Efficient Type-II Heterojunction Nanorod Sensitized Solar Cells Realized by Controlled Synthesis of Core/Patchy-Shell Structure and CdS Cosensitization

Sangheon Lee, Joseph C. Flanagan, Jaewook Kim, Alan Jiwan Yun, Byungho Lee, Moonsub Shim, Byungwoo Park

Research output: Contribution to journalArticle

Abstract

Here, we report the successful application of core/patchy-shell CdSe/CdSexTe1-x type-II heterojunction nanorods (HNRs) to realize efficient sensitized solar cells. The core/patchy-shell structure designed to have a large type-II heterointerface without completely shielding the CdSe core significantly improves photovoltaic performance compared to other HNRs with minimal or full-coverage shells. In addition, cosensitization with CdS grown by successive ionic layer adsorption and reaction further improves the power conversion efficiency. One-diode model analysis reveals that the HNRs having exposed CdSe cores and suitably grown CdS result in significant reduction of series resistance. Investigation of the intercorrelation between diode quality parameters, diode saturation current density (J0) and recombination order (β = (ideality factor)-1) reveals that HNRs with open CdSe cores exhibit reduced recombination. These results confirm that the superior performance of core/patchy-shell HNRs results from their fine-tuned structure: photocurrent is increased by the large type-II heterointerface and recombination is effectively suppressed due to the open CdSe core enabling facile electron extraction. An optimized power conversion efficiency of 5.47% (5.89% with modified electrode configuration) is reported, which is unmatched among photovoltaics utilizing anisotropic colloidal heterostructures as light-harvesting materials.

Original languageEnglish (US)
Pages (from-to)19104-19114
Number of pages11
JournalACS Applied Materials and Interfaces
Volume11
Issue number21
DOIs
StatePublished - May 29 2019

Keywords

  • II-VI semiconductor
  • core/shell
  • cosensitization
  • heterojunction nanorod
  • sensitized solar cell

ASJC Scopus subject areas

  • Materials Science(all)

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