Browsing by Author "Hsu, Min-Hsiang"

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Balanced carrier transport in organic solar cells employing embedded indium-tin-oxide nanoelectrodes
(2011-02-14)
Hsu, Min-Hsiang
;
Yu, Peichen
;
Huang, Jen-Hsien
;
Chang, Chia-Hua
;
Wu, Chien-Wei
In this paper, we present evidence of balanced electron and hole transport in polymer-fullerene based solar cells by means of embedded indium-tin-oxide nanoelectrodes. Enabled by a controllable electrochemical deposition, the individual nanoelectrodes are uniformly enclosed by a poly (3,4-ethylenedioxythiophene) hole-conducting layer, allowing a relatively short route for holes to reach the anode and hence increasing the effective hole mobility. Consequently, the power conversion efficiency and photogenerated current are maximized with a deposition condition of 50 mu C, where the ratio of the electron to hole mobility is nearly unity. (C) 2011 American Institute of Physics. [doi:10.1063/1.3556565]
Balanced carrier transport in organic solar cells employing embedded indium-tin-oxide nanoelectrodes (vol 98, 073308, 2011)
(2011-03-14)
Hsu, Min-Hsiang
;
Yu, Peichen
;
Huang, Jen-Hsien
;
Chang, Chia-Hua
;
Wu, Chien-Wei
Combined micro- and nano-scale surface textures for enhanced near-infrared light harvesting in silicon photovoltaics
(2011-03-04)
Chang, Chia-Hua
;
Yu, Peichen
;
Hsu, Min-Hsiang
;
Tseng, Ping-Cheng
;
Chang, Wei-Lun
As silicon photovoltaics evolve towards thin-wafer technologies, efficient optical absorption for the near-infrared wavelengths has become particularly challenging. In this work, we present a solution that employs combined micro- and nano-scale surface textures to increase light harvesting in the near-infrared for crystalline silicon photovoltaics, and discuss the associated antireflection and scattering mechanisms. The surface textures are achieved by uniformly depositing a layer of indium-tin-oxide nanowhiskers on micro-grooved silicon substrates using electron-beam evaporation. The nanowhiskers facilitate optical transmission in the near-infrared by functioning as impedance matching layers with effective refractive indices gradually varying from 1 to 1.3. Materials with such unique refractive index characteristics are not readily available in nature. As a result, the solar cell with combined textures achieves over 90% external quantum efficiencies for a broad wavelength range of 460-980 nm, which is crucial to the development of advanced thin-substrate silicon solar cells.
Embedded indium-tin-oxide nanoelectrodes for efficiency and lifetime enhancement of polymer-based solar cells
(2010-04-12)
Yu, Peichen
;
Chang, Chia-Hua
;
Su, Ming-Shin
;
Hsu, Min-Hsiang
;
Wei, Kung-Hwa
In this paper, distinctive indium-tin-oxide (ITO) nanorods are employed to serve as buried electrodes for polymer-based solar cells. The embedded nanoelectrodes allow three-dimensional conducting pathways for low-mobility holes, offering a highly scaffolded cell architecture in addition to bulk heterojunctions. As a result, the power conversion efficiency of a polymer cell with ITO nanoelectrodes is increased to about 3.4% and 4.4% under one-sun and five-sun illumination conditions, respectively, representing an enhancement factor of up to similar to 10% and 36% compared to a conventional counterpart. Also, the corresponding device lifetime is prolonged twice as much to about 110 min under five-sun illumination.
Enhanced angular characteristics of indium tin oxide nanowhisker-coated silicon solar cells
(2011-05-09)
Chang, Chia-Hua
;
Hsu, Min-Hsiang
;
Tseng, Ping-Chen
;
Yu, Peichen
;
Chang, Wei-Lun
Omnidirectional and broadband light harvesting is critical to photovoltaics due to the sun's movement and its wide spectral range of radiation. In this work, we demonstrate distinctive indium-tin-oxide nanowhiskers that achieve superior angular and spectral characteristics for crystalline silicon solar cells using angle-resolved reflectance spectroscopy. The solar-spectrum weighted reflectance is well below 6% for incident angles of up to 70 and for the wavelength range between 400nm and 1000nm. As a result, the nanowhisker coated solar cell exhibits broadband quantum efficiency characteristics and enhanced short-circuit currents for large angles of incidence. (C) 2011 Optical Society of America
Enhanced Carrier Collection and Light Harvesting of Polymer Solar Cells Using Embedded Indium-Tin-Oxide Nano-Electrods
(2010)
Hsu, Min-Hsiang
;
Chang, Chia-Hau
;
Huang, Jen-Hsien
;
Chu, Chi-Wei
;
Yu, Peichen
Distinctive indium-tin-oxide (ITO) nanorods are employed to serve as buried electrodes for polymer-based solar cells. The embedded nano-electrodes allow three-dimensional conducting pathways for low-mobility holes, offering a highly scaffolded cell architecture in addition to bulk heterojunctions. As a result, the power conversion efficiency and photocurrent of a polymer cell with ITO nano-electrodes demonstrates an enhancement factor of up to similar to 13.1% and 10% respectively, compared to a conventional cell. Furthermore, ITO nanostructures improved optical absorption not only for a wide range of wavelengths, but also at large angles of incidence (AOIs). Hence, devices with 3-D nanoelectrodes exhibited nearly ideal angular response of J(sc), implying great potentials for polymer or other thin-film solar cells.
Enhanced omnidirectional photon coupling via quasi-periodic patterning of indium-tin-oxide for organic thin-film solar cells
(2011-06-01)
Tseng, Ping-Chen
;
Hsu, Min-Hsiang
;
Tsai, Min-An
;
Chu, Chih-Wei
;
Kuo, Hao-Chung
Enhanced optical coupling via an indium tin oxide quasi-periodic structure (ITO-QPS) as the frontal electrode for organic thin film solar cells was demonstrated. The QPS was fabricated via scalable polystyrene colloidal lithography, which effectively coupled the incident light to the photo-active layer through antireflection and light-trapping mechanisms. The cell efficiency was boosted from 2.91% to 3.26%, corresponding to a 12% enhancement after ITO patterning. Moreover, the angle-resolved absorption spectroscopy also confirmed excellent light coupling at large angles of incidence to 45 degrees, particularly in the wavelength range between 540 and 670 nm. The ITO-QPS guarantees broadband and omnidirectional light harvesting and is widely applicable to a variety of thin film solar cells. (C) 2011 Elsevier B.V. All rights reserved.
Novel Indium-Tin-Oxide Nano-Whiskers for Enhanced Transmission of Surface-Textured Silicon Photovoltaic Cells
(2009)
Chang, C. H.
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Hsu, Min-Hsiang
;
Yu, Peichen
;
Kuo, H. C.
;
Chang, W. L.
Conductive Indium-Tin-Oxide (ITO) nano-whiskers were deposited on surface-textured Si solar cells using glancing-angle electron-beam deposition. With different deposited time, the ITO nano-structured layer exhibit tunable thickness, which can be related to the surface reflectance. The optimized nano-whisker surface demonstrates a broadband anti-reflective properties (R<5%), better than the traditional Si(3)N(4) antireflection coating. Current-voltage and quantum efficiency analyses with the measured reflectivity data show enhanced optical transmission in the long wavelength range from 700nm to 1000nm, corresponding to a conversion efficiency improvement from 13.93% to 14.37%.
Performance of chromophore-type electrochromic devices employing indium tin oxide nanorod optical amplification
(2012-03-01)
Huang, Jen-Hsien
;
Hsu, Min-Hsiang
;
Hsiao, Yu-Sheng
;
Chen, Peilin
;
Yu, Peichen
In this study, we used transparent and conductive indium tin oxide (ITO) nanorods, prepared through electron-beam evaporation onto ITO glass substrates, as electrodes for viologen-based electrochromic devices (ECDs). Although the shapes of these ITO nanorods could be controlled simply by manipulating the evaporation time, they always maintained their high optical transmittance. Scanning electron microscopy images revealed that the ITO rods were uniformly distributed on the ITO glass: they had large surface areas for the tethering of electrochromic molecules. As a result, the ITO nanorods functioned as optical amplifiers in the viologen-based ECDs, increasing the color contrast [Delta T (%)] from 38% to 61%. (C) 2011 Elsevier B.V. All rights reserved.
The metal grating design of plasmonic hybrid III-V/Si evanescent lasers
(2013-08-26)
Hsu, Min-Hsiang
;
Lin, Chien-Chung
;
Kuo, Hao-Chung
;
光電系統研究所
;
Institute of Photonic System
A hybrid III-V/silicon laser design with a metal grating layer inserted in between is proposed and numerically studied. The metal grating layer is buried in a silicon ridge waveguide surrounded by silicon dioxide, and its structural parameters such as periodicity, width and depth can be varied for optimization purpose. The plasmonic effect originated from the grating layer can manage optical fields between III-V and silicon layers in hopes of dimension reduction. The substrate is planarized to minimize the bonding failure. A numerical algorithm with various combinations of metal grating and waveguide structural parameters was created and the optimal design with 730 nm grating period and 600 nm of buried waveguide ridge height was obtained by minimizing the corresponding laser threshold. With top AlInGaAs quantum wells and optimized design of hybrid metal/silicon waveguide, a 0.6 mu m(-1) threshold gain can be achieved. (C)2013 Optical Society of America
Three-dimensional indium-tin-oxide electrode, method of fabricating the same, device of fabricating the same, and method of fabricating solar cell comprising the same
(2010-12-09)
Chang, Chia-Hua
;
Yu, Pei-Chen
;
Hsu, Min-Hsiang
;
Wei, Kung-Hwa
;
Su, Ming-Shin
A three-dimensional ITO electrode and the method of fabricating the same are disclosed. The three-dimensional ITO electrode of the present invention has a conductive layer and a plurality of ITO nanorods formed on the conductive layer, wherein the length range of the ITO nanorods can vary from 10 nm to 1500 nm. The best length is about 50 nm-200 nm for organic solar cells. When applied into organic optoelectronic devices such as organic solar cells and organic light-emitting diodes (OLEDs), the three-dimensional structure of the ITO electrode may increase the contact area to the active layer, thus improving the electric current collecting efficiency and uniformity of current spreading (flowing). Also, an evaporator, a solar cell comprising the above three-dimensional ITO electrode, and the method of fabricating the solar cell are disclosed.
Ubiquitous carrier harvesting in organic solar cells with embedded indium-tin-oxide nano-electrodes
(2013-11-01)
Hsu, Min-Hsiang
;
Chen, Po-Han
;
Yu, Peichen
;
Huang, Jen-Hsien
;
Chang, Chia-Hua
Bulk heterojunction in organic solar cells allows adequate interfaces for the dissociation of photo-generated excitons. However, the intermixed donor- and acceptor-like materials do not guarantee successful carrier transport and collections. In this work, we demonstrate ubiquitous carrier harvesting characteristics by using embedded indium-tin-oxide nano-electrodes (NEs) with a conformal electro-polymerized coating of a hole conducting layer. Compared to its planar electrode counterpart, this device exhibits internal quantum efficiency insensitive to the distribution of carrier generation, as determined by angle-resolved absorption spectroscopy and photocurrent characteristics. The ubiquitous carrier harvesting characteristics offer a viable solution to organic thin-film devices fabricated on flexible substrates or operated under diffused ambient light. (C) 2013 Elsevier B.V. All rights reserved.