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Peidong Yang

Bio: Peidong Yang is an academic researcher from University of California, Berkeley. The author has contributed to research in topics: Nanowire & Perovskite (structure). The author has an hindex of 183, co-authored 562 publications receiving 144351 citations. Previous affiliations of Peidong Yang include Max Planck Society & University of California, Santa Barbara.


Papers
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Proceedings ArticleDOI
04 Dec 2003
TL;DR: In this paper, the polarization of the emitted light or lasing from individual nanostructures characterizes the coupling of spontaneous emission to cavity modes, depending both on the wavelength of emitted light and the nature of the emitting species.
Abstract: Quasi one-dimensional nanostructures are unique probes of cavity quantum electrodynamics because they are capable of exhibiting photonic and/or electronic confinement in two dimensions. The near-cylindrical geometry and sharp end facets of zinc oxide (ZnO) nanowires enable the realization of active nanoscale optical cavities that exhibit UV/blue photoluminescence (PL) waveguiding and lasing action at room temperature under appropriate optical pumping conditions. Study of individual nanostructures is crucial for isolating geometry-dependent effects, and here it is achieved through both near- and far-field microscopies. The polarization of the emitted PL or lasing from individual nanostructures characterizes the coupling of the spontaneous emission to cavity modes, depending both on the wavelength of the emitted light and the nature of the emitting species (i.e., excitons and intrinsic defects in various charge states). In addition, the spectral evolution of the lasing/PL as a function of the pump fluence indicates both exciton and electron-hole plasma dynamics. Variations of size, geometry, and material on the prototypical cylindrical ZnO nanowire lead to further observation of unique photonic and/or carrier confinement effects in novel nanostructures.

17 citations

Journal ArticleDOI
TL;DR: In this article, the authors demonstrate that vibrational relaxation in layered perovskite formed from flexible alkyl-amines as organic barriers is fast and relatively independent of the lattice temperature.
Abstract: Organic-inorganic layered perovskites, or Ruddlesden-Popper perovskites, are two-dimensional quantum wells with layers of lead-halide octahedra stacked between organic ligand barriers. The combination of their dielectric confinement and ionic sublattice results in excitonic excitations with substantial binding energies that are strongly coupled to the surrounding soft, polar lattice. However, the ligand environment in layered perovskites can significantly alter their optical properties due to the complex dynamic disorder of the soft perovskite lattice. Here, we infer dynamic disorder through phonon dephasing lifetimes initiated by resonant impulsive stimulated Raman photoexcitation followed by transient absorption probing for a variety of ligand substitutions. We demonstrate that vibrational relaxation in layered perovskite formed from flexible alkyl-amines as organic barriers is fast and relatively independent of the lattice temperature. Relaxation in layered perovskites spaced by aromatic amines is slower, although still fast relative to bulk inorganic lead bromide lattices, with a rate that is temperature dependent. Using molecular dynamics simulations, we explain the fast rates of relaxation by quantifying the large anharmonic coupling of the optical modes with the ligand layers and rationalize the temperature independence due to their amorphous packing. This work provides a molecular and time-domain depiction of the relaxation of nascent optical excitations and opens opportunities to understand how they couple to the complex layered perovskite lattice, elucidating design principles for optoelectronic devices.

16 citations

Journal ArticleDOI
18 Jul 2011-Small
TL;DR: This work reports on the fabrication of monolayer hollow inorganic silica and inorganic hybrid spheres by using electrostatic layer-by-layer self-assembly of silica nanoparticle– polymer multilayers, followed by removal of the polystyrene latex template.
Abstract: Periodically ordered composite materials can be rationally engineered with features spanning nanometer and micrometer length scales. [ 1–4 ] As a result, much progress has been made in generating thermally stable metal oxide structures with excellent crystallinity, high surface area, and controllable pore systems for applications in heterogeneous catalysis, fuel cell development, solar energy conversation, photonics, and gas-sensing. [ 5–10 ] In this process, the size of the desired features depends on the dimensions of the templates—molecular species including surfactants and block copolymers act as templates for nanoscale pores, [ 11 , 12 ] while colloidal particles template structures with pores in the nanoto microscale size regime. [ 13–18 ] Among these templating processes, colloidal crystal templates have gained more attention as new assembly techniques enable larger periodicities. In a typical method, uniformly sized colloidal particles (silica spheres, polymer spheres, or monodisperse nanocrystals) are assembled into 2D or 3D arrays. After formation of the lattice, the space between the particles is fi lled with a solution containing the precursor of the desired material composition. This precursor is deposited onto the template by drying and annealing the sample. Finally, the original template is selectively etched away to leave a solid crystalline skeleton formed at the interfaces of the colloidal template. [ 19 ] Fabrication of monolayer hollow inorganic silica and inorganic hybrid spheres is also reported through the colloid templating route by using electrostatic layer-by-layer self-assembly of silica nanoparticle– polymer multilayers, followed by removal of the polystyrene latex template. [ 20 ] Similar solution-templating approaches have generated related cage structures of different material compositions including ZrO 2 , [ 21 ] CeO 2, [ 22 ] TiO 2 , [ 23 ] SnO 2 , [ 24 , 25 ]

16 citations

Journal ArticleDOI
TL;DR: In this article, a plane-wave-based transfer matrix method was developed to study the guided modes in curved nanoribbon waveguides, where the problem of a curved structure was transformed into an equivalent one of a straight structure with spatially dependent tensors of dielectric constant and magnetic permeability.
Abstract: The authors develop a plane-wave-based transfer matrix method in curvilinear coordinates to study the guided modes in curved nanoribbon waveguides. The problem of a curved structure is transformed into an equivalent one of a straight structure with spatially dependent tensors of dielectric constant and magnetic permeability. The authors investigate the coupling between the eigenmodes of the straight part and those of the curved part when the waveguide is bent. The authors show that curved sections can result in strong oscillations in the transmission spectrum similar to the recent experimental results of Lawet al. [Science 305, 1269 (2004)].

16 citations

Proceedings ArticleDOI
06 May 2007
TL;DR: In this article, an optoelectronic tweezers device that produces electric fields parallel to the plane of the device is presented, capable of trapping and transporting p-type silicon nanowires at velocities of 20 mum/s.
Abstract: We present a new optoelectronic tweezers device that produces electric fields parallel to the plane of the device. This device is capable of trapping and transporting p-type silicon nanowires at velocities of 20 mum/s.

16 citations


Cited by
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01 May 1993
TL;DR: Comparing the results to the fastest reported vectorized Cray Y-MP and C90 algorithm shows that the current generation of parallel machines is competitive with conventional vector supercomputers even for small problems.
Abstract: Three parallel algorithms for classical molecular dynamics are presented. The first assigns each processor a fixed subset of atoms; the second assigns each a fixed subset of inter-atomic forces to compute; the third assigns each a fixed spatial region. The algorithms are suitable for molecular dynamics models which can be difficult to parallelize efficiently—those with short-range forces where the neighbors of each atom change rapidly. They can be implemented on any distributed-memory parallel machine which allows for message-passing of data between independently executing processors. The algorithms are tested on a standard Lennard-Jones benchmark problem for system sizes ranging from 500 to 100,000,000 atoms on several parallel supercomputers--the nCUBE 2, Intel iPSC/860 and Paragon, and Cray T3D. Comparing the results to the fastest reported vectorized Cray Y-MP and C90 algorithm shows that the current generation of parallel machines is competitive with conventional vector supercomputers even for small problems. For large problems, the spatial algorithm achieves parallel efficiencies of 90% and a 1840-node Intel Paragon performs up to 165 faster than a single Cray C9O processor. Trade-offs between the three algorithms and guidelines for adapting them to more complex molecular dynamics simulations are also discussed.

29,323 citations

28 Jul 2005
TL;DR: PfPMP1)与感染红细胞、树突状组胞以及胎盘的单个或多个受体作用,在黏附及免疫逃避中起关键的作�ly.
Abstract: 抗原变异可使得多种致病微生物易于逃避宿主免疫应答。表达在感染红细胞表面的恶性疟原虫红细胞表面蛋白1(PfPMP1)与感染红细胞、内皮细胞、树突状细胞以及胎盘的单个或多个受体作用,在黏附及免疫逃避中起关键的作用。每个单倍体基因组var基因家族编码约60种成员,通过启动转录不同的var基因变异体为抗原变异提供了分子基础。

18,940 citations

Journal ArticleDOI
TL;DR: This work reviews the historical development of Transition metal dichalcogenides, methods for preparing atomically thin layers, their electronic and optical properties, and prospects for future advances in electronics and optoelectronics.
Abstract: Single-layer metal dichalcogenides are two-dimensional semiconductors that present strong potential for electronic and sensing applications complementary to that of graphene.

13,348 citations

Journal ArticleDOI
TL;DR: The semiconductor ZnO has gained substantial interest in the research community in part because of its large exciton binding energy (60meV) which could lead to lasing action based on exciton recombination even above room temperature.
Abstract: The semiconductor ZnO has gained substantial interest in the research community in part because of its large exciton binding energy (60meV) which could lead to lasing action based on exciton recombination even above room temperature. Even though research focusing on ZnO goes back many decades, the renewed interest is fueled by availability of high-quality substrates and reports of p-type conduction and ferromagnetic behavior when doped with transitions metals, both of which remain controversial. It is this renewed interest in ZnO which forms the basis of this review. As mentioned already, ZnO is not new to the semiconductor field, with studies of its lattice parameter dating back to 1935 by Bunn [Proc. Phys. Soc. London 47, 836 (1935)], studies of its vibrational properties with Raman scattering in 1966 by Damen et al. [Phys. Rev. 142, 570 (1966)], detailed optical studies in 1954 by Mollwo [Z. Angew. Phys. 6, 257 (1954)], and its growth by chemical-vapor transport in 1970 by Galli and Coker [Appl. Phys. ...

10,260 citations