Browsing by Author "Yeh, Min-Hsin"

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A counter electrode based on hollow spherical particles of polyaniline for a dye-sensitized solar cell
(2012)
Huang, Kuan-Chieh
;
Hu, Chih-Wei
;
Tseng, Chen-Ya
;
Liu, Chen-Yu
;
Yeh, Min-Hsin
Hollow spherical polyaniline (hsPANI) particles are synthesized and deposited on an ITO/glass substrate to prepare a counter electrode (designated as hsPANI-CE) for a dye-sensitized solar cell (DSSC). The structure and crystallization of the hsPANI particles are characterized by using high resolution transmission electron microscopy (HR-TEM), field-emission scanning electron microscopy (FE-SEM), X-ray diffractometry (XRD), X-ray photoelectron spectroscopy (XPS), and Raman spectra. A power-conversion efficiency (h) of 6.84% is obtained for the DSSC with the hsPANI-CE, while it is 6.02% in the case of the DSSC with a CE based on pristine PANI (designated as PANI-CE). Such enhancement is attributed to the hsPANI film having a larger active surface area (A) of 0.191 cm(2), compared to that of the PANI film (A = 0.126 cm(2)), both values being estimated by a rotating disk electrode (RDE). Cyclic voltammetric (CV) curves have evidenced that the electro-catalytic ability of the hsPANI-CE for the reduction of tri-iodide (I-3(-)) ions is higher than that of the PANI-CE. As a reference, the DSSC with a Pt-sputtered CE gives an h of 7.17%. Electrochemical impedance spectroscopic (EIS) spectra are used to substantiate the photovoltaic behaviors. The results suggest that the film consisting of hsPANI particles can be a potential catalytic layer for the replacement of Pt in the CE of a DSSC.
Conducting polymer-based counter electrode for a quantum-dot-sensitized solar cell (QDSSC) with a polysulfide electrolyte
(2011-12-15)
Yeh, Min-Hsin
;
Lee, Chuan-Pei
;
Chou, Chen-Yu
;
Lin, Lu-Yin
;
Wei, Hung-Yu
Conducting polymer materials, i.e., polythiophene (PT), polypyrrole (PPy), and poly(3,4-ethylenedioxythiophene) (PEDOT) were used to prepare counter electrodes (CEs) for quantum-dot-sensitized solar cells (QDSSCs). The QDSSC with PEDOT-CE exhibited the highest solar-to-electricity conversion efficiency (eta) of 1.35%, which is remarkably higher than those of the cells with PT-CE (0.09%) and PPy-CE (0.41%) and very slightly higher than that of the cell with sputtered-gold-CE (1.33%). Electrochemical impedance spectra (EIS) show that this highest conversion efficiency of the PEDOT-based cell is due to higher electrocatalytic activity and reduced charge transfer resistance at the interface of the CE and the electrolyte, compared to those in the case of the cells with other conducting polymers and bare Au. Furthermore, the influences of morphology of the PEDOT film and the charge passed for its electropolymerization on the performance of its QDSSC were also studied. The higher porosity and surface roughness of the PEDOT matrix, with reference to those of other polymers are understood to be the reason for PEDOT to possess higher electrocatalytic activity at its interface with electrolyte. (C) 2011 Elsevier Ltd. All rights reserved.
Large-area blade-coated organic solar cells processed from halogen-free solvent
(2019-12-01)
Chen, Szu-Han
;
Liao, Chung-Hung
;
Chang, Chih-Yu
;
Huang, Kuan-Min
;
Chen, Jen-Yueh
High performance organic solar cells (OSCs) are generally prepared by halogenated solvents, which are detrimental to the environment and human health. The replacement of hazardous halogenated solvents is a priority in the commercialization of solution-processed OSCs. In this study, poly[4,8-bis(5-(2-ethylhexyl)thiophen-2-yl) benzo [1,2-b;4,5-b'] dithiophene-2,6-diyl-alt-(4- (2-ethylhexyl)-3-fluorothieno [3,4-b] thiophene-)-2-carboxylate-2-6-diyl)] (PBDTTT-EFT):[6,6]-phenyl C-71 -butyric acid methyl ester (PC71BM)-based device processed with binary halogen-free solvents (toluene and N-methyl-2-pyrrolidone) is fabricated by blade-coating method. Through the combination of morphological manipulation of active layer and interfacial engineering, the resulting OSCs deliver a promising power conversion efficiency (PCE) up to 11.09%. Importantly, large-area (216 cm(2)) blade-coated bulk-heterojunction OSCs is also demonstrated, and the resulting devices deliver a high PCE up to 5.03%, which is comparable to those of the devices processed with halogenated solvents (PCE = 5.20%). Additionally, the devices processed with halogen-free solvents also exhibit superior stability, maintaining 88% of its initial efficiency after 3960 h of continuous operation. More encouragingly, halogen-free solvents-based manufacturing process can also be performed under ambient conditions, and a moderate PCE of 3.67% is attained for large-area (216 cm(2)) OSCs. To the best of our knowledge, 3.67% represents the highest efficiency ever reported for air-processed large-area OSCs. This work paves the way towards the realization of environmentally-friendly large-area OSCs with high performance and long-term stability.
Study on Oxidation State Dependent Electrocatalytic Ability for I-/I-3(-) Redox Reaction of Reduced Graphene Oxides
(2014-01-01)
Yeh, Min-Hsin
;
Lin, Lu-Yin
;
Huang, Tzu-Yen
;
Chuang, Hui-Min
;
Chu, Chih-Wei
The influence of oxidation states on electrocatalytic abilities for I-3(-) reduction is discussed for reduced graphene oxide (rGO), which is a promising catalyst of counter electrodes for dye-sensitized solar cells (DSSCs). The oxidation states of rGO can be controlled via a photothermal reduction process by varying exposure times. The results reveal that the rGO with lower oxidation state shows smaller charge transfer resistance at the electrode/electrolyte interface and better electrocatalytic ability attributed to higher standard heterogeneous rate constant (k(0)) and reasonable electrochemical surface area (A(e)) for I-3(-) reduction, both are quantitatively determined by a rotating disk electrode system using the Koutecky-Levich equation.