Browsing by Author "Liu, Wei-Lin"

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Effects of Current-Induced Forces on Pt-Benzene-Pt Single-Molecule Junctions
(2014-02-06)
Hsu, Bailey C.
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Amanatidis, Ilias
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Liu, Wei-Lin
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Tseng, Allen
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Chen, Yu-Chang
From first-principles approaches, we investigate the torque exerted by the current-induced forces in a highly asymmetric molecular junction, where the benzene molecule is directly connected to the platinum electrodes. We observe that the curved flow of the current streamline around the tilted molecule can induce a net torque, which tends to rotate the benzene molecule, much like the way a stream of water rotates a waterwheel. The magnitude and direction of the net torque are determined by the detailed current density flowing through the molecular junction. Such an asymmetric molecular junction could offer an experimentally practical system for the exploration of an electrically controllable single-molecule motor. The idea given above is also supported by a simple physical model based on the Landauer-Buttiker formula in the tight-binding framework.
MODELING THE HAZE OF HIGHLY TEXTURED TRANSPARENT CONDUCTING OXIDE
(2010)
Lin, Chienchung
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Liu, Wei-Lin
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Hsieh, Chi-Ying
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光電系統研究所
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Institute of Photonic System
One of the critical factors to improve the efficiency of thin film solar cell is the haze of transparent conducting oxide (TCO), which suffers low values at longer wavelength (> 1 mu m) region. Recently several different highly textured TCO were presented with high haze at near IR region, however, suitable modeling is not established yet. In this paper, we propose a semi-empirical model, which is based on scalar scattering theory, for these highly textured surfaces and achieve good results in numerical fitting.
Oscillatory and sign-alternating behaviors of the Seebeck coefficients in carbon monatomic junctions
(2013-09-24)
Hsu, Bailey C.
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Yao, Hsuan-Te
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Liu, Wei-Lin
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Chen, Yu-Chang
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交大名義發表
In the framework of density functional theory combined with the Lippmann-Schwinger formalism in scattering approaches, we calculate the Seebeck coefficients for carbon atom chains sandwiched between aluminum electrodes from first principles. The most striking feature is that the Seebeck coefficients are length dependent, and can be negative (n type) or positive (p type) for odd- or even-numbered carbon atom chains. Alternating n-type and p-type material properties of carbon atom chains are due to the full-and half-filled pi* -orbital states near the chemical potential.
Scalar scattering model of highly textured transparent conducting oxide
(2011-01-01)
Lin, Chien-Chung
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Liu, Wei-Lin
;
Hsieh, Chi-Ying
;
光電系統研究所
;
Institute of Photonic System
Amorphous silicon solar cell is one of the most well developed solar energy solutions. In order to increase the energy conversion efficiency, light-trapping is necessary to the cell structure. Light trapping can be achieved by a textured transparent conducting oxide (TCO) layer and one of the critical factors of textured TCO is its haze value, which characterizes the scattering capability of the TCO. Recently several highly textured TCOs were presented with high haze at near IR region, where the haze of textured interfaces traditionally suffered from reduced scattering. However, suitable modeling is not established yet. In this work, we use scalar scattering theory and Kirchhoff approximation to solve haze value of complex surfaces analytically. Different from original Rayleigh scattering expression, this model illustrates intricacy between the surface roughness, correlation length, and the separation between different groups of height distributions. The resulting analytical formulation can be applied successfully not only in regular monotonically decaying spectral hazes but also various nonmonotonically shaped ones, meanwhile it retains important physical factors which can be useful for process evaluation. (C) 2011 American Institute of Physics. [doi: 10.1063/1.3530684]