Pub Date : 2023-09-05DOI: 10.1007/s13391-023-00456-x
Jong Seok Chung, Eung Soo Kim
Microwave dielectric properties of MgTi1-x(Mn1/3Nb2/3)xO3 (0 ≤ x ≤ 0.05) ceramics were investigated based on their crystal structure characteristics. For the specimens sintered at 1400 °C for 4 h, complete solid solutions with a single phase and an ilmenite structure were obtained for the entire range of compositions. The quality factor (Qf) was dependent on the average Ti-site covalency related to the electronegativity difference and the reduction state of Ti4+. MgTi0.995(Mn1/3Nb2/3)0.005O3 exhibited the highest Qf value of 212,000 GHz owing to the high average covalency obtained from the Rietveld refinement of X-ray Diffraction patterns, high binding energy, and small full width at half maximum of Ti 2p peaks, as confirmed by X-ray Photoelectron Spectroscopy of MgTiO3 –based ceramics. The temperature coefficients of the resonant frequency (TCF) of MgTiO3-based ceramics were dependent on the degree of average oxygen octahedral distortion of the ilmenite structure. The dielectric constant (K) was affected by the theoretical dielectric polarizability of the constituent ions of sintered specimens. Excellent microwave dielectric properties were obtained for MgTi0.995(Mn1/3Nb2/3)0.005O3; K = 18.05, Qf = 212,000 GHz, TCF = − 37.04 ppm/°C. The microwave dielectric properties were improved by substituting (Mn1/3Nb2/3)4+ for Ti4+ in MgTiO3-based ceramics.
Graphical Abstract
根据 MgTi1-x(Mn1/3Nb2/3)xO3（0 ≤ x ≤ 0.05）陶瓷的晶体结构特征，研究了其微波介电性能。对于在 1400 °C 下烧结 4 小时的试样，在整个成分范围内都获得了具有单相和钛铁矿结构的完整固溶体。品质因数（Qf）取决于与电负性差异和 Ti4+ 的还原状态有关的平均 Ti 位共价。MgTi0.995(Mn1/3Nb2/3)0.005O3 的 Qf 值最高，达到 212,000 GHz，这是因为根据 X 射线衍射图样的里特维尔德细化得到的平均共价率高、结合能高、Ti 2p 峰的半最大全宽小，这一点已通过 MgTiO3 基陶瓷的 X 射线光电子能谱分析得到证实。MgTiO3 基陶瓷的共振频率温度系数（TCF）取决于钛铁矿结构的八面体平均氧畸变程度。介电常数（K）受烧结试样中组成离子的理论介电极化率的影响。MgTi0.995(Mn1/3Nb2/3)0.005O3 获得了优异的微波介电性能；K = 18.05，Qf = 212,000 GHz，TCF = - 37.04 ppm/°C。通过在 MgTiO3 基陶瓷中用 (Mn1/3Nb2/3)4+ 代替 Ti4+，微波介电性能得到了改善。 图文摘要
{"title":"Improvement of Microwave Dielectric Properties of MgTiO3 Ceramics by Ti-Site Complex Substitution","authors":"Jong Seok Chung, Eung Soo Kim","doi":"10.1007/s13391-023-00456-x","DOIUrl":"10.1007/s13391-023-00456-x","url":null,"abstract":"<div><p>Microwave dielectric properties of MgTi<sub>1-<i>x</i></sub>(Mn<sub>1/3</sub>Nb<sub>2/3</sub>)<sub><i>x</i></sub>O<sub>3</sub> (0 ≤ <i>x</i> ≤ 0.05) ceramics were investigated based on their crystal structure characteristics. For the specimens sintered at 1400 °C for 4 h, complete solid solutions with a single phase and an ilmenite structure were obtained for the entire range of compositions. The quality factor (<i>Qf</i>) was dependent on the average Ti-site covalency related to the electronegativity difference and the reduction state of Ti<sup>4+</sup>. MgTi<sub>0.995</sub>(Mn<sub>1/3</sub>Nb<sub>2/3</sub>)<sub>0.005</sub>O<sub>3</sub> exhibited the highest <i>Qf</i> value of 212,000 GHz owing to the high average covalency obtained from the Rietveld refinement of X-ray Diffraction patterns, high binding energy, and small full width at half maximum of Ti 2<i>p</i> peaks, as confirmed by X-ray Photoelectron Spectroscopy of MgTiO<sub>3</sub> –based ceramics. The temperature coefficients of the resonant frequency (<i>TCF</i>) of MgTiO<sub>3</sub>-based ceramics were dependent on the degree of average oxygen octahedral distortion of the ilmenite structure. The dielectric constant (<i>K</i>) was affected by the theoretical dielectric polarizability of the constituent ions of sintered specimens. Excellent microwave dielectric properties were obtained for MgTi<sub>0.995</sub>(Mn<sub>1/3</sub>Nb<sub>2/3</sub>)<sub>0.005</sub>O<sub>3</sub>; <i>K</i> = 18.05, <i>Qf</i> = 212,000 GHz, TCF = − 37.04 ppm/°C. The microwave dielectric properties were improved by substituting (Mn<sub>1/3</sub>Nb<sub>2/3</sub>)<sup>4+</sup> for Ti<sup>4+</sup> in MgTiO<sub>3</sub>-based ceramics.</p><h3>Graphical Abstract</h3>\u0000<div><figure><div><div><picture><source><img></source></picture></div></div></figure></div></div>","PeriodicalId":536,"journal":{"name":"Electronic Materials Letters","volume":"20 1","pages":"56 - 64"},"PeriodicalIF":2.1,"publicationDate":"2023-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44908522","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-09-01DOI: 10.1007/s13391-023-00454-z
Yaoyang Hu, Geoffrey Rivers, Michael P. Weir, David B. Amabilino, Christopher J. Tuck, Ricky D. Wildman, Oleg Makarovsky, Simon Woodward
We describe the synthesis and characterisation of the first of a new class of soluble ladder oligomeric thermoelectric material based on previously unutilised ethene-1,1,2,2-tetrasulfonic acid. Reaction of Ba(OH)2 and propionic acid at a 1:1 stoichiometry leads to the formation of the previously unrecognised soluble [Ba(OH)(O2CEt)]⋅H2O. The latter when used to hydrolyse 1,3,4,6-tetrathiapentalene-2,5-dione (TPD), in the presence of NiCl2, forms a new material whose elemental composition is in accord with the formula [(EtCO2Ba)4Ni8{(O3S)2C = C(SO3)2}5]⋅22H2O (4). Compound 4 can be pressed into pellets, drop-cast as DMSO solutions or ink-jet printed (down to sub-mm resolutions). While its room temperature thermoelectric properties are modest (σmax 0.04 S cm−1 and Seebeck coefficient, αmax − 25.8 μV K−1) we introduce a versatile new oligomeric material that opens new possible synthetic routes for n-type thermoelectrics.
{"title":"A Soluble ‘Ba(Ni-ett)’ (ett = 1,1,2,2-Ethenetetrathiolate) Derived Thermoelectric Material","authors":"Yaoyang Hu, Geoffrey Rivers, Michael P. Weir, David B. Amabilino, Christopher J. Tuck, Ricky D. Wildman, Oleg Makarovsky, Simon Woodward","doi":"10.1007/s13391-023-00454-z","DOIUrl":"10.1007/s13391-023-00454-z","url":null,"abstract":"<div><p>We describe the synthesis and characterisation of the first of a new class of soluble ladder oligomeric thermoelectric material based on previously unutilised ethene-1,1,2,2-tetrasulfonic acid. Reaction of Ba(OH)<sub>2</sub> and propionic acid at a 1:1 stoichiometry leads to the formation of the previously unrecognised soluble [Ba(OH)(O<sub>2</sub>CEt)]⋅H<sub>2</sub>O. The latter when used to hydrolyse 1,3,4,6-tetrathiapentalene-2,5-dione (TPD), in the presence of NiCl<sub>2</sub>, forms a new material whose elemental composition is in accord with the formula [(EtCO<sub>2</sub>Ba)<sub>4</sub>Ni<sub>8</sub>{(O<sub>3</sub>S)<sub>2</sub>C = C(SO<sub>3</sub>)<sub>2</sub>}<sub>5</sub>]⋅22H<sub>2</sub>O (<b>4</b>). Compound <b>4</b> can be pressed into pellets, drop-cast as DMSO solutions or ink-jet printed (down to sub-mm resolutions). While its room temperature thermoelectric properties are modest (σ<sub>max</sub> 0.04 S cm<sup>−1</sup> and Seebeck coefficient, α<sub>max</sub> − 25.8 μV K<sup>−1</sup>) we introduce a versatile new oligomeric material that opens new possible synthetic routes for n-type thermoelectrics.</p><h3>Graphical Abstract</h3><div><figure><div><div><picture><source><img></source></picture></div></div></figure></div></div>","PeriodicalId":536,"journal":{"name":"Electronic Materials Letters","volume":"20 2","pages":"150 - 157"},"PeriodicalIF":2.1,"publicationDate":"2023-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s13391-023-00454-z.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48695533","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-08-28DOI: 10.1007/s13391-023-00455-y
Tae-Kyung Lee, Seung-Wook Kim, Dae-Yong Jeong
The demand for soft magnetic amorphous metal powders with high saturation magnetization values and low energy loss has increased to achieve high-performance inductors for mobile electronic devices. In this study, Fe-based Fe92.3Si3.5B3.0C0.7P0.5 (wt.%) amorphous metal powders were prepared using different atomization methods for controlling the surface oxidation of the metal alloy powder. Conventional high-pressure water atomization and the newly developed high-speed water screen atomization methods were used for preparation. Regardless of the preparation methods, both alloy powders were amorphous, and their magnetic flux density (Bs) values were more than 165 emu/g. Compared to the powders from the conventional high-pressure water atomization method, the amorphous metal powder manufactured using the high-speed water screen atomization process had lower eddy current loss because of the formation of a thin and uniform oxide layer. Furthermore, the magnetic properties of the consolidated magnetic cores fabricated with the amorphous powders produced by the high-speed water screen atomization method using compact-pressing techniques were characterized. Magnetic powders with fewer surface oxidation layers exhibited increased initial permeability and a smaller coercive field, leading to a lower core loss value. The magnetic core made from Fe92.3Si3.5B3.0C0.7P0.5 (wt.%) amorphous powder with an oxide content of 0.12 (wt.%) using the high-speed water screen atomization method exhibited an initial permeability of 25 in the frequency range up to 5 MHz, and a loss of 237 mW/cm3 with Bm = (0.2,{text{T}}) at 1 MHz.
{"title":"Effects of Surface Oxidation on the Magnetic Properties of Fe-Based Amorphous Metal Powder Made by Atomization Methods","authors":"Tae-Kyung Lee, Seung-Wook Kim, Dae-Yong Jeong","doi":"10.1007/s13391-023-00455-y","DOIUrl":"10.1007/s13391-023-00455-y","url":null,"abstract":"<div><p>The demand for soft magnetic amorphous metal powders with high saturation magnetization values and low energy loss has increased to achieve high-performance inductors for mobile electronic devices. In this study, Fe-based Fe<sub>92.3</sub>Si<sub>3.5</sub>B<sub>3.0</sub>C<sub>0.7</sub>P<sub>0.5</sub> (wt.%) amorphous metal powders were prepared using different atomization methods for controlling the surface oxidation of the metal alloy powder. Conventional high-pressure water atomization and the newly developed high-speed water screen atomization methods were used for preparation. Regardless of the preparation methods, both alloy powders were amorphous, and their magnetic flux density (<i>B</i>s) values were more than 165 emu/g. Compared to the powders from the conventional high-pressure water atomization method, the amorphous metal powder manufactured using the high-speed water screen atomization process had lower eddy current loss because of the formation of a thin and uniform oxide layer. Furthermore, the magnetic properties of the consolidated magnetic cores fabricated with the amorphous powders produced by the high-speed water screen atomization method using compact-pressing techniques were characterized. Magnetic powders with fewer surface oxidation layers exhibited increased initial permeability and a smaller coercive field, leading to a lower core loss value. The magnetic core made from Fe<sub>92.3</sub>Si<sub>3.5</sub>B<sub>3.0</sub>C<sub>0.7</sub>P<sub>0.5</sub> (wt.%) amorphous powder with an oxide content of 0.12 (wt.%) using the high-speed water screen atomization method exhibited an initial permeability of 25 in the frequency range up to 5 MHz, and a loss of 237 mW/cm<sup>3</sup> with <i>B</i><sub>m</sub> = <span>(0.2,{text{T}})</span> at 1 MHz.</p><h3>Graphical Abstract</h3>\u0000<div><figure><div><div><picture><source><img></source></picture></div></div></figure></div></div>","PeriodicalId":536,"journal":{"name":"Electronic Materials Letters","volume":"20 3","pages":"261 - 268"},"PeriodicalIF":2.1,"publicationDate":"2023-08-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42020855","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-08-27DOI: 10.1007/s13391-023-00451-2
Tae-Gyun Kwon, Younghoon Kim
Conductive paste inks have received considerable attention as facile conductive materials for the formation of electrode layers. However, conventional paste inks result in films with poor surface morphology. In addition, they require a high thermal annealing temperature for achieving high electrical conductivity because of their organic/inorganic composite structure, in which nanosized metal particles and polymeric organic binders are mixed in solvents. In this work, we prepare solvent-free and polymeric-binder-free metal nanoparticle (NP) fluids, which can be used as facile conductive pastes for forming an electrode layer after sintering at a considerably low temperature. We employ thiol-terminated imidazolium-type ionic liquid (IL-SH) molecules with a small molecular weight and fluidic behavior as the surface ligands of Ag NPs. IL-SH-stabilized Ag NPs exhibit fluidic behavior and metallic conducting properties at a considerably low sintering temperature of 250 °C.
{"title":"Conductive Paste Inks Prepared Using Ionic-Liquid-Stabilized Metal Nanoparticle Fluids and their Sintering Effect","authors":"Tae-Gyun Kwon, Younghoon Kim","doi":"10.1007/s13391-023-00451-2","DOIUrl":"10.1007/s13391-023-00451-2","url":null,"abstract":"<div><p>Conductive paste inks have received considerable attention as facile conductive materials for the formation of electrode layers. However, conventional paste inks result in films with poor surface morphology. In addition, they require a high thermal annealing temperature for achieving high electrical conductivity because of their organic/inorganic composite structure, in which nanosized metal particles and polymeric organic binders are mixed in solvents. In this work, we prepare solvent-free and polymeric-binder-free metal nanoparticle (NP) fluids, which can be used as facile conductive pastes for forming an electrode layer after sintering at a considerably low temperature. We employ thiol-terminated imidazolium-type ionic liquid (IL-SH) molecules with a small molecular weight and fluidic behavior as the surface ligands of Ag NPs. IL-SH-stabilized Ag NPs exhibit fluidic behavior and metallic conducting properties at a considerably low sintering temperature of 250 °C.</p><h3>Graphical Abstract</h3><div><figure><div><div><picture><source><img></source></picture></div></div></figure></div></div>","PeriodicalId":536,"journal":{"name":"Electronic Materials Letters","volume":"20 3","pages":"337 - 344"},"PeriodicalIF":2.1,"publicationDate":"2023-08-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44583471","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-08-24DOI: 10.1007/s13391-023-00453-0
Eunyeong Yang, Seoin Kang, Sanghyun Jeong, Kihyun Shin, Jung-Sub Wi, Joon Sik Park, Sangyeob Lee, Choong-Heui Chung
Mechanically flexible transparent conductive electrodes (TCEs) with high optoelectronic performance are essential for flexible or wearable optoelectronic devices, which are currently receiving a considerable amount of attention. In this study, we investigate the structural, electrical, optical and mechanical properties of electrodeposited hierarchical silver network TCEs consisting of two layers of silver nanowires (AgNWs) and a silver micromesh. Hierarchical structures are known to improve the optoelectronic properties of network-type TCEs. To fabricate an electrodeposited hierarchical network, a AgNW solution is first spun onto a substrate to form randomly distributed AgNWs, and a silver micromesh is then formed on the AgNWs. Subsequently, silver is electrodeposited onto the hierarchical network. As a result of the electrodeposition, AgNW-AgNW and AgNW-silver micromesh contacts are effectively welded, and the dimensions of the AgNWs and the silver micromesh are optimized to maximize the figure of merit of the TCE. Furthermore, the electrodeposited hierarchical silver network shows excellent mechanical flexibility and much less degradation of its sheet resistance than that experienced by ITO upon repeated convex and concave bending. Its resulting optoelectronic and mechanically flexible performance is superior to that of commercialized ITO.
{"title":"Electrodeposited Hierarchical Silver Network Transparent Conducting Electrodes with Excellent Optoelectronic Properties and Mechanical Flexibility","authors":"Eunyeong Yang, Seoin Kang, Sanghyun Jeong, Kihyun Shin, Jung-Sub Wi, Joon Sik Park, Sangyeob Lee, Choong-Heui Chung","doi":"10.1007/s13391-023-00453-0","DOIUrl":"10.1007/s13391-023-00453-0","url":null,"abstract":"<div><p>Mechanically flexible transparent conductive electrodes (TCEs) with high optoelectronic performance are essential for flexible or wearable optoelectronic devices, which are currently receiving a considerable amount of attention. In this study, we investigate the structural, electrical, optical and mechanical properties of electrodeposited hierarchical silver network TCEs consisting of two layers of silver nanowires (AgNWs) and a silver micromesh. Hierarchical structures are known to improve the optoelectronic properties of network-type TCEs. To fabricate an electrodeposited hierarchical network, a AgNW solution is first spun onto a substrate to form randomly distributed AgNWs, and a silver micromesh is then formed on the AgNWs. Subsequently, silver is electrodeposited onto the hierarchical network. As a result of the electrodeposition, AgNW-AgNW and AgNW-silver micromesh contacts are effectively welded, and the dimensions of the AgNWs and the silver micromesh are optimized to maximize the figure of merit of the TCE. Furthermore, the electrodeposited hierarchical silver network shows excellent mechanical flexibility and much less degradation of its sheet resistance than that experienced by ITO upon repeated convex and concave bending. Its resulting optoelectronic and mechanically flexible performance is superior to that of commercialized ITO.</p><h3>Graphical Abstract</h3>\u0000<div><figure><div><div><picture><source><img></source></picture></div></div></figure></div></div>","PeriodicalId":536,"journal":{"name":"Electronic Materials Letters","volume":"20 3","pages":"254 - 260"},"PeriodicalIF":2.1,"publicationDate":"2023-08-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"52846924","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-08-23DOI: 10.1007/s13391-023-00450-3
Ju Won Kim, Jin Gi An, Guen Hyung Oh, Joo Hyung Park, TaeWan Kim
Molybdenum disulfide (MoS2) grown via metal-organic chemical vapor deposition is known to exhibit high transparency and superior quality. Transparent thin-film transistor (TFT) based on a multilayer MoS2 film and indium zinc oxide (IZO) using a representative transparent conducting oxide as source and drain electrodes indicate more than 70% transmittance in the visible wavelength. However, the device performance is limited by the large Schottky barrier height corresponding to the high work function of IZO (~ 5.1 eV) and surface impurities generated during the wet transfer process and subsequent oxidation. In this study, we addressed this problem by employing air thermal annealing to improve the TFT device performance. Consequently, contact resistance is reduced ~ 10 times, and the field-effect mobility and on/off ratio measured using ion-gel side gate, which are important parameters for TFT device operation, were enhanced by ~ 59 and ~ 81 times, respectively.
{"title":"Improved Performance of Transparent MoS2 Thin-Film Transistor with IZO Electrodes by Air Thermal Annealing","authors":"Ju Won Kim, Jin Gi An, Guen Hyung Oh, Joo Hyung Park, TaeWan Kim","doi":"10.1007/s13391-023-00450-3","DOIUrl":"10.1007/s13391-023-00450-3","url":null,"abstract":"<div><p>Molybdenum disulfide (MoS<sub>2</sub>) grown via metal-organic chemical vapor deposition is known to exhibit high transparency and superior quality. Transparent thin-film transistor (TFT) based on a multilayer MoS<sub>2</sub> film and indium zinc oxide (IZO) using a representative transparent conducting oxide as source and drain electrodes indicate more than 70% transmittance in the visible wavelength. However, the device performance is limited by the large Schottky barrier height corresponding to the high work function of IZO (~ 5.1 eV) and surface impurities generated during the wet transfer process and subsequent oxidation. In this study, we addressed this problem by employing air thermal annealing to improve the TFT device performance. Consequently, contact resistance is reduced ~ 10 times, and the field-effect mobility and on/off ratio measured using ion-gel side gate, which are important parameters for TFT device operation, were enhanced by ~ 59 and ~ 81 times, respectively.</p><h3>Graphical abstract</h3>\u0000<div><figure><div><div><picture><source><img></source></picture></div></div></figure></div></div>","PeriodicalId":536,"journal":{"name":"Electronic Materials Letters","volume":"20 3","pages":"225 - 231"},"PeriodicalIF":2.1,"publicationDate":"2023-08-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47985145","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-08-23DOI: 10.1007/s13391-023-00452-1
Suk-Ho Song, Jae-In Yoo, Hyo-Bin Kim, Sung-Cheon Kang, Kanghoon Kim, Sung-Jae Park, Qun Yan, Jang-Kun Song
The efficiency improvement of organic light-emitting diodes (OLEDs) is important but challenging. Here, we introduce a unique OLED with a hole modulation layer (HML) in the middle of its emission layer (EML). The external quantum efficiency and power efficiency can be improved by approximately 58% when an HML with optimized thickness is inserted. HML insertion can efficiently retard hole flow, thus improving (i) exciton distribution uniformity and (ii) local electron–hole charge balance. A systematic study of the individual contributions of two EMLs separated by the HML shows that the former factor dominantly works at low current densities (< 10 mA/cm2), whereas the latter factor functions over the entire current density range of the OLED. Therefore, the efficiency improvement is greatest at low current densities, which aligns with the typical operating range in display applications. The results provide a deeper understanding of the OLED emission mechanism, and the proposed OLED structure can significantly benefit high-performance OLED displays.
{"title":"Manipulation of Hole and Exciton Distributions in Organic Light-Emitting Diodes with Dual Emission Layers","authors":"Suk-Ho Song, Jae-In Yoo, Hyo-Bin Kim, Sung-Cheon Kang, Kanghoon Kim, Sung-Jae Park, Qun Yan, Jang-Kun Song","doi":"10.1007/s13391-023-00452-1","DOIUrl":"10.1007/s13391-023-00452-1","url":null,"abstract":"<div><p>The efficiency improvement of organic light-emitting diodes (OLEDs) is important but challenging. Here, we introduce a unique OLED with a hole modulation layer (HML) in the middle of its emission layer (EML). The external quantum efficiency and power efficiency can be improved by approximately 58% when an HML with optimized thickness is inserted. HML insertion can efficiently retard hole flow, thus improving (<i>i</i>) exciton distribution uniformity and (<i>ii</i>) local electron–hole charge balance. A systematic study of the individual contributions of two EMLs separated by the HML shows that the former factor dominantly works at low current densities (< 10 mA/cm<sup>2</sup>), whereas the latter factor functions over the entire current density range of the OLED. Therefore, the efficiency improvement is greatest at low current densities, which aligns with the typical operating range in display applications. The results provide a deeper understanding of the OLED emission mechanism, and the proposed OLED structure can significantly benefit high-performance OLED displays.</p><h3>Graphical Abstract</h3>\u0000<div><figure><div><div><picture><source><img></source></picture></div></div></figure></div></div>","PeriodicalId":536,"journal":{"name":"Electronic Materials Letters","volume":"20 3","pages":"232 - 242"},"PeriodicalIF":2.1,"publicationDate":"2023-08-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46451038","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-07-25DOI: 10.1007/s13391-023-00449-w
Soo Young Jung, Hyung-Jin Choi, Jun Young Lee, Min-Seok Kim, Ruiguang Ning, Dong-Hun Han, Seong Keun Kim, Sung Ok Won, June Hyuk Lee, Ji-Soo Jang, Ho Won Jang, Seung-Hyub Baek
Epitaxial buffer layers such as ceria (CeO2)/yttria-stabilized zirconia (YSZ) allow the direct integration of functional oxide single crystal thin films on silicon (Si). Microcracks in the buffer layer, often evolving from the large thermal tensile stress, are detrimental to the integration of high-quality complex oxide thin films on Si. In this study, we investigated the evolution of microcracks in sputter-grown epitaxial CeO2 layers by systematically varying the sputtering power and thickness of CeO2 thin films on YSZ single crystal (low thermal mismatch) and YSZ-buffered Si (high thermal mismatch) substrates. Using a plane stress model, we revealed that as the sputtering power increased, the epitaxial CeO2 thin films tended to be more compressively strained at the growth temperature. This could accommodate the tensile strain arising during cooling to room temperature, thereby suppressing the evolution of microcracks. Our result provides not only a method to suppress microcracks in the oxide heterostructure on Si, but also a tool to control their strain state, by controlling their growth parameters.
{"title":"Evolution of Microcracks in Epitaxial CeO2 Thin Films on YSZ-Buffered Si","authors":"Soo Young Jung, Hyung-Jin Choi, Jun Young Lee, Min-Seok Kim, Ruiguang Ning, Dong-Hun Han, Seong Keun Kim, Sung Ok Won, June Hyuk Lee, Ji-Soo Jang, Ho Won Jang, Seung-Hyub Baek","doi":"10.1007/s13391-023-00449-w","DOIUrl":"10.1007/s13391-023-00449-w","url":null,"abstract":"<div><p>Epitaxial buffer layers such as ceria (CeO<sub>2</sub>)/yttria-stabilized zirconia (YSZ) allow the direct integration of functional oxide single crystal thin films on silicon (Si). Microcracks in the buffer layer, often evolving from the large thermal tensile stress, are detrimental to the integration of high-quality complex oxide thin films on Si. In this study, we investigated the evolution of microcracks in sputter-grown epitaxial CeO<sub>2</sub> layers by systematically varying the sputtering power and thickness of CeO<sub>2</sub> thin films on YSZ single crystal (low thermal mismatch) and YSZ-buffered Si (high thermal mismatch) substrates. Using a plane stress model, we revealed that as the sputtering power increased, the epitaxial CeO<sub>2</sub> thin films tended to be more compressively strained at the growth temperature. This could accommodate the tensile strain arising during cooling to room temperature, thereby suppressing the evolution of microcracks. Our result provides not only a method to suppress microcracks in the oxide heterostructure on Si, but also a tool to control their strain state, by controlling their growth parameters.</p><h3>Graphical Abstract</h3><div><figure><div><div><picture><source><img></source></picture></div></div></figure></div></div>","PeriodicalId":536,"journal":{"name":"Electronic Materials Letters","volume":"20 4","pages":"484 - 490"},"PeriodicalIF":2.1,"publicationDate":"2023-07-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47955455","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-06-30DOI: 10.1007/s13391-023-00448-x
Thanh-Tung Duong, Phuong-Nam Tran, Tuan-Pham Van, Duy-Hung Nguyen, Van-Dang Tran
This study demonstrates a simple centrifugal coating method to prepare high-quality pure cubic phase CsPbBr3 nanocrystal film. The resultant perovskite layers possess a uniform and dense 500 nm-thick, with a bandgap of 2.38 eV, a low trap-state density of 6.9 × 10− 15 cm− 3, and carrier mobility of approximately 19.8 cm2V− 1s− 1. Furthermore, CsPbBr3 NCs-based self-powered photodetectors with high charge carriers’ charge transfer are fabricated. The device shows a low dark current density of 1.93 × 10− 7 A/cm2 at room temperature. Such photodetectors show the highest responsivity of 3.0 AW− 1, specific detectivity of 1.2 × 1013 Jones, and external quantum efficiency (EQE) of 920% at zero bias voltage. The proposed method shows significant promise for use in the lab fabrication of optoelectronic devices based on thin films of nanocrystal perovskite materials.
{"title":"A Dense, Pinholes-free Pure Cubic Phase CsPbBr3 Nanocrystals Film for High-performance Photodetector","authors":"Thanh-Tung Duong, Phuong-Nam Tran, Tuan-Pham Van, Duy-Hung Nguyen, Van-Dang Tran","doi":"10.1007/s13391-023-00448-x","DOIUrl":"10.1007/s13391-023-00448-x","url":null,"abstract":"<p>This study demonstrates a simple centrifugal coating method to prepare high-quality pure cubic phase CsPbBr<sub>3</sub> nanocrystal film. The resultant perovskite layers possess a uniform and dense 500 nm-thick, with a bandgap of 2.38 eV, a low trap-state density of 6.9 × 10<sup>− 15</sup> cm<sup>− 3</sup>, and carrier mobility of approximately 19.8 cm<sup>2</sup>V<sup>− 1</sup>s<sup>− 1</sup>. Furthermore, CsPbBr<sub>3</sub> NCs-based self-powered photodetectors with high charge carriers’ charge transfer are fabricated. The device shows a low dark current density of 1.93 × 10<sup>− 7</sup> A/cm<sup>2</sup> at room temperature. Such photodetectors show the highest responsivity of 3.0 AW<sup>− 1</sup>, specific detectivity of 1.2 × 10<sup>13</sup> Jones, and external quantum efficiency (EQE) of 920% at zero bias voltage. The proposed method shows significant promise for use in the lab fabrication of optoelectronic devices based on thin films of nanocrystal perovskite materials.</p>","PeriodicalId":536,"journal":{"name":"Electronic Materials Letters","volume":"20 2","pages":"217 - 223"},"PeriodicalIF":2.1,"publicationDate":"2023-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42909745","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-06-29DOI: 10.1007/s13391-023-00447-y
Jiangbin Su, Xiumei Zhu, Longlong Chen, Yu Liu, Hao Qi, Zuming He, Bin Tang
WO3 thin films were prepared on indium-tin oxide (ITO) glass substrates at different substrate temperature by radio frequency magnetron sputtering. Then the films were soaked in five organic solvents of acetone, ethanol, cyclohexane, acetonitrile and ethyl acetate for 48 h, respectively. The changes in the microstructure, surface morphology and electrochromic (EC) properties of WO3 thin films before and after the immersion treatment were systematically studied. It was found that after soaking in ethanol, the optical modulation of amorphous WO3 thin films deposited at room temperature increased from 50 to 85%, showing excellent EC performance. Moreover, the immersion treatment in ethanol is also helpful for improving the EC properties of amorphous WO3 thin films prepared at elevated substrate temperature. However, after immersion in the other organic solvents, the optical modulation of WO3 thin films increased less (for acetone: 77%) or even decreased significantly (for cyclohexane, acetonitrile and ethyl acetate: 31%, 30% and 35%, respectively). In addition, the immersion treatment in ethanol cannot improve the optical modulation of crystalline WO3 thin films prepared at 600 °C, which dropped from 58 to 40%. The authors believe that this is mainly related to the different dredging effects of various organic solvents on the transport channels of Li-ions and electrons in WO3 thin films. Therefore, this work provides a new approach for the optimization of EC performance of amorphous WO3 thin films.
{"title":"Optimization of Optical Modulation in Amorphous WO3 Thin Films","authors":"Jiangbin Su, Xiumei Zhu, Longlong Chen, Yu Liu, Hao Qi, Zuming He, Bin Tang","doi":"10.1007/s13391-023-00447-y","DOIUrl":"10.1007/s13391-023-00447-y","url":null,"abstract":"<p>WO<sub>3</sub> thin films were prepared on indium-tin oxide (ITO) glass substrates at different substrate temperature by radio frequency magnetron sputtering. Then the films were soaked in five organic solvents of acetone, ethanol, cyclohexane, acetonitrile and ethyl acetate for 48 h, respectively. The changes in the microstructure, surface morphology and electrochromic (EC) properties of WO<sub>3</sub> thin films before and after the immersion treatment were systematically studied. It was found that after soaking in ethanol, the optical modulation of amorphous WO<sub>3</sub> thin films deposited at room temperature increased from 50 to 85%, showing excellent EC performance. Moreover, the immersion treatment in ethanol is also helpful for improving the EC properties of amorphous WO<sub>3</sub> thin films prepared at elevated substrate temperature. However, after immersion in the other organic solvents, the optical modulation of WO<sub>3</sub> thin films increased less (for acetone: 77%) or even decreased significantly (for cyclohexane, acetonitrile and ethyl acetate: 31%, 30% and 35%, respectively). In addition, the immersion treatment in ethanol cannot improve the optical modulation of crystalline WO<sub>3</sub> thin films prepared at 600 °C, which dropped from 58 to 40%. The authors believe that this is mainly related to the different dredging effects of various organic solvents on the transport channels of Li-ions and electrons in WO<sub>3</sub> thin films. Therefore, this work provides a new approach for the optimization of EC performance of amorphous WO<sub>3</sub> thin films.</p>","PeriodicalId":536,"journal":{"name":"Electronic Materials Letters","volume":"20 2","pages":"131 - 139"},"PeriodicalIF":2.1,"publicationDate":"2023-06-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47548237","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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