Browsing by Author "Pei, Zingway"

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Au Nanoparticle Light Scattering Enhanced Responsivity in Pentacene Phototransistor for Deep-UV Light Detection
(2015-11-01)
Yuan, Shuo-Huang
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Pei, Zingway
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Lai, Hsin-Cheng
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Chen, Chien-Hsun
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Li, Pei-Wen
In this letter, a pentacene thin-film phototransistor (PTFP) with gold nanoparticles (Au-NPs) decoration in bottom-gate structure was demonstrated. With the Au-NPs, this device is capable of scattering the free-space ultra-violet (UV) irradiation into the pentacene film. Therefore, the PTFP with Au-NPs exhibit 4.5-A/W responsivity with V-GS = 0 V at the wavelength of 240 nm. Meanwhile, an ultimate 32.4-A/W responsivity can be achieved with V-GS = -10 V at the wavelength of 240 nm. Such an excellent spectral response suggests PTFP is capable for used in daily and disposable UV status assessment.
Hole transit in P3HT:PCBM solar cells with embedded gold nanoparticles
(2014-02-01)
Cheng, Cheng-En
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Pei, Zingway
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Hsu, Chia-Chen
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Chang, Chen-Shiung
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Chien, Forest Shih-Sen
The electrical properties of polymer solar cells (PSCs) with gold nanoparticles (AuNPs) embedded in the hole transport layers (Hits) were investigated. The PSCs with AuNP-embedded HTLs exhibited 8%, 9.5%, and 22% enhancement in short-circuit current density, open-circuit voltage, and power conversion efficiency, respectively. The low contact resistance at the active layer/Hit interface resulted in the high collection efficiency and low electron-hole recombination. The downshift of the Fermi energy in AuNP-embedded HTLs lowered the energy barrier and thinned the depletion layer at the active layer/HTL interface, accounting for the enhanced collection efficiency. (C) 2013 Elsevier B.V. All rights reserved.
Influences of thermal annealing on P3HT/PCBM interfacial properties and charge dynamics in polymer solar cells
(2015-12-01)
Cheng, Cheng-En
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Dinelli, Franco
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Yu, Chen-Te
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Shih, Hwa-Wei
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Pei, Zingway
The effects of thermal annealing on the interfacial properties of poly(3-hexylthiophene) (P3HT)/[6,6]-phenyl C-61 butyric acid methyl ester (PCBM) and on the charge dynamics in P3HT: PCBM polymer solar cells (PSCs) are investigated. This study determines that an effective phase separation of the P3HT and PCBM caused by thermal annealing achieves a larger interfacial area for efficient exciton dissociation and a well-defined pn junction with few defect levels at the P3HT/PCBM interface. Additionally, thermal annealing creates a compositional gradient across the P3HT: PCBM films, which enhances the charge transit ability significantly. These improved interfacial properties and efficiency in charge transit ability account for the better power conversion efficiency of P3HT: PCBM PSCs treated with thermal annealing. (C) 2015 The Japan Society of Applied Physics
Thermal and angular dependence of next-generation photovoltaics under indoor lighting
(1970-01-01)
Chen, Chia-Yuan
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Kuo, Ting-Yang
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Huang, Chien-Wu
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Jian, Zih-Hong
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Hsiao, Po-Tsung
Next-generation photovoltaic technologies such as dye-sensitized solar cells, organic thin-film photovoltaics and perovskite solar cells are promising to efficiently harvest ambient light energy. However, more and deeper understanding of their photovoltaic characteristics is essential to create new applications under room light illumination. In this study, for the first time, the difference in temperature coefficients and angular dependence of photovoltaic parameters for the large-area devices are investigated systematically under the compact fluorescent lamp and light-emitting diode light. These emerging photovoltaic devices, compared with the single crystalline silicon solar cells, not only have higher open-circuit voltage (up to approximate 1 V) and better power conversion efficiency (in the range of 9.2% similar to 22.6%) but also exhibit less temperature dependent voltage and output power (< -0.6% degrees C-1), as well as broader angular response (over 75 degrees). The state-of-the-art dye-sensitized and organic thin-film devices also show advantageously positive temperature coefficients of current, and the latter even has positive thermal dependence of fill factor. These features suggest the next-generation photovoltaic devices are more favorable than the conventional crystalline silicon solar cells for real-life indoor applications.
Ultra high-density silicon nanowires for extremely low reflection in visible regime
(2011-10-10)
Pei, Ting-Hang
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Thiyagu, Subramani
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Pei, Zingway
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友訊交大聯合研發中心
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D Link NCTU Joint Res Ctr
We fabricated large-area, vertically aligned silicon nanowire (SiNW) arrays on Si substrates employing catalytic etching on a polystyrene nanosphere template. The density of SiNWs was as high as 10(10)/cm(2), and the bottom radii of SiNWs ranged between 30 and 60 nm. The reflection from the SiNW layer was approximately 0.1% over the spectral range of 300-800nm for SiNWs longer than 750 am. Effective medium theory was applied to explain this extremely low reflection, and it was confirmed that the incident light scatters randomly inside cone-like SiNWs, which lengthens the actual traveling path of light. (C) 2011 American Institute of Physics. [doi10.1063/1.3650266]
UV-treated graphene oxide as anode interfacial layers for P3HT: PCBM solar cells
(2015-07-01)
Cheng, Cheng-En
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Tsai, Cheng-Wei
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Pei, Zingway
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Lin, Tsung-Wu
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Chang, Chen-Shiung
Solution-processable graphene oxide (GO) ultrathin films were introduced as anode interfacial layers (AILs) for polymer solar cells (PSCs). The photovoltaic performance of PSCs containing thermal-and UV-treated GO was comparable to that of PSCs with conventional poly(3,4-ethyledioxythiphene): poly(styrenesulfonate) AILs. UV treatment induced the surface activation of GO; an increase in the work function of UV-treated GO improved the energy band alignment at the GO/poly(3-hexylthiophene) interface, which accounted for the efficient hole collection and photovoltaic performance of PSCs with treated GO.