the distances of 2–20 μm the concentration of SiV defects increases, then at distances larger than 20 μm the number of SiV defects decreases. The concentration of NV− and NV0 defects monotonically increases with the distance from the Si substrate. The predomination of SiV defect formation at the beginning stages of the crystal growth is explained by the substantial concentration of carbon vacancies required for their formation. With the increase in the distance from the substrate, the crystalline perfection increases, the concentration of carbon vacancies decreases and the processes of NV− and NV0 defect formation dominate. The increase in CH4 fraction within 0.75–6 % leads to the increase in the volume fraction of graphite-like carbon, which is the good diffusion channel for Si atoms from the substrate into the plasma. Therefore, the concentration of SiV, NV−, and NV0 defects on the surface of the crystal depends on the volume fraction of graphite-like carbon defined by CH4 content.
{"title":"The evolution of micro-photoluminescence spectra of PECVD diamond microcrystals along the vertical growth direction and their dependence on CH4 concentration","authors":"Iu. Nasieka , V. Strel'nitskij , O. Opalev , V. Gritsina , K. Koshevyi , O. Horobei , M. Zablodskyi , V. Lozinskii , V. Temchenko","doi":"10.1016/j.jlumin.2024.120943","DOIUrl":"10.1016/j.jlumin.2024.120943","url":null,"abstract":"<div><div>The changes in the shape of micro-photoluminescence spectra of PECVD diamond micro-crystal measured, depending on the position of the excitation laser spot along the crystallite height, were analyzed. It was ascertained that the processes of SiV defect formation non-monotonically depend on the distance from the Si substrate. At the distances of 2–20 μm the concentration of SiV defects increases, then at distances larger than 20 μm the number of SiV defects decreases. The concentration of NV<sup>−</sup> and NV<sup>0</sup> defects monotonically increases with the distance from the Si substrate. The predomination of SiV defect formation at the beginning stages of the crystal growth is explained by the substantial concentration of carbon vacancies required for their formation. With the increase in the distance from the substrate, the crystalline perfection increases, the concentration of carbon vacancies decreases and the processes of NV<sup>−</sup> and NV<sup>0</sup> defect formation dominate. The increase in CH<sub>4</sub> fraction within 0.75–6 % leads to the increase in the volume fraction of graphite-like carbon, which is the good diffusion channel for Si atoms from the substrate into the plasma. Therefore, the concentration of SiV, NV<sup>−</sup>, and NV<sup>0</sup> defects on the surface of the crystal depends on the volume fraction of graphite-like carbon defined by CH<sub>4</sub> content.</div></div>","PeriodicalId":16159,"journal":{"name":"Journal of Luminescence","volume":"277 ","pages":"Article 120943"},"PeriodicalIF":3.3,"publicationDate":"2024-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142446101","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-16DOI: 10.1016/j.jlumin.2024.120945
V. Babin , P. Bohacek , A. Krasnikov , M. Nikl , L. Vasylechko , S. Zazubovich
Heavily doped single crystals of Gd3GaxAl5-xO12:Ce, Mg (x = 2.46–2.95) with different concentrations of Ce (0.016–0.188 at.%) and Mg (0–0.083 at.%) are investigated by the X-ray diffraction, photoluminescence, and thermoluminescence methods. Dependences of the luminescence characteristics, as well as crystal lattice parameters and distances between the Ce3+ and Mg2+ ions, on the Ga, Ce, and Mg concentration are studied. Mechanisms of the processes, resulting in the photoluminescence optical and thermal quenching and acceleration of decay kinetics, and the influence of the crystal composition on these processes are discussed. The role of close {Ce3+ - Mg2+Ga} pairs in these processes is considered. At T > 400 K, the luminescence thermal quenching is caused by the crossover process, while in the 200–350 K temperature range, by the electron transfer from the 5d1 excited state of Ce3+ to nearby defect levels (electron traps) located between the 5d1 level and the conduction band. The latter process results also in the appearance of thermally stimulated luminescence, and its efficiency depends on the Ga3+ content and concentration of intrinsic defects. The optimum concentrations of Ga3+ and Mg2+ ions in the investigated crystals are determined.
通过 X 射线衍射、光致发光和热致发光方法研究了不同浓度的 Ce（0.016-0.188%）和 Mg（0-0.083%）的 Gd3GaxAl5-xO12:Ce, Mg（x = 2.46-2.95）重掺杂单晶。研究了发光特性、晶格参数以及 Ce3+ 和 Mg2+ 离子之间的距离对 Ga、Ce 和 Mg 浓度的影响。讨论了导致光致发光光学和热淬灭以及衰变动力学加速的过程机理，以及晶体成分对这些过程的影响。研究还考虑了近距离{Ce3+ - Mg2+Ga}对在这些过程中的作用。在 T > 400 K 时，发光热淬灭是由交叉过程引起的，而在 200-350 K 温度范围内，则是由电子从 Ce3+ 的 5d1 激发态转移到位于 5d1 电平和导带之间的附近缺陷电平（电子陷阱）引起的。后一过程也会导致热刺激发光的出现，其效率取决于 Ga3+ 的含量和固有缺陷的浓度。研究确定了所研究晶体中 Ga3+ 和 Mg2+ 离子的最佳浓度。
{"title":"Photoluminescence optical and thermal quenching in heavily doped Gd3(Ga,Al)5O12:Ce, Mg single crystals: Dependence on the Ga3+, Ce3+, and Mg2+ concentration","authors":"V. Babin , P. Bohacek , A. Krasnikov , M. Nikl , L. Vasylechko , S. Zazubovich","doi":"10.1016/j.jlumin.2024.120945","DOIUrl":"10.1016/j.jlumin.2024.120945","url":null,"abstract":"<div><div>Heavily doped single crystals of Gd<sub>3</sub>Ga<sub>x</sub>Al<sub>5-x</sub>O<sub>12</sub>:Ce, Mg (x = 2.46–2.95) with different concentrations of Ce (0.016–0.188 at.%) and Mg (0–0.083 at.%) are investigated by the X-ray diffraction, photoluminescence, and thermoluminescence methods. Dependences of the luminescence characteristics, as well as crystal lattice parameters and distances between the Ce<sup>3+</sup> and Mg<sup>2+</sup> ions, on the Ga, Ce, and Mg concentration are studied. Mechanisms of the processes, resulting in the photoluminescence optical and thermal quenching and acceleration of decay kinetics, and the influence of the crystal composition on these processes are discussed. The role of close {Ce<sup>3+</sup> - Mg<sup>2+</sup><sub>Ga</sub>} pairs in these processes is considered. At <em>T</em> > 400 K, the luminescence thermal quenching is caused by the crossover process, while in the 200–350 K temperature range, by the electron transfer from the 5d<sub>1</sub> excited state of Ce<sup>3+</sup> to nearby defect levels (electron traps) located between the 5d<sub>1</sub> level and the conduction band. The latter process results also in the appearance of thermally stimulated luminescence, and its efficiency depends on the Ga<sup>3+</sup> content and concentration of intrinsic defects. The optimum concentrations of Ga<sup>3+</sup> and Mg<sup>2+</sup> ions in the investigated crystals are determined.</div></div>","PeriodicalId":16159,"journal":{"name":"Journal of Luminescence","volume":"277 ","pages":"Article 120945"},"PeriodicalIF":3.3,"publicationDate":"2024-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142446100","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-16DOI: 10.1016/j.jlumin.2024.120946
Lihua Ye, Shaoqiang Hong, Chunguang Lu, Qing Zhao
In recent years, metal halide perovskite has gradually become a hotspot in the field of optoelectronics. However, the inherent instability of CsPbX3 quantum dots (QDs) seriously affects the amplified spontaneous emission (ASE) or lasing performance. Herein, the highly stable CsPbBr3 random laser is realized in SiO2-QDs-SiO2 (SQS) composite nanostructure doped with Ag nanoislands. The strong scattering generated by SQS composite nanostructure and the localized surface plasmon resonance (LSPR) of metal silver nanoislands provide optical feedback for the formation of random laser. Then a coherent random laser with low threshold (∼2.2 mJ/cm2) is obtained. SiO2 microspheres anchor QDs to avoid photoinduced regeneration and fluorescence quenching caused by QDs clusters. The inner QDs of SQS are effectively protected from water erosion, thus resulting that the samples have higher water resistance. The luminescence intensity still maintains 70 % of the original intensity after 40 days with the addition of pure water. Our research provides an effective method for improving the water stability of perovskite QDs. The highly stable random laser based on perovskite quantum dot film has a wide application prospect in integrated optoelectronics, display imaging and sensing measurement.
{"title":"Stable random laser of perovskite quantum dots based on SiO2-QDs-SiO2 composite nanostructure","authors":"Lihua Ye, Shaoqiang Hong, Chunguang Lu, Qing Zhao","doi":"10.1016/j.jlumin.2024.120946","DOIUrl":"10.1016/j.jlumin.2024.120946","url":null,"abstract":"<div><div>In recent years, metal halide perovskite has gradually become a hotspot in the field of optoelectronics. However, the inherent instability of CsPbX<sub>3</sub> quantum dots (QDs) seriously affects the amplified spontaneous emission (ASE) or lasing performance. Herein, the highly stable CsPbBr<sub>3</sub> random laser is realized in SiO<sub>2</sub>-QDs-SiO<sub>2</sub> (SQS) composite nanostructure doped with Ag nanoislands. The strong scattering generated by SQS composite nanostructure and the localized surface plasmon resonance (LSPR) of metal silver nanoislands provide optical feedback for the formation of random laser. Then a coherent random laser with low threshold (∼2.2 mJ/cm<sup>2</sup>) is obtained. SiO<sub>2</sub> microspheres anchor QDs to avoid photoinduced regeneration and fluorescence quenching caused by QDs clusters. The inner QDs of SQS are effectively protected from water erosion, thus resulting that the samples have higher water resistance. The luminescence intensity still maintains 70 % of the original intensity after 40 days with the addition of pure water. Our research provides an effective method for improving the water stability of perovskite QDs. The highly stable random laser based on perovskite quantum dot film has a wide application prospect in integrated optoelectronics, display imaging and sensing measurement.</div></div>","PeriodicalId":16159,"journal":{"name":"Journal of Luminescence","volume":"277 ","pages":"Article 120946"},"PeriodicalIF":3.3,"publicationDate":"2024-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142446102","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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