Solar and Photovoltaic Engineering Research Center

Saudi Arabia

Solar and Photovoltaic Engineering Research Center

Saudi Arabia
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Chiang W.-Y.,National Chiao Tung University | Usman A.,National Chiao Tung University | Usman A.,Solar and Photovoltaic Engineering Research Center | Masuhara H.,National Chiao Tung University
Journal of Physical Chemistry C | Year: 2013

We demonstrate that laser pulse duration, which determines its impulsive peak power, is an effective parameter to control the number of optically trapped dielectric nanoparticles, their ejections along the directions perpendicular to polarization vector, and their migration distances from the trapping site. This ability to controllably confine and eject the nanoparticle is explained by pulse width-dependent optical forces exerted on nanoparticles in the trapping site and ratio between the repulsive and attractive forces. We also show that the directional ejections occur only when the number of nanoparticles confined in the trapping site exceeds a definite threshold. We interpret our data by considering the formation of transient assembly of the optically confined nanoparticles, partial ejection of the assembly, and subsequent filling of the trapping site. The understanding of optical trapping and directional ejections by ultrashort laser pulses paves the way to optically controlled manipulation and sorting of nanoparticles. © 2013 American Chemical Society.


Eid J.,Solar and Photovoltaic Engineering Research Center | Liang H.,Intermolecular Inc. | Gereige I.,Solar and Photovoltaic Engineering Research Center | Lee S.,Intermolecular Inc. | Van Duren J.,Intermolecular Inc.
Progress in Photovoltaics: Research and Applications | Year: 2015

We report on a sodium fluoride (NaF) thickness variation study for the H2Se batch furnace selenization of sputtered Cu(In,Ga) films in a wide range of Cu(In,Ga) film compositions to form Cu(In,Ga)Se2 (CIGSe) films and solar cells. Literature review indicates lack of consensus on the mechanisms involved in Na altering CIGSe film properties. In this work, for sputtered and batch-selenized CIGSe, NaF addition results in reduced gallium content and an increase in grain size for the top portion of the CIGSe film, as observed by scanning electron microscopy and secondary ion mass spectrometry. The addition of up to 20 nm of NaF resulted in an improvement in all relevant device parameters: open-circuit voltage, short-circuit current, and fill factor. The best results were found for 15 nm NaF addition, resulting in solar cells with 16.0% active-area efficiency (without anti-reflective coating) at open-circuit voltage (VOC) of 674mV. Copyright © 2013 John Wiley & Sons, Ltd.


Yuan Z.,Soochow University of China | Wu Z.,Soochow University of China | Bai S.,Solar and Photovoltaic Engineering Research Center | Cui W.,Soochow University of China | And 3 more authors.
Organic Electronics: physics, materials, applications | Year: 2015

Abstract Layered bismuth selenide (L-Bi2Se3) nanoplates were implemented as hole transporting layers (HTLs) for inverted organic solar cells. Device based on L-Bi2Se3 showed increasing power conversion efficiency (PCE) during ambient condition storage process. A PCE of 4.37% was finally obtained after 5 days storage, which outperformed the ones with evaporated-MoO3 using poly(3-hexylthiophene) (P3HT) as donor material and [6,6]-phenyl-C61-butyric acid methyl ester (PC61BM) as acceptor. The improved device efficiency can be attributed to the high conductivity and increasing work function of L-Bi2Se3. The work function of L-Bi2Se3 increased with the storage time in ambient condition due to the oxygen atom doping. Ultraviolet photoelectron spectroscopy and high resolution X-ray photoelectron spectroscopy were conducted to verify the increased work function, which originated from the p-type doping process. The device based on L-Bi2Se3 exhibited excellent stability in ambient condition up to 4 months, which was much improved compared to the device based on traditional HTLs. © 2015 Elsevier B.V.


Yang X.,Arizona State University | Wu F.-I.,National Tsing Hua University | Haverinen H.,University of Oulu | Li J.,Arizona State University | And 3 more authors.
Applied Physics Letters | Year: 2011

We report efficient organic light-emitting devices having a platinum-complex emissive layer with the peak external quantum efficiency of 17.5% and power efficiency of 45 lm W-1. Variation in the device performance with platinum-complex layer thickness can be attributed to the interplay between carrier recombination and intermolecular interactions in the layer. Efficient white devices using double platinum-complex layers show the external quantum efficiency of 10%, the Commission Internationale d'Énclairage coordinates of (0.42, 0.41), and color rendering index of 84 at 1000 cd m-2. © 2011 American Institute of Physics.


Pietroy D.,CNRS Laboratory for Microelectronics Technolgy | Gereige I.,Solar and Photovoltaic Engineering Research Center | Gourgon C.,CNRS Laboratory for Microelectronics Technolgy
Microelectronic Engineering | Year: 2013

Transmission scatterometry is studied as a characterization tool for gratings nanoimprinted in a resist layer spincoated on the top of a transparent substrate. In this case, the larger part of the incident signal is transmitted which can make the reflection analysis harder. Although the backward reflections in the substrate induce an error which is difficult to correct, results are shown to be in good agreement with SEM measurements and reflection mode scatteromerty. © 2013 Elsevier B.V. All rights reserved.


Gereige I.,Solar and Photovoltaic Engineering Research Center | Pietroy D.,CNRS Laboratory for Microelectronics Technolgy | Eid J.,Solar and Photovoltaic Engineering Research Center | Gourgon C.,CNRS Laboratory for Microelectronics Technolgy
Microelectronic Engineering | Year: 2013

In this paper, we report on the characterization of biperiodic imprinted structures using a non-destructive optical technique commonly called scatterometry. The nanostructures consist of periodic arrays of square and circular dots which were imprinted in a thermoplastic polymer by thermal nanoimprint lithography. Optical measurements were performed using spectroscopic ellipsometry in the spectral region of 1.5-4 eV. The geometrical profiles of the imprinted structures were reconstructed using the Rigorous Coupled-Wave Analysis (RCWA) to model the diffraction phenomena by periodic gratings. The technique was also adapted for large scale evaluation of the imprint process. Uniqueness of the solution was examined by analyzing the diffraction of the structure at different experimental conditions, for instance at various angles of incidence. © 2013 Elsevier B.V. All rights reserved.

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