Browsing by Author "Wei, Tzu-Chien"

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Environmentally and Mechanically Stable Selenium 1D/2D Hybrid Structures for Broad-Range Photoresponse from Ultraviolet to Infrared Wavelengths
(2018-10-17)
Chen, Yu-Ze
;
You, Yen-Ting
;
Chen, Pin Jung
;
Li, Dapan
;
Su, Teng-Yu
Selenium (Se) is one of the potential candidates as photodetector because of its outstanding properties such as high photoconductivity (similar to 8 x 10(4) S cm(-1)), piezoelectricity, thermoelectricity, and nonlinear optical responses. Solution phase synthesis becomes an efficient way to produce Se, but a contamination issue that could deteriorate the electric characteristic of Se should be taken into account. In this work, a facile, controllable approach of synthesizing Se nanowires (NWs)/films via a plasma-assisted growth process was demonstrated at the low substrate temperature of 100 degrees C. The detailed formation mechanisms of nanowires arrays to thin films at different plasma powers were investigated. Moreover, indium (In) layer was used to enhance the adhesive strength with 50% improvement on a SiO2/Si substrate by mechanical interlocking and surface alloying between Se and In layers, indicating great tolerance for mechanical stress for future wearable devices applications. Furthermore, the direct growth of Se NWs/films on a poly(ethylene terephthalate) substrate was demonstrated, exhibiting a visible to broad infrared detection ranges from 405 to 1555 nm with a high on/off ratio of similar to 700 as well as the fast response time less than 25 ms. In addition, the devices exhibited fascinating stability in the atmosphere over one month.
Performance Characterization of Dye-Sensitized Photovoltaics under Indoor Lighting
(2017-04-20)
Chen, Chia-Yuan
;
Jian, Zih-Hong
;
Huang, Shih-Han
;
Lee, Kun-Mu
;
Kao, Ming-Hsuan
Indoor utilization of emerging photovoltaics is promising; however, efficiency characterization under room lighting is challenging. We report the first round-robin interlaboratory study of performance measurement for dye-sensitized photovoltaics (cells and mini-modules) and one silicon solar cell under a fluorescent dim light. Among 15 research groups, the relative deviation in power conversion efficiency (PCE) of the samples reaches an unprecedented 152%. On the basis of the comprehensive results, the gap between photometry and radiometry measurements and the response of devices to the dim illumination are identified as critical obstacles to the correct PCE. Therefore, we use an illuminometer as a prime standard with a spectroradiometer to quantify the intensity of indoor lighting and adopt the reverse-biased current voltage (I-V) characteristics as an indicator to qualify the I-V sampling time for dye-sensitized photovoltaics. The recommendations can brighten the prospects of emerging photovoltaics for indoor applications.
Pyrazine-incorporating panchromatic sensitizers for dye sensitized solar cells under one sun and dimlight
(2018-07-28)
Desta, Mulu Berhe
;
Vinh, Nguyen Son
;
Kumar, Ch. Pavan
;
Chaurasia, Sumit
;
Wu, Wei-Ti
New D-A--A type (D = electron donor, A = auxiliary acceptor, = -conjugated bridge, and A = electron acceptor/anchor) sensitizers with two bis(alkoxy)phenyl substituents incorporating thieno[3,4-b]pyrazines (TP) or a benzo[3,4-b]pyrazine (BP) entity as the auxiliary acceptor have been synthesized for application in dye-sensitized solar cells (DSSCs). Under 1 sun illumination, the DSSCs fabricated from the two BP dyes with a co-adsorbent have efficiencies of 8.39% and 9.03%, respectively. The latter surpasses that of the standard N719 dye (8.87%). Under dim light conditions MD7 exhibited a power conversion efficiency of 18.95% and 27.17% under 300 lux and 6000 lux irradiance, respectively.