Distinguishing Carrier Transport and Interfacial Recombination at Perovskite-Transport Layer Interfaces Using Ultrafast Spectroscopy and Numerical Simulation
Edward Butler-Caddle, K. D. G. Imalka Jayawardena, Anjana Wijesekara, Rebecca L Milot, James Lloyd-Hughes
In perovskite solar cells, photovoltaic action is created by charge transport layers (CTLs) either side of the light-absorbing metal halide perovskite semiconductor. Hence, the rates for desirable charge extraction and unwanted interfacial recombination at the perovskite-CTL interfaces play a critical role for device efficiency. Here, the electrical properties of perovskite-CTL bilayer heterostructures are obtained using ultrafast THz and optical studies of the charge carrier dynamics after pulsed photoexcitation, combined with a physical model of charge carrier transport that includes the prominent Coulombic forces that arise after selective charge extraction into a CTL, and cross-interfacial recombination. The charge extraction velocity at the interface and the ambipolar diffusion coefficient within the perovskite are determined from the experimental decay profiles for heterostructures with three of the highest performing CTLs, namely C$_{60}$, PCBM and Spiro-OMeTAD. Definitive targets for the further improvement of devices are deduced: fullerenes deliver fast electron extraction, but suffer from a large rate constant for cross-interface recombination or hole extraction. Conversely, Spiro-OMeTAD exhibits slow hole extraction but does not increase the perovskite's surface recombination rate, likely contributing to its success in solar cell devices.
Ultrafast Measurements of the Interfacial Spin Seebeck Effect in Au and Rare-Earth Iron Garnet Bilayers
我们研究了金/铁石榴石界面上的皮秒自旋电流响应于超快激光加热的Au膜中的电子。在光加热后的皮秒内，由于金属中的电子和绝缘体中的磁振子之间的界面温度差，会出现界面自旋电流。本文报道了Au与稀土铁石榴石绝缘体（RE $_3$ Fe $_5$ O $_{12}$，其中RE为Y，Eu，Tb，Tm）之间界面纵向自旋Seebeck效应的测量结果。我们使用时域热反射（TDTR）的测量来表征超快光加热的双层的热响应。我们使用时间分辨的磁光克尔效应（TR-MOKE）测量的Au层来测量自旋积累的时间演化的Au膜。我们观察到Au/TmIG之间的自旋Seebeck效应是Au/YIG双层的三倍。Au中的电子与TmIG层中的磁振子之间的界面热导为~3 $\frac{MW}{m^2 K}$。
Ultrafast polarization control of zero-bias photocurrent and terahertz emission in hybrid organic perovskites
甲基碘化铅铵（Methylammonium lead iodide，简称MAI）是一种基准的混合有机钙钛矿材料，用于低成本的印刷太阳能电池，其功率转换效率超过20%。然而，光与物质相互作用的性质以及设备操作背后的确切物理机制目前仍有争议。在这里，我们报告室温下，超快光电流和自由空间太赫兹（THz）发射产生的无偏置的150 fs光脉冲引起的。所观察到的光响应的偏振依赖性是一致的体光伏效应（BPVE）所造成的注入和移位电流的组合。我们相信，这种观察可以揭示低复合，和长的载流子扩散长度，由于间接带隙。此外，弹道性质的偏移和注入BPVE光电流可以使第三代钙钛矿太阳能电池具有超过Shockley_Queisser极限的效率。我们的观察也为钙钛矿自旋电子学和可调谐THz源开辟了新的途径。
Indirect optical manipulation of the antiferromagnetic order of insulating NiO by ultrafast interfacial energy transfer
RPTU University Kaiserslautern-Landau（莱布尼茨技术大学凯泽斯劳滕-兰道分校）；Johannes Gutenberg-University Mainz（约翰内斯·古腾堡美因茨大学）；Tohoku University（东北大学）；The University of Tokyo（东京大学）；Japan Atomic Energy Agency（日本原子能研究开发机构）；RIKEN Center for Emergent Matter Science (CEMS)（理化学研究所涌现物质科学中心）；University of Augsburg（奥格斯堡大学）
Interfacial effect on the optoelectronic and piezoelectric properties of Ge-Sn terminated Halide Perovskite heterostructure from first-principles study
Pachhunga University College（帕丘恩加大学学院）；King Saud University（沙特国王大学）
Confinement-induced Ultrafast Conductivity in 2D Perovskites resolved by correlative Terahertz-NIR Spectroscopy
University of Bayreuth（拜罗伊特大学）；Ulm University（乌尔姆大学）；Bayreuth Institute of Macromolecular Research (BIMF)（拜罗伊特大分子研究所）；Bavarian Polymer Institute (BPI)（巴伐利亚聚合物研究所）；The University of Melbourne（墨尔本大学）
Ultrafast Exciton-Polariton Transport and Relaxation in Halide Perovskite
National Center for Nanoscience and Technology（中国科学院国家纳米科学中心）；CAS Key Laboratory of Standardization and Measurement for Nanotechnology（中国科学院纳米技术标准化与测量重点实验室）；University of Chinese Academy of Sciences（中国科学院大学）；School of Materials Science and Engineering, Peking University（北京大学材料科学与工程学院）；Nanyang Technological University（南洋理工大学）；Paderborn University（帕德博恩大学）
Tuning Electronic and Optical Properties of 2D/3D Construction based on Hybrid Perovskites through Interfacial Charge Transfer: Towards Higher Efficiency Solar Cells
Interfacial Structure of SrZr$_{x}$Ti$_{1-x}$O$_3$ films on Ge
用同步辐射X射线衍射和第一性原理密度泛函理论研究了生长在半导体Ge衬底上的SrZr $_{x}$ Ti $_{1-x}$ O $_3$薄膜的界面结构.通过系统地调节Zr含量x，可以区分界面处的键合和外延应变对膜的物理结构的影响。发现界面钙钛矿层被极化作为垂直于钙钛矿/半导体界面的阳离子-阴离子位移的结果。我们发现在SrZr $_{x}$ Ti $_{1-x}$ O $_3$ /Ge界面观察到的屈曲和价带偏移之间的相关性。极性结构的理论价带偏移与报道的X射线光电子能谱学测量结果一致。这些结果具有重要意义的功能氧化物材料与既定的半导体为基础的技术的集成。
Transient Ferromagnetism in Ultrafast Phase Transitions in Perovskites under XUV Irradiation: A Comparative Study of SrTiO3 and KTaO3
Institute of Physics, Czech Academy of Sciences（捷克科学院物理研究所）；Faculty of Nuclear Sciences and Physical Engineering, Czech Technical University in Prague（布拉格捷克理工大学核科学与物理工程学院）；Institute of Plasma Physics, Czech Academy of Sciences（捷克科学院等离子体物理研究所）
Wavelength-Dependent Photoluminescence Mapping of Depth-Dependent Degradation Under Thermal Stress in Phenethylammonium Tetrafluoroborate Treated Perovskite Solar Cells
Tunnel-Barrier-Engineered Ultrafast Demagnetization and Spin Transport in Graphene-Based Heterostructures
S. N. Bose National Center for Basic Sciences（S.N. 玻色基础科学国家中心）；Indian Institute of Science Education and Research Kolkata（加尔各答印度科学与教育研究所）；Uppsala University（乌普萨拉大学）
Effect of interfacial Fe3O4 nanoparticles on the microstructure and mechanical properties of textured alumina densified by ultrafast high-temperature sintering
