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

5 Citations (Scopus)

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 - Jan 1 2017

ASJC Scopus subject areas

  • Chemistry(all)
  • Chemical Engineering(all)

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