Single-Nanoflake Photo-Electrochemistry Reveals Champion and Spectator Flakes in Exfoliated MoSe2 Films

Elisa Link, Sanjini Nanayakkara, Michael Todt, Allan Isenberg, Justin Sambur

Research output: Contribution to journalArticlepeer-review

23 Scopus Citations

Abstract

Semiconducting transition-metal dichalcogenide (TMD) nanoflake thin films are promising large-area electrodes for photo-electrochemical solar energy conversion applications. However, their energy conversion efficiencies are typically much lower than those of bulk electrodes. It is unclear to what extent this efficiency gap stems from differences among nanoflakes (e.g., area, thickness, and surface structural features). It is also unclear whether individual exfoliated nanoflakes can achieve energy conversion efficiencies similar to those of bulk crystals. Here, we use a single-nanoflake photo-electrochemical approach to show that there are both highly active and completely inactive nanoflakes within a film. For the exfoliated MoSe2 samples studied herein, 7% of nanoflakes are highly active champions, whose photocurrent efficiency exceeds that of the bulk crystal. However, 66% of nanoflakes are inactive spectators, which are mostly responsible for the overall lower photocurrent efficiency compared to the bulk crystal. The photocurrent collection efficiency increases with nanoflake area and decreases more at perimeter edges than at interior step edges. These observations, which are hidden in ensemble-level measurements, reveal the underlying performance issues of exfoliated TMD electrodes for photo-electrochemical energy conversion applications.

Original languageAmerican English
Pages (from-to)6539-6545
Number of pages7
JournalJournal of Physical Chemistry C
Volume122
Issue number12
DOIs
StatePublished - 29 Mar 2018

Bibliographical note

Publisher Copyright:
© 2018 American Chemical Society.

NREL Publication Number

  • NREL/JA-5900-71132

Keywords

  • nanoflake thin films
  • photovoltiacs
  • solar energy conversion
  • solar-photochemistry
  • transition-metal dichalcogenide

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