Author
Hsu Cheng Hsu
Other affiliations: Industrial Technology Research Institute, National Chiao Tung University, National Taiwan Normal University ...read more
Bio: Hsu Cheng Hsu is an academic researcher from National Cheng Kung University. The author has contributed to research in topics: Photoluminescence & Lasing threshold. The author has an hindex of 24, co-authored 97 publications receiving 2833 citations. Previous affiliations of Hsu Cheng Hsu include Industrial Technology Research Institute & National Chiao Tung University.
Topics: Photoluminescence, Lasing threshold, Quantum dot, Nanorod, Exciton
Papers published on a yearly basis
Papers
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TL;DR: In this article, size-dependent blue shifts of photoluminescence and absorption spectra revealed the quantum confinement effect and the band gap enlargement was in agreement with the theoretical calculation based on the effective mass model.
451 citations
TL;DR: The replacement of the organic hole transport materials by a p-type metal oxide has the advantages to provide robust device architecture for further development of all-inorganic perovskite-based thin-film solar cells and tandem photovoltaics.
Abstract: In this article, we present a new paradigm for organometallic hybrid perovskite solar cell using NiO inorganic metal oxide nanocrystalline as p-type electrode material and realized the first mesoscopic NiO/perovskite/[6,6]-phenyl C61-butyric acid methyl ester (PC61BM) heterojunction photovoltaic device. The photo-induced transient absorption spectroscopy results verified that the architecture is an effective p-type sensitized junction, which is the first inorganic p-type, metal oxide contact material for perovskite-based solar cell. Power conversion efficiency of 9.51% was achieved under AM 1.5 G illumination, which significantly surpassed the reported conventional p-type dye-sensitized solar cells. The replacement of the organic hole transport materials by a p-type metal oxide has the advantages to provide robust device architecture for further development of all-inorganic perovskite-based thin-film solar cells and tandem photovoltaics.
400 citations
TL;DR: The size dependence of electron-phonon coupling is principally a result of the Frohlich interaction as discussed by the authors, and the coupling strength between electron and longitudinal optical phonon, deduced from the ratio of the second-to-first-order Raman scattering intensity, diminishes with reducing the ZnO QD diameter.
Abstract: ZnO quantum dots (QDs) of controlled sizes have been fabricated by a simple sol-gel method. The blueshift of room-temperature photoluminescence measurement from free exciton transition are observed decreasing with the QD size that is ascribed to the quantum confinement effect. From the resonant Raman scattering, the coupling strength between electron and longitudinal optical phonon, deduced from the ratio of the second- to the first-order Raman scattering intensity, diminishes with reducing the ZnO QD diameter. The size dependence of electron-phonon coupling is principally a result of the Frohlich interaction.
150 citations
TL;DR: From the temperature-dependent photoluminescence spectra, the activation energies of free and bound excitons are deduced and the Raman spectrum reveals the high quality of the ZnO nanowires.
Abstract: ZnO nanowires have been synthesized on porous silicon substrates with different porosities via the vapour–liquid–solid method. The texture coefficient analysed from the XRD spectra indicates that the nanowires are more highly orientated on the appropriate porosity of porous silicon substrate than on the smooth surface of silicon. The Raman spectrum reveals the high quality of the ZnO nanowires. From the temperature-dependent photoluminescence spectra, we deduced the activation energies of free and bound excitons.
115 citations
TL;DR: In this article, the authors reported room-temperature ultraviolet stimulated emission and lasing from optically pumped high-quality ZnO nanowires and attributed the mechanism of laser emission to coherent multiple scattering among the random-growth oriented nanowsires.
Abstract: We report room-temperature ultraviolet stimulated emission and lasing from optically pumped high-quality ZnO nanowires. Emission due to the exciton-exciton scattering process shows apparent stimulated-emission behavior. Several sharp peaks associated with random laser action are seen under high pumping intensity. The mechanism of laser emission is attributed to coherent multiple scattering among the random-growth oriented nanowires. The characteristic cavity length is determined by the Fourier transform of the lasing spectrum.
112 citations
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TL;DR: In this paper, the authors used the Williamson-Hall analysis and size-strain plot method to study the individual contributions of crystallite sizes and lattice strain on the peak broadening of ZnO-NPs.
1,784 citations
TL;DR: A review of current research on the optical properties of ZnO nanostructures and results of nonlinear optical studies, such as second-harmonic generation, are presented.
Abstract: We present a review of current research on the optical properties of ZnO nanostructures. We provide a brief introduction to different fabrication methods for various ZnO nanostructures and some general guidelines on how fabrication parameters (temperature, vapor-phase versus solution-phase deposition, etc.) affect their properties. A detailed discussion of photoluminescence, both in the UV region and in the visible spectral range, is provided. In addition, different gain (excitonic versus electron hole plasma) and feedback (random lasing versus individual nanostructures functioning as Fabry-Perot resonators) mechanisms for achieving stimulated emission are described. The factors affecting the achievement of stimulated emission are discussed, and the results of time-resolved studies of stimulated emission are summarized. Then, results of nonlinear optical studies, such as second-harmonic generation, are presented. Optical properties of doped ZnO nanostructures are also discussed, along with a concluding outlook for research into the optical properties of ZnO.
1,746 citations
TL;DR: It is argued that evidence for novel size-dependent properties alone, rather than particle size, should be the primary criterion in any definition of nanoparticles when making decisions about their regulation for environmental, health and safety reasons.
Abstract: The regulation of engineered nanoparticles requires a widely agreed definition of such particles. Nanoparticles are routinely defined as particles with sizes between about 1 and 100 nm that show properties that are not found in bulk samples of the same material. Here we argue that evidence for novel size-dependent properties alone, rather than particle size, should be the primary criterion in any definition of nanoparticles when making decisions about their regulation for environmental, health and safety reasons. We review the size-dependent properties of a variety of inorganic nanoparticles and find that particles larger than about 30 nm do not in general show properties that would require regulatory scrutiny beyond that required for their bulk counterparts.
1,656 citations
TL;DR: In this paper, the opto-electronic properties of perovskite materials and recent progresses in perovsite solar cells are described, and comments on the issues to current and future challenges are mentioned.
1,426 citations
01 Jan 1958
TL;DR: In this article, it was shown that the ordinary semiclassical theory of the absorption of light by exciton states is not completely satisfactory (in contrast to the case of absorption due to interband transitions).
Abstract: It is shown that the ordinary semiclassical theory of the absorption of light by exciton states is not completely satisfactory (in contrast to the case of absorption due to interband transitions). A more complete theory is developed. It is shown that excitons are approximate bosons, and, in interaction with the electromagnetic field, the exciton field plays the role of the classical polarization field. The eigenstates of the system of crystal and radiation field are mixtures of photons and excitons. The ordinary one-quantum optical lifetime of an excitation is infinite. Absorption occurs only when "three-body" processes are introduced. The theory includes "local field" effects, leading to the Lorentz local field correction when it is applicable. A Smakula equation for the oscillator strength in terms of the integrated absorption constant is derived.
1,238 citations