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光谱稳定的混合卤素蓝光钙钛矿LED设计
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作者 冯继雨 刘敏 +3 位作者 屈正国 赵东楠 李道鹏 史同飞 《物理学报》 北大核心 2025年第14期324-332,共9页
钙钛矿材料因其可调带隙和高荧光效率成为发光二极管(LED)的研究热点,但混合卤素(Br^(-)/Cl^(-))体系的相分离问题严重制约蓝光LED的稳定性.本文提出通过调控前驱体中铯铅含量比,形成CsPb(Br_(1-x)Cl_(x))_(3)/Cs4Pb(Br_(1-x)Cl_(x))_(6... 钙钛矿材料因其可调带隙和高荧光效率成为发光二极管(LED)的研究热点,但混合卤素(Br^(-)/Cl^(-))体系的相分离问题严重制约蓝光LED的稳定性.本文提出通过调控前驱体中铯铅含量比,形成CsPb(Br_(1-x)Cl_(x))_(3)/Cs4Pb(Br_(1-x)Cl_(x))_(6)复合相结构.结果表明,Cs4Pb(Br_(1-x)Cl_(x))_(6)相的纳米晶颗粒聚集并包覆在CsPb(Br_(1-x)Cl_(x))_(3)大晶粒周围,物理上阻隔了卤素离子的迁移,避免了相分离的产生.宽带隙的Cs4Pb(Br_(1-x)Cl_(x))_(6)还引入了量子限域效应,钝化表面缺陷态,提升CsPb(Br_(1-x)Cl_(x))_(3)材料光电性能.优化后的器件在50 mA/cm2电流密度下光谱稳定性显著提升.该研究为高稳定性蓝光钙钛矿LED提供了新思路. 展开更多
关键词 钙钛矿 蓝光 发光二极管
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Cognitive and Psychosocial Accessibility to Modern Contraception: Subscales Validation
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作者 Lonkila Moussa Zan Clémentine Rossier 《Health》 2023年第7期746-757,共12页
While studies have examined physical access to services, cognitive and psychosocial barriers to contraceptive use have received less attention, despite their impact on access. Research shows that fours main dimensions... While studies have examined physical access to services, cognitive and psychosocial barriers to contraceptive use have received less attention, despite their impact on access. Research shows that fours main dimensions exist under the broad concept of cognitive and psychosocial access. This study aims to validate the construction of these dimensions and measure the relation between them and their links with modern contraceptive use. We utilized a questionnaire module to collect 15 questions measuring these dimensions through the 6<sup>th</sup> round of the Performance monitoring and accountability 2020 (PMA2020) survey in Burkina in 2019. We employed the scale validation technique to choose appropriate measures (observable indicators or items) for constructing each latent dimension (unobservable) in our study. The items consisted of questions that utilized a 5-point Likert scale or dichotomous responses to capture various psychosocial aspects. To assess the validity, reliability, convergence, and divergence of the latent dimensions and items, we utilized the validscale command in Stata. The validation process confirmed the reliability of all the dimensions. Contraceptive approval is more aligned with birth spacing rather than birth limiting, reflecting prevailing social perceptions. Women’s contraceptive agency was found to be more associated with their ability to discuss and negotiate with their partners rather than independent decision-making. Correlations between dimensions were generally weak, but the levels of knowledge, agency, and approval of contraception are positively correlated with contraceptive use and intention to use. Giving women more decision-making power and providing information to address side-effect concerns can enhance contraceptive approval. 展开更多
关键词 Cognitive Dimensions Psychosocial Dimensions CONTRACEPTION Intention to Use Side Effects
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Measuring Cognitive and Psychosocial Accessibility to Modern Contraception: A Comprehensive Framework
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作者 Lonkila Moussa Zan Clémentine Rossier Caroline Moreau 《Health》 2024年第7期578-591,共14页
Nowadays, more than ever, the improvement of access to family planning (FP) has become an international goal. What constitutes access to FP? Current human rights-based contraceptive guidelines indicate that access beg... Nowadays, more than ever, the improvement of access to family planning (FP) has become an international goal. What constitutes access to FP? Current human rights-based contraceptive guidelines indicate that access begins as soon as women or couples express a desire to avoid pregnancy and their risk of unintended pregnancy is established. However, few studies have sought to define and measure cognitive and psychosocial access to contraception. To propose a comprehensive framework for the cognitive and psychosocial accessibility of contraception, we critically analyzed the literature on attitudes toward FP. The main dimensions that emerged were knowledge about FP, fear of side effects, approval of contraception, and contraceptive agency. We then identified and adjusted some questions that can capture these dimensions more comprehensively. As a result, we developed a questionnaire module comprising 15 questions, which was integrated into the 6th round of the PMA2020 survey in Burkina Faso in 2019. This research highlighted that previous studies have collected separate dimensions of contraceptive access, and the psychosocial dimension tended to be neglected. Our results demonstrate that it is possible to collect comprehensive data on cognitive and psychosocial dimensions of access to family planning. 展开更多
关键词 Cognitive Dimensions Psychosocial Dimensions CONTRACEPTION Intention To Use Side Effects
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Morphology and Properties of Hybrid Systems Comprising Gold Nanoparticles in CuPc Matrices
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作者 Olga Molodtsova Irina Aristova +3 位作者 Vitalii Kveder Martin Knupfer Clemens Laubschat Victor Aristov 《Journal of Physical Science and Application》 2012年第6期166-170,共5页
Transmission electron microscopy and surface- and bulk-sensitive spectroscopic methods were used to study the morphology and the electronic structure of a hybrid organic-inorganic system composed of gold nanoparticles... Transmission electron microscopy and surface- and bulk-sensitive spectroscopic methods were used to study the morphology and the electronic structure of a hybrid organic-inorganic system composed of gold nanoparticles (NP's) which were distributed in an organic matrix. Au atoms deposited onto a copper phthalocyanine (CuPc) surface diffuse into the organic matrix and self-assemble in well defined NP's with metallic properties. No formation of a continuous metallic Au film on top of the CuPc film is observed up to nominal coverages as large as 130 A. 展开更多
关键词 Hybrid organic-inorganic system nanoparticles transition electron microscopy (TEM) X-ray photoelectron spectroscopy(XPS).
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Evidence for nematic superconductivity of topological surface states in PbTaSe2 被引量:2
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作者 Tian Le Yue Sun +16 位作者 Hui-Ke Jin Liqiang Che Lichang Yin Jie Li Guiming Pang Chunqiang Xu Lingxiao Zhao Shunichiro Kittaka Toshiro Sakakibara Kazushige Machida Raman Sankar Huiqiu Yuan Genfu Chen Xiaofeng Xu Shiyan Li Yi Zhou Xin Lu 《Science Bulletin》 SCIE EI CAS CSCD 2020年第16期1349-1355,M0003,共8页
Spontaneous symmetry breaking has been a paradigm to describe the phase transitions in condensed matter physics.In addition to the continuous electromagnetic gauge symmetry,an unconventional superconductor can break d... Spontaneous symmetry breaking has been a paradigm to describe the phase transitions in condensed matter physics.In addition to the continuous electromagnetic gauge symmetry,an unconventional superconductor can break discrete symmetries simultaneously,such as time reversal and lattice rotational symmetry.In this work we report a characteristic in-plane 2-fold behaviour of the resistive upper critical field and point-contact spectra on the superconducting semimetal PbTaSe2 with topological nodal-rings,despite its hexagonal lattice symmetry(or D3 h in bulk while C3 v on surface,to be precise).The 2-fold behaviour persists up to its surface upper critical field Hc2R even though bulk superconductivity has been suppressed at its bulk upper critical field Hc2HC<<Hc2R,signaling its probable surface-only electronic nematicity.In addition,we do not observe any lattice rotational symmetry breaking signal from field-angle-dependent specific heat within the resolution.It is worth noting that such surface-only electronic nematicity is in sharp contrast to the observation in the topological superconductor candidate,CuxBi2Se3,where the nematicity occurs in various bulk measurements.In combination with theory,superconducting nematicity is likely to emerge from the topological surface states of PbTaSe2,rather than the proximity effect.The issue of time reversal symmetry breaking is also addressed.Thus,our results on PbTaSe2 shed new light on possible routes to realize nematic superconductivity with nontrivial topology. 展开更多
关键词 Nematic superconductivity Topological surface states Topological superconductor Point-contact spectroscopy
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