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热退偏损耗完全补偿的千赫兹电光调Q Nd:YAG激光器 总被引：3，自引：1，他引：3
为了同时补偿固体增益介质的热致双折射及热透镜效应,进一步提高重复频率1 kHz激光二极管(LD)侧向抽运高平均功率电光调QNd∶YAG激光器的输出功率,设计了一种完全消除热退偏损耗的双调Q开关谐振腔结构,此结构在传统调Q谐振腔的基础上沿着偏振片的退偏方向增加了一个调Q谐振支路,并使得激光从增益介质方向输出.实验结果表明,此激光器的单脉冲能量比单Q开关结构的非补偿腔输出能量高出74.7%.当侧面抽运的激光二极管输出脉冲能量达到307 mJ时,激光输出能量达到26.2 mJ,光-光转换效率为8.5%,光束发散角为1 mrad. 相似文献
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OLEDs: Achieving High‐Performance Nondoped OLEDs with Extremely Small Efficiency Roll‐Off by Combining Aggregation‐Induced Emission and Thermally Activated Delayed Fluorescence (Adv. Funct. Mater. 13/2017) 
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下载免费PDF全文 Jingjing Guo Xiang‐Long Li Han Nie Wenwen Luo Shifeng Gan Shimin Hu Rongrong Hu Anjun Qin Zujin Zhao Shi‐Jian Su Ben Zhong Tang 《Advanced functional materials》2017,27(13)
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Jingjing Guo Xiang‐Long Li Han Nie Wenwen Luo Shifeng Gan Shimin Hu Rongrong Hu Anjun Qin Zujin Zhao Shi‐Jian Su Ben Zhong Tang 《Advanced functional materials》2017,27(13)
Luminescent materials with thermally activated delayed fluorescence (TADF) can harvest singlet and triplet excitons to afford high electroluminescence (EL) efficiencies for organic light‐emitting diodes (OLEDs). However, TADF emitters generally have to be dispersed into host matrices to suppress emission quenching and/or exciton annihilation, and most doped OLEDs of TADF emitters encounter a thorny problem of swift efficiency roll‐off as luminance increases. To address this issue, in this study, a new tailor‐made luminogen (dibenzothiophene‐benzoyl‐9,9‐dimethyl‐9,10‐dihydroacridine, DBT‐BZ‐DMAC) with an unsymmetrical structure is synthesized and investigated by crystallography, theoretical calculation, spectroscopies, etc. It shows aggregation‐induced emission, prominent TADF, and interesting mechanoluminescence property. Doped OLEDs of DBT‐BZ‐DMAC show high peak current and external quantum efficiencies of up to 51.7 cd A?1 and 17.9%, respectively, but the efficiency roll‐off is large at high luminance. High‐performance nondoped OLED is also achieved with neat film of DBT‐BZ‐DMAC, providing excellent maxima EL efficiencies of 43.3 cd A?1 and 14.2%, negligible current efficiency roll‐off of 0.46%, and external quantum efficiency roll‐off approaching null from peak values to those at 1000 cd m?2. To the best of the authors' knowledge, this is one of the most efficient nondoped TADF OLEDs with small efficiency roll‐off reported so far. 相似文献
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Haibo Zhang Claudia Groh Qi Zhang Wook Jo Kyle G. Webber Jürgen Rdel 《Advanced Electronic Materials》2015,1(6)
A lead‐free relaxor (RE)/ferroelectric (FE) 0–3 composite was developed with a large strain that resulted from the electric‐field‐induced ergodic relaxor‐to‐ferroelectric phase transition at a relatively low operational field of 4 kV mm−1. The composite comprised of 70 vol% 0.91Bi1/2Na1/2TiO3–0.06BaTiO3–0.03AgNbO3 RE matrix and 30 vol% 0.93Bi1/2Na1/2TiO3–0.07BaTiO3 FE seed shows a normalized strain, , of 824 pm V−1 at room temperature. In order to explore the underlying mechanism of this composite effect, two multilayer ceramics with alternating RE and FE layers are also prepared, one with the layers parallel (polarization‐coupled multilayer) and the other with the layers perpendicular (strain‐coupled multilayer) to the electroded surfaces. It is found that in addition to polarization coupling, the strain coupling effect also plays a critical role in the reduction of the RE–FE phase transition field. The switching dynamics is highlighted with time‐dependent piezoforce microscopy in the vicinity of the FE/RE interface. 相似文献
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Yongtao Liu Anton V. Ievlev Liam Collins Alex Belianinov Jong K. Keum Mahshid Ahmadi Stephen Jesse Scott T. Retterer Kai Xiao Jingsong Huang Bobby G. Sumpter Sergei V. Kalinin Bin Hu Olga S. Ovchinnikova 《Advanced Electronic Materials》2020,6(4)
Metal halide perovskites (MHPs) have attracted broad research interest due to their outstanding optoelectronic performance. This performance has been attributed in part to the presence of polarization in these materials. However, the precise effects of chemical environment and strain condition on the polar states in MHPs have largely been missing. It is revealed for the first time that chemical gradient is directly coupled with strain gradient in CH3NH3PbI3. This strain–chemical gradient induces an electric polarization that can potentially affect charge carrier dynamics. Furthermore, it is unveiled that this electric polarization—unlike ferroelectricity that only exists in noncentrosymmetric materials—can be present in both tetragonal and cubic phases of CH3NH3PbI3. This suggests that the strain–chemical gradient induced polarization is a more convincing explanation of the outstanding photovoltaic properties of MHPs than the hotly debated ferroelectric polarization. Finally, a mechanism of how this polarization impacts photovoltaic action is proposed, which offers insightful advances in the development of MHPs. 相似文献
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随着基于硅微加工技术的微机电(MEMS)技术的发展,搭建低成本的自适应光学系统以校正激光束畸变成为可能。首先根据模态耦合理论分析了热畸变对光束质量的影响,并用数值方法得到理想基模和畸变基模耦合振幅与泽尼克(Zernike)畸变之间的关系。然后采用一种新型的微机电变形反射镜搭建了一个闭环自适应光学实验系统,用来对热畸变激光光束进行补偿,并对自适应闭环控制方法进行了研究。闭环实验结果显示闭环自适应光学实验系统能很好地改善激光束质量,斯特列尔比(StrehlRatio)平均可以达到80%。 相似文献
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Jiajie Zeng Jingjing Guo Hao Liu Zujin Zhao Ben Zhong Tang 《Advanced functional materials》2020,30(17)
Increasing exciton utilization and reducing exciton annihilation are crucial to achieve high performance of organic light‐emitting diodes (OLEDs), which greatly depend on molecular engineering of emitters and hosts. A novel luminogen (SBF‐BP‐DMAC) is synthesized and characterized. Its crystal and electronic structures, thermal stability, electrochemical behavior, carrier transport, photoluminescence, and electroluminescence are investigated. SBF‐BP‐DMAC exhibits enhanced photoluminescence and promotes delayed fluorescence in solid state and bipolar carrier transport ability, and thus holds multifunctionality of emitter and host for OLEDs. Using SBF‐BP‐DMAC as an emitter, the nondoped OLEDs exhibit maximum electroluminescence (EL) efficiencies of 67.2 cd A?1, 65.9 lm W?1, and 20.1%, and the doped OLEDs provide maximum EL efficiencies of 79.1 cd A?1, 70.7 lm W?1, and 24.5%. A representative orange phosphor, Ir(tptpy)2acac, is doped into SBF‐BP‐DMAC for OLED fabrication, giving rise to superior EL efficiencies of 88.0 cd A?1, 108.0 lm W?1, and 26.8% for orange phosphorescent OLEDs, and forward‐viewing EL efficiencies of 69.3 cd A?1, 45.8 lm W?1, and 21.0% for two‐color hybrid warm‐white OLEDs. All of these OLEDs can retain high EL efficiencies at high luminance, with very small efficiency roll‐offs. The outstanding EL performance demonstrates the great potentials of SBF‐BP‐DMAC in practical display and lighting devices. 相似文献
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Amartya Mukhopadhyay Fei Guo Anton Tokranov Xingcheng Xiao Robert H. Hurt Brian W. Sheldon 《Advanced functional materials》2013,23(19):2397-2404
Novel carbon films with different graphene layer orientations are investigated as electrode materials for Li‐ion batteries. It is demonstrated that engineering the crystallographic orientation with graphene layers oriented perpendicular to the surface substantially alters stress evolution during Li insertion. With this crystallographic orientation the intercalating/de‐intercalating Li‐ions also have direct access to the graphene interlayer spaces, resulting in higher capacity at faster electrochemical cycling, compared to carbon films with graphene layers parallel to the film surface. Electrodes with perpendicular alignment are prepared by supramolecular synthesis using either spin coating or bar coating of chromonic liquid crystal precursors into precursor organic films followed by in situ carbonization. These materials are compared with in situ stress measurements during lithiation/delithiation cycles, and the bar‐coated films exhibit a highly anisotropic stress which is consistent with long‐range alignment of the graphene layers. In contrast, the in‐plane stresses in the spin‐coated films are isotropic, which is consistent with the presence of randomly oriented domains (still with graphene layers oriented perpendicular to the surface). Overall, the use of thin film graphitic materials with controlled crystallographic orientations provides a valuable platform for investigating the impact of graphene structure on the properties of Li‐ion battery electrode materials. 相似文献
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Zhiqi Liu Zexin Feng Han Yan Xiaoning Wang Xiaorong Zhou Peixin Qin Huixin Guo Ronghai Yu Chengbao Jiang 《Advanced Electronic Materials》2019,5(7)
Antiferromagnets naturally exhibit three obvious advantages over ferromagnets for memory device applications: insensitivity to external magnetic fields, much faster spin dynamics (≈THz), and higher packing density due to the absence of any stray field. Recently, antiferromagnetic spintronics has emerged as a cutting‐edge field in the magnetism community. The key mission of this rapidly rising field is to steer the spins or spin axes of antiferromagnets via external stimuli and then realize advanced devices based on their physical property changes. Herein, the state‐of‐the‐art of antiferromagnetic spintronics is presented. Subsequently, the history of ferromagnetic/ferroelectric multiferroic composites is briefly revisited. Finally, an ultralow‐power, long‐range, and magnetic‐field‐insensitive approach for harnessing antiferromagnetic spins based on recent experimental progress, i.e., piezoelectric strain control, is introduced. Relevant theoretical and experimental studies have formed an attractive new branch in antiferromagnetic spintronics, which is dubbed “antiferromagnetic piezospintronics.” 相似文献
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Yongjae Cho Ji Hoon Park Minju Kim Yeonsu Jeong Jongtae Ahn Taeyoung Kim Hyunyong Choi Yeonjin Yi Seongil Im 《Advanced functional materials》2018,28(39)
Since transition metal dichalcogenide (TMD) semiconductors are found as 2D van der Waals materials with a discrete energy bandgap, many 2D‐like thin field effect transistors (FETs) and PN diodes are reported as prototype electrical and optoelectronic devices. As a potential application of display electronics, transparent 2D FET devices are also reported recently. Such transparent 2D FETs are very few in report, yet no p‐type channel 2D‐like FETs are seen. Here, 2D‐like thin transparent p‐channel MoTe2 FETs with oxygen (O2) plasma‐induced MoOx/Pt/indium‐tin‐oxide (ITO) contact are reported for the first time. For source/drain contact, 60 s short O2 plasma and ultrathin Pt‐deposition processes on MoTe2 surface are sequentially introduced before ITO thin film deposition and patterning. As a result, almost transparent 2D FETs are obtained with a decent mobility of ≈5 cm2 V?1 s?1, a high ON/OFF current ratio of ≈105, and 70% transmittance. In particular, for normal MoTe2 FETs without ITO, O2 plasma process greatly improves the hole injection efficiency and device mobility (≈60 cm2 V?1 s?1), introducing ultrathin MoOx between Pt source/drain and MoTe2. As a final device application, a photovoltaic current modulator, where the transparent FET stably operates as gated by photovoltaic effects, is integrated. 相似文献
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管状激光介质的光学性质 总被引：2，自引：0，他引：2
针对管状激光介质的热透镜效应,提出“C1判据”和“热感应光线主轴”的观点;推导了二维光线矩阵和热透镜焦距;并指出提高光束质量的主要方法。 相似文献
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Hongkyu Eoh Han Sol Kang Min Ju Kim Min Koo Tae Hyun Park Yeongsik Kim Hanwhuy Lim Du Yeol Ryu Eunkyoung Kim June Huh Youngjong Kang Cheolmin Park 《Advanced functional materials》2019,29(42)
In spite of efforts to fabricate stimuli‐sensitive structural colors (SCs) of self‐assembled block copolymer (BCP) photonic crystals (PCs) with potential applications in displays, media boards, and sensors, few studies have demonstrated BCP PCs suitable for high‐density nonvolatile information storage. Herein, a simple but robust route for multilevel nonvolatile information recording using a BCP PC is presented. The proposed method is based on the spatially controlled crosslinking of microdomains of a BCP PC induced by photothermal conversion. Photothermal SC writing is accomplished via time‐ and position‐controlled laser exposure on thin poly(styrene‐block‐quaternized 2‐vinyl pyridine) (PS‐b‐QP2VP) PC films deposited on a layer of poly(3,4‐ethylenedioxythiophene) doped with tosylate (PP‐PEDOT). Upon near‐infrared (NIR) irradiation of this structure, the PP‐PEDOT underlayer converts the NIR light into thermal energy in the locally irradiated region, which is subsequently transferred to the BCP top layer consisting of alternating in‐plane PS and QP2VP lamellar stacks. The QP2VP layers are vulnerable to thermal crosslinking, giving rise to locally programmable SCs. The degree of crosslinking of the QP2VP domains depends on the laser power and exposure time, which allows for multi‐SC recording per spot, leading to a novel multilevel optical recording medium based on BCP PCs. 相似文献
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Zuhuang Chen Zhenlin Luo Chuanwei Huang Yajun Qi Ping Yang Lu You Chuansheng Hu Tom Wu Junling Wang Chen Gao Thirumany Sritharan Lang Chen 《Advanced functional materials》2011,21(1):133-138
A morphotropic phase boundary driven by epitaxial strain has been observed in lead‐free multiferroic BiFeO3 thin films and the strain‐driven phase transitions have been widely reported as iso‐symmetric Cc‐Cc by recent works. In this paper, it is suggested that the tetragonal‐like BiFeO3 phase identified in epitaxial films on (001) LaAlO3 single crystal substrates is monoclinic MC. This MC phase is different from the MA type monoclinic phase reported in BiFeO3 films grown on low mismatch substrates, such as SrTiO3. This is confirmed not only by synchrotron X‐ray studies but also by piezoresponse force microscopy measurements. The polarization vectors of the tetragonal‐like phase lie in the (100) plane, not the (11 0) plane as previously reported. A phenomenological analysis is proposed to explain the formation of MC Phase. Such a low‐symmetry MC phase, with its linkage to MA phase and the multiphase coexistence open an avenue for large piezoelectric response in BiFeO3 films and shed light on a complete understanding of possible polarization rotation paths and enhanced multiferroicity in BiFeO3 films mediated by epitaxial strain. This work may also aid the understanding of developing new lead‐free strain‐driven morphotropic phase boundary in other ferroic systems. 相似文献
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Mengxi Wang Qi Guo Xiaoguang Xu Zeyu Zhang Zengyao Ren Libai Zhu Kangkang Meng Jikun Chen Yong Wu Jun Miao Yong Jiang 《Advanced Electronic Materials》2020,6(7)
A strain‐mediated perpendicular magnetic anisotropy (PMA) and current‐induced magnetization switching via spin–orbit torque (SOT) in PbMg1/3Nb2/3O3‐PbTiO3 (PMN‐PT)/Ta/Pt/Co/Pt ferromagnetic heterostructures are reported. It is found that the PMA changes regularly with the preloaded lateral electric field. The SOT‐based current‐induced magnetization switching also shows a reversible trend via applying a lateral electric field. Domain wall propagation driven by electric field is observed directly under a fixed perpendicular magnetic field by magnetic optical Kerr (MOKE) microscope. These behaviors can be attributed to the strain from the PMN‐PT substrates induced by the piezoelectric effect under electric field. Basing on the domain wall motion mechanism, repeatable resistance states of the Hall bar can be controlled by external electric field under a small auxiliary magnetic field, which enables the information recorded in the device can be programmed by voltage. This study provides a potential method to design the electric field controlled spintronic devices. 相似文献
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Shuai Wang Azatuhi Ayrikyan Haibo Zhang Kyle G. Webber Bai‐Xiang Xu 《Advanced Electronic Materials》2019,5(2)
The interface coupling effect of multilayer lead‐free ceramic/ceramic relaxor/ferroelectric composites is studied by finite element–based phase‐field simulations. The macroscopic electromechanical behavior of such composite systems is influenced by both polarization and strain coupling through the electrical and mechanical interaction of connected layers. Separating such interconnected phenomena is difficult experimentally. Here, we direct investigate different coupling effect by introducing soft and charge interphase layers in the serial‐type layer composite model. The large strain response of the composite results from the electric field–induced nonpolar–polar phase transition of the relaxor constituent. A new relaxor phase‐field model is first developed to reproduce this phase transition and parameterized by fitting the measured hysteresis loops. It is then directly compared to the experimental results of the serial‐type composite composed of 0.91Bi1/2Na1/2TiO3–0.06BaTiO3–0.03AgNbO3 and 0.93Bi1/2Na1/2TiO3–0.07BaTiO3. Results show that the lateral strain coupling in the serial layer contributes considerably to the large signal piezoelectric coefficient . The primary enhancement in is due a reduction in the remanent strain of the ferroelectric layer caused by the lateral mismatch. Moreover, charge interphase layers in the composite can introduce an internal electric field, leading to a weaker large‐signal response compared with the composite with coherent interfaces. 相似文献