Matching Items (18)
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ContributorsLiu, Shi (Author) / Zhao, Xin-Hao (Author) / Campbell, Calli M. (Author) / DiNezza, Michael J. (Author) / Zhao, Yuan (Author) / Zhang, Yong-Hang (Author)
Created2015
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ContributorsZhao, Xin-Hao (Author) / DiNezza, Michael J. (Author) / Liu, Shi (Author) / Campbell, Calli M. (Author) / Zhao, Yuan (Author) / Zhang, Yong-Hang (Author)
Created2014
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ContributorsZhao, Xin-Hao (Author) / DiNezza, Michael J. (Author) / Liu, Shi (Author) / Lin, Su (Author) / Zhao, Yuan (Author) / Zhang, Yong-Hang (Author)
Created2014
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ContributorsHild, Konstanze (Author) / Sweeney, S. J. (Author) / Wright, S. (Author) / Lock, D. A. (Author) / Jin, S. R. (Author) / Marko, I. P. (Author) / Johnson, Shane R. (Author) / Chaparro, S. A. (Author) / Yu, S.-Q. (Author) / Zhang, Yong-Hang (Author)
Created2006
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ContributorsBückers, C. (Author) / Blume, G (Author) / Thränhardt, A. (Author) / Schlichenmaier, C. (Author) / Klar, P. J. (Author) / Weiser, G. (Author) / Koch, S. W. (Author) / Hader, J. (Author) / Moloney, J. V. (Author) / Hosea, T. J. C. (Author) / Sweeney, S. J. (Author) / Wang, J.-B. (Author) / Johnson, Shane R. (Author) / Zhang, Yong-Hang (Author)
Created2007
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ContributorsLiu, Xinyu (Author) / Smith, D. J. (Author) / Fan, Jin (Author) / Zhang, Yong-Hang (Author) / Cao, Helin (Author) / Chen, Yong P. (Author) / Leiner, J. (Author) / Kirby, B. J. (Author) / Dobrowolska, Malgorzata (Author) / Furdyna, Jacek K. (Author)
Created2011
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ContributorsFan, Jin (Author) / Ouyang, Lu (Author) / Liu, Xinyu (Author) / Ding, Ding (Author) / Furdyna, Jacek K. (Author) / Smith, David J. (Author) / Zhang, Yong-Hang (Author)
Created2012
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Description
Cadmium Telluride (CdTe) possesses preferable optical properties for photovoltaic (PV) applications: a near optimum bandgap of 1.5 eV, and a high absorption coefficient of over 15,000 cm-1 at the band edge. The detailed-balance limiting efficiency is 32.1% with an open-circuit voltage (Voc) of 1.23 V under the AM1.5G spectrum. The record polycrystalline CdTe thin-film cell efficiency has reached 22.1%, with excellent short-circuit current densities (Jsc) and fill-factors (FF). However, the Voc (~900 mV) is still far below the theoretical value, due to the large non-radiative recombination in the polycrystalline CdTe absorber, and the low-level p-type doping.
Monocrystalline CdTe/MgCdTe double-heterostructures (DHs) grown on lattice-matched InSb substrates have demonstrated impressively long carrier lifetimes in both unintentionally doped and Indium-doped n-type CdTe samples. The non-radiative recombination inside of, and at the interfaces of the CdTe absorbers in CdTe/MgCdTe DH samples has been significantly reduced due to the use of lattice-matched InSb substrates, and the excellent passivation provided by the MgCdTe barrier layers. The external luminescent quantum efficiency (η_ext) of n-type CdTe/MgCdTe DHs is up to 3.1%, observed from a 1-µm-thick CdTe/MgCdTe DH doped at 1017 cm-3. The 3.1% η_ext corresponds to an internal luminescent quantum efficiency (η_int) of 91%. Such a high η_ext gives an implied Voc, or quasi-Fermi-level splitting, of 1.13 V.
To obtain actual Voc, the quasi-Fermi-level splitting should be extracted to outside the circuit using a hole-selective contact layer. However, CdTe is difficult to be doped p-type, making it challenging to make efficient PN junction CdTe solar cells. With the use of MgCdTe barrier layers, the hole-contact layer can be defective without affecting the voltage. P-type hydrogenated amorphous silicon is an effective hole-selective contact for CdTe solar cells, enabling monocrystalline CdTe/MgCdTe DH solar cells to achieve Voc over 1.1 V, and a maximum active area efficiency of 18.8% (Jsc = 23.3 mA/cm2, Voc = 1.114 V, and FF = 72.3%). The knowledge gained through making the record-efficiency monocrystalline CdTe cell, particularly the n-type doping and the double-heterostructure design, may be transferable to polycrystalline CdTe thin-film cells and improve their competitiveness in the PV industry.
Monocrystalline CdTe/MgCdTe double-heterostructures (DHs) grown on lattice-matched InSb substrates have demonstrated impressively long carrier lifetimes in both unintentionally doped and Indium-doped n-type CdTe samples. The non-radiative recombination inside of, and at the interfaces of the CdTe absorbers in CdTe/MgCdTe DH samples has been significantly reduced due to the use of lattice-matched InSb substrates, and the excellent passivation provided by the MgCdTe barrier layers. The external luminescent quantum efficiency (η_ext) of n-type CdTe/MgCdTe DHs is up to 3.1%, observed from a 1-µm-thick CdTe/MgCdTe DH doped at 1017 cm-3. The 3.1% η_ext corresponds to an internal luminescent quantum efficiency (η_int) of 91%. Such a high η_ext gives an implied Voc, or quasi-Fermi-level splitting, of 1.13 V.
To obtain actual Voc, the quasi-Fermi-level splitting should be extracted to outside the circuit using a hole-selective contact layer. However, CdTe is difficult to be doped p-type, making it challenging to make efficient PN junction CdTe solar cells. With the use of MgCdTe barrier layers, the hole-contact layer can be defective without affecting the voltage. P-type hydrogenated amorphous silicon is an effective hole-selective contact for CdTe solar cells, enabling monocrystalline CdTe/MgCdTe DH solar cells to achieve Voc over 1.1 V, and a maximum active area efficiency of 18.8% (Jsc = 23.3 mA/cm2, Voc = 1.114 V, and FF = 72.3%). The knowledge gained through making the record-efficiency monocrystalline CdTe cell, particularly the n-type doping and the double-heterostructure design, may be transferable to polycrystalline CdTe thin-film cells and improve their competitiveness in the PV industry.
ContributorsZhao, Yuan (Author) / Zhang, Yong-Hang (Thesis advisor) / Bertoni, Mariana (Committee member) / King, Richard (Committee member) / Holman, Zachary (Committee member) / Arizona State University (Publisher)
Created2016