Vertically aligned ZnO/ZnTe core/shell heterostructures on an AZO substrate for improved photovoltaic performance

Songping Luo, Xiaoli He, Heping Shen, Jianbao Li, Xuewen Yin, Dan Oron, Hong Lin

Research output: Contribution to journalArticle

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Abstract

Vertically aligned ZnO/ZnTe core/shell heterostructures on an Al-doped ZnO substrate are developed for non-toxic semiconductor sensitized solar cells. Structural and morphological analysis serves as evidence of the successful synthesis of ZnO nanorods, ZnTe nanocrystals and ZnO/ZnTe heterostructures. The clearly observed quenching of photoluminescence (PL) from the heterostructure indicates efficient charge transfer occurring at the interface of ZnO and ZnTe, due to the type-II energy level alignment constructed by the two. The formation mechanism of the ZnO/ZnTe heterostructure is studied in depth via time-dependent reactions. It was found that the strain between ZnO and ZnTe modifies the band alignment at the interface of the heterostructure in a manner which depends on the growth time. Finally, sensitized solar cells based on the ZnO/ZnTe heterostructures with different ZnTe growth times were fabricated to evaluate the photovoltaic performance. By the careful control of the ZnTe growth time and as a result of the band alignment between ZnO and ZnTe, the power conversion efficiency (PCE) of the vertically aligned ZnO/ZnTe based solar cells could be improved to about 2%, along with a short-circuit photocurrent density of around 7.5 mA cm−2, a record efficiency for ZnO/ZnTe based sensitized solar cells. Notably, for the optimized system the internal quantum efficiency of the ZnO/ZnTe based solar cell approaches 100% in certain wavelengths, implying effective separation of photoexcited free carriers towards either the electrolyte or anode.

Original languageEnglish
Pages (from-to)14837-14845
Number of pages9
JournalRSC Advances
Volume7
Issue number24
DOIs
Publication statusPublished - 2017

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Heterojunctions
Solar cells
Substrates
Nanorods
Photocurrents
Quantum efficiency
Short circuit currents
Nanocrystals
Electron energy levels
Electrolytes
Conversion efficiency
Charge transfer
Quenching
Photoluminescence
Anodes
Semiconductor materials
Wavelength

ASJC Scopus subject areas

  • Chemistry(all)
  • Chemical Engineering(all)

Cite this

Vertically aligned ZnO/ZnTe core/shell heterostructures on an AZO substrate for improved photovoltaic performance. / Luo, Songping; He, Xiaoli; Shen, Heping; Li, Jianbao; Yin, Xuewen; Oron, Dan; Lin, Hong.

In: RSC Advances, Vol. 7, No. 24, 2017, p. 14837-14845.

Research output: Contribution to journalArticle

Luo, Songping ; He, Xiaoli ; Shen, Heping ; Li, Jianbao ; Yin, Xuewen ; Oron, Dan ; Lin, Hong. / Vertically aligned ZnO/ZnTe core/shell heterostructures on an AZO substrate for improved photovoltaic performance. In: RSC Advances. 2017 ; Vol. 7, No. 24. pp. 14837-14845.
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