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Title: Growth and characterization of Zn 1-x Cd x Te 1-y O y highly mismatched alloys for intermediate band solar cells

Authors:
; ; ; ; ; ; ; ;
Publication Date:
Sponsoring Org.:
USDOE
OSTI Identifier:
1396925
Grant/Contract Number:
AC02-05CH11231; 11303715
Resource Type:
Journal Article: Publisher's Accepted Manuscript
Journal Name:
Solar Energy Materials and Solar Cells
Additional Journal Information:
Journal Volume: 169; Journal Issue: C; Related Information: CHORUS Timestamp: 2017-10-04 15:52:11; Journal ID: ISSN 0927-0248
Publisher:
Elsevier
Country of Publication:
Netherlands
Language:
English

Citation Formats

Tanaka, Tooru, Terasawa, Toshiki, Okano, Yuuki, Tsutsumi, Shuji, Saito, Katsuhiko, Guo, Qixin, Nishio, Mitsuhiro, Yu, Kin Man, and Walukiewicz, Wladek. Growth and characterization of Zn 1-x Cd x Te 1-y O y highly mismatched alloys for intermediate band solar cells. Netherlands: N. p., 2017. Web. doi:10.1016/j.solmat.2017.05.002.
Tanaka, Tooru, Terasawa, Toshiki, Okano, Yuuki, Tsutsumi, Shuji, Saito, Katsuhiko, Guo, Qixin, Nishio, Mitsuhiro, Yu, Kin Man, & Walukiewicz, Wladek. Growth and characterization of Zn 1-x Cd x Te 1-y O y highly mismatched alloys for intermediate band solar cells. Netherlands. doi:10.1016/j.solmat.2017.05.002.
Tanaka, Tooru, Terasawa, Toshiki, Okano, Yuuki, Tsutsumi, Shuji, Saito, Katsuhiko, Guo, Qixin, Nishio, Mitsuhiro, Yu, Kin Man, and Walukiewicz, Wladek. 2017. "Growth and characterization of Zn 1-x Cd x Te 1-y O y highly mismatched alloys for intermediate band solar cells". Netherlands. doi:10.1016/j.solmat.2017.05.002.
@article{osti_1396925,
title = {Growth and characterization of Zn 1-x Cd x Te 1-y O y highly mismatched alloys for intermediate band solar cells},
author = {Tanaka, Tooru and Terasawa, Toshiki and Okano, Yuuki and Tsutsumi, Shuji and Saito, Katsuhiko and Guo, Qixin and Nishio, Mitsuhiro and Yu, Kin Man and Walukiewicz, Wladek},
abstractNote = {},
doi = {10.1016/j.solmat.2017.05.002},
journal = {Solar Energy Materials and Solar Cells},
number = C,
volume = 169,
place = {Netherlands},
year = 2017,
month = 9
}

Journal Article:
Free Publicly Available Full Text
This content will become publicly available on May 5, 2018
Publisher's Accepted Manuscript

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  • It has long been recognized that the introduction of a narrow band of states in a semiconductor band gap could be used to achieve improved power conversion efficiency in semiconductor-based solar cells. The intermediate band would serve as a ''stepping stone'' for photons of different energy to excite electrons from the valence to the conduction band. An important advantage of this design is that it requires formation of only a single p-n junction, which is a crucial simplification in comparison to multijunction solar cells. A detailed balance analysis predicts a limiting efficiency of more than 50% for an optimized, singlemore » intermediate band solar cell. This is higher than the efficiency of an optimized two junction solar cell. Using ion beam implantation and pulsed laser melting we have synthesized Zn{sub 1-y}Mn{sub y}O{sub x}Te{sub 1-x} alloys with x<0.03. These highly mismatched alloys have a unique electronic structure with a narrow oxygen-derived intermediate band. The width and the location of the band is described by the Band Anticrossing model and can be varied by controlling the oxygen content. This provides a unique opportunity to optimize the absorption of solar photons for best solar cell performance. We have carried out systematic studies of the effects of the intermediate band on the optical and electrical properties of Zn{sub 1-y}Mn{sub y}O{sub x}Te{sub 1-x} alloys. We observe an extension of the photovoltaic response towards lower photon energies, which is a clear indication of optical transitions from the valence to the intermediate band.« less
  • Cited by 6
  • Alloys from ZnO and ZnS have been synthesized by radio-frequency magnetron sputtering over the entire alloying range. The ZnO{sub 1−x}S{sub x} films are crystalline for all compositions. The optical absorption edge of these alloys decreases rapidly with small amount of added sulfur (x ∼ 0.02) and continues to red shift to a minimum of 2.6 eV at x = 0.45. At higher sulfur concentrations (x > 0.45), the absorption edge shows a continuous blue shift. The strong reduction in the band gap for O-rich alloys is the result of the upward shift of the valence-band edge with x as observed by x-ray photoelectron spectroscopy. As a result,more » the room temperature bandgap of ZnO{sub 1−x}S{sub x} alloys can be tuned from 3.7 eV to 2.6 eV. The observed large bowing in the composition dependence of the energy bandgap arises from the anticrossing interactions between (1) the valence-band of ZnO and the localized sulfur level at 0.30 eV above the ZnO valence-band maximum for O-rich alloys and (2) the conduction-band of ZnS and the localized oxygen level at 0.20 eV below the ZnS conduction band minimum for the S-rich alloys. The ability to tune the bandgap and knowledge of the location of the valence and conduction-band can be advantageous in applications, such as heterojunction solar cells, where band alignment is crucial.« less
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