Browsing by Author "Wang, Chin-Li"

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A fluorene-modified porphyrin for efficient dye-sensitized solar cells
(2012)
Wu, Cheng-Hua
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Pan, Tsung-Yu
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Hong, Shang-Hao
;
Wang, Chin-Li
;
Kuo, Hshin-Hui
Porphyrins bearing a polyaromatic or a heterocyclic group are prepared to study their fundamental and photovoltaic properties. Solar cells sensitized with a fluorene-modified porphyrin outperform other dyes in the series, reaching similar to 90% efficiency of N719 dye.
A strategy to design highly efficient porphyrin sensitizers for dye-sensitized solar cells
(2011)
Chang, Yu-Cheng
;
Wang, Chin-Li
;
Pan, Tsung-Yu
;
Hong, Shang-Hao
;
Lan, Chi-Ming
We designed highly efficient porphyrin sensitizers with two phenyl groups at meso-positions of the macrocycle bearing two ortho-substituted long alkoxyl chains for dye-sensitized solar cells; the ortho-substituted devices exhibit significantly enhanced photovoltaic performances with the best porphyrin, LD14, showing J(SC) = 19.167 mA cm(-2), V(OC) = 0.736 V, FF = 0.711, and overall power conversion efficiency eta = 10.17%.
Co-Sensitization of Zinc and Free-Base Porphyrins with an Organic Dye for Efficient Dye-Sensitized Solar Cells
(2014-12-04)
Wang, Chin-Li
;
Shiu, Jia-Wei
;
Hsiao, Yen-Ni
;
Chao, Pei-Shang
;
Diau, Eric Wei-Guang
Co-sensitization of an efficient zinc porphyrin sensitizer (LD14) with its free-base analogue (H(2)LD14) and an organic dye (AN-3) improves the efficiency of the dye-sensitized solar cells. The superior performance of the co-sensitized system is attributed to complementary absorptions of the three dyes, resulting in panchromatic incident photon-to-current conversion efficiency responses at the expense of only slightly lowered open-circuit voltage.
Enhanced light harvesting with pi-conjugated cyclic aromatic hydrocarbons for porphyrin-sensitized solar cells
(2011-05-01)
Wang, Chin-Li
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Chang, Yu-Cheng
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Lan, Chi-Ming
;
Lo, Chen-Fu
;
Diau, Eric Wei-Guang
Zinc porphyrins in a series bearing a phenylethynyl, naphthalenylethynyl, anthracenylethynyl, phenanthrenylethynyl or pyrenylethynyl substituent, denoted LD1, LD2, LD3a, LD3p or LD4, respectively, were prepared as photosensitizers for dye-sensitized solar cells. The overall efficiencies of the corresponding devices show a trend LD4 > LD3p > LD2 > LD3a > LD1. Significantly, LD4 features J(SC)/mA cm(-2) 19.627, V(OC)/V = 0.711, and FF = 0.721, giving an efficiency eta = 10.06% of power conversion. This value is superior to that of a N719-based solar cell fabricated under similar experimental conditions. The remarkable performance of the LD4 cell is rationalized to be due to the broader and more red-shifted spectral feature that makes the IPCE spectrum to cover broadly across the entire visible region, 400-800 nm.
Enhanced photovoltaic performance with co-sensitization of porphyrin and an organic dye in dye-sensitized solar cells
(2012-04-01)
Lan, Chi-Ming
;
Wu, Hui-Ping
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Pan, Tsung-Yu
;
Chang, Chia-Wei
;
Chao, Wei-Shan
We designed a stepwise approach for co-sensitization of a zinc porphyrin sensitizer (LD12) with a spirally configured organic dye (CD5) for dye-sensitized solar cells. The co-sensitized LD12 + CD5 device showed significantly enhanced V-OC and J(SC) relative to its individual single-dye sensitized devices. Upon optimization, the device made of the LD12 + CD5 system yielded J(SC)/mA cm(-2) = 16.7, V-OC/V = 0.74, FF = 0.73 and eta = 9.0%; this performance is superior to that of either individual device made from LD12 (eta = 7.5%) and CD5 (eta = 5.7%) under the same conditions of fabrication. To understand the effects of the potential shift and charge recombination on the cell performance, we measured charge-extraction (CE) and intensity-modulated photovoltage spectra (IMVS). Upon sensitization with each dye, the TiO2 potentials are similar, but co-sensitization causes the potential to shift down (cathodic shift). Charge recombination was significantly retarded for the co-sensitized system relative to each individual dye-sensitized system, to account for the enhanced V-OC for the former relative to the latter. A test of stability indicates a systematic trend between the LD12 + CD5 and LD12 devices; the performance of the co-sensitized device degraded only similar to 15% and remained stable during the period of 500-1000 h near 295 K.
Enveloping porphyrins for efficient dye-sensitized solar cells
(2012-05-01)
Wang, Chin-Li
;
Lan, Chi-Ming
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Hong, Shang-Hao
;
Wang, Yi-Fen
;
Pan, Tsung-Yu
A series of porphyrins bearing alkoxyl and/or alkyl chains were prepared to investigate the roles of alkoxyl/alkyl chains in the enhanced photovoltaic performance of the dyes. Based on the experimental results and the molecular simulations, we demonstrated that suitable long alkoxyl chains are capable of wrapping the porphyrin core, thus resulting in decreased dye aggregation, elevated excited states and LUMOs, and improved photovoltaic performance.
Highly efficient porphyrin-sensitized solar cells with enhanced light harvesting ability beyond 800 nm and efficiency exceeding 10%
(2014-04-01)
Wang, Chin-Li
;
Hu, Jyun-Yu
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Wu, Cheng-Hua
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Kuo, Hshin-Hui
;
Chang, Yu-Cheng
A new porphyrin sensitizer, LD31, was designed based on a donorp- pi-acceptor structure, in which an ethynyl-anthracenyl moiety was inserted between the dioctylaminophenyl group and the porphyrin core in order to extend the p-conjugation of the dye for improved light-harvesting ability. The device made of LD31 exhibited panchromatic spectral features covering the whole visible region and further extending over 800 nm. When combined with an organic dye (AN-4), the performance of the LD31/AN-4 co-sensitized device attained JSC/ mA cm(-2) = 20.3, VOC/mV = 704, FF = 0.72, and the overall efficiency of power conversion eta=10.3%.
Panchromatic co-sensitization of porphyrin-sensitized solar cells to harvest near-infrared light beyond 900 nm
(2015-01-01)
Shiu, Jia-Wei
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Chang, Yen-Cheng
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Chan, Chien-Yi
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Wu, Hui-Ping
;
Hsu, Hung-Yu
We designed a dimeric porphyrin dye (LDD1) based on an efficient push-pull zinc porphyrin (LD14) with extended pi-conjugation through coupling of two zinc porphine cores via an acetylene bridge at the meso position of the porphyrin to extend the absorption spectrum effectively into the near infrared region. The effect of dye aggregation among porphyrin molecules was significantly suppressed when the LDD1 and LD14 dyes were co-sensitized on a nanocrystalline TiO2 film in a dye-sensitized photovoltaic system. The light-harvesting ability of the device exhibits a panchromatic feature covering a broad spectral region from 400 nmto 900 nm, which results in a short-circuit current density of 21.3 mA cm(-2) and a power conversion efficiency of 10.4% in an iodine-based solar cell.
Porphyrin-Incorporated 2D D-A Polymers with Over 8.5% Polymer Solar Cell Efficiency
(2014-08-13)
Chao, YI-Hsiang
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Jheng, Jyun-Fong
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Wu, Jhong-Sian
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Wu, Kuan-Yi
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Peng, Hsih-Hao
Porphyrin-Incorporated 2D D-A Polymers with Over 8.5% Polymer Solar Cell Efficiency
(2014-08-13)
Chao, YI-Hsiang
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Jheng, Jyun-Fong
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Wu, Jhong-Sian
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Wu, Kuan-Yi
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Peng, Hsih-Hao
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.
Tuning Spectral and Electrochemical Properties of Porphyrin-Sensitized Solar Cells
(2010-07-15)
Lo, Chen-Fu
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Hsu, Shun-Ju
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Wang, Chin-Li
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Cheng, Yi-Hui
;
Lu, Hsueh-Pei
Phenylethynyl-substituted porphyrin (PEI) sensitizers bearing a nitro, cyano, methoxy, or dimethylamino phenylethynyl substituent were prepared to examine the electron-donating or -withdrawing effects of dyes on the photovoltaic performance of the corresponding dye-sensitized solar cells. The overall efficiencies of power conversion of the devices show a systematic trend Me(2)N-PE1 > MeO-PE1 > CN-PE1 > NO(2)-PE1, for which Me(2)N-PE1 has a device performance about 90% of that of a N719-sensitized solar cell under the same experimental conditions. The superior performance of Me(2)N-PE1 is attributed to the effective electron-donating property of the dye that exhibits broadened and red-shifted spectral features. According to frontier orbitals based on DFT calculations, the electrons are effectively injected from the dye to TiO(2) for Me(2)N-PE1 and MeO-PE1 upon excitation, but that driving force reverses for NO(2)-PE1. Electrochemical tests indicate that both LUMO and HOMO levels show a systematic trend Me(2)N-PE1 > MeO-PE1 > CN-PE1 > NO(2)-PE1, consistent with the trend of variation of the short-circuit currents in this series of sensitizers.