Interplay Between Microstructure, Defect States, and Mobile Charge Generation in Transition Metal Dichalcogenide Heterojunctions

Jeffrey Blackburn, Dana Sulas-Kern, Hanyu Zhang, Zhaodong Li

Research output: Contribution to journalArticlepeer-review

2 Scopus Citations

Abstract

Two-dimensional transition metal dichalcogenides (2D-TMDCs) have gained attention for their promise in next-generation energy-harvesting and quantum computing technologies, but realizing these technologies requires a greater understanding of TMDC properties that influence their photophysics. To this end, we discuss here the interplay between TMDC microstructure and defects with the charge generation yield, lifetime, and mobility. As a model system, we compare monolayer-only and monolayer-rich MoS2 grown by chemical vapor deposition, and we employ the TMDCs in Type-II charge-separating heterojunctions with semiconducting single-walled carbon nanotubes (s-SWCNTs). Our results suggest longer lifetimes and higher yields of mobile carriers in samples containing a small fraction of defect-rich multilayer islands on predominately monolayer MoS2. Compared to the monolayer-only heterojunctions, the carrier lifetimes increase from 0.73 μs to 4.71 μs, the hole transfer yield increases from 23% to 34%, and the electron transfer yield increases from 39% to 59%. We reach these conclusions using a unique combination of microwave photoconductivity (which probes only mobile carriers) along with transient absorption spectroscopy (which identifies spectral signatures unique to each material and type of photoexcited quasiparticle, but does not probe mobility). Our results highlight the substantial changes in photophysics that can occur from small changes in TMDC microstructure and defect density, where the presence of defects does not necessarily preclude improvements in charge generation.

Original languageAmerican English
Pages (from-to)8188-8198
Number of pages11
JournalNanoscale
Volume13
Issue number17
DOIs
StatePublished - 7 May 2021

Bibliographical note

Publisher Copyright:
© The Royal Society of Chemistry.

NREL Publication Number

  • NREL/JA-5K00-78404

Keywords

  • charge transfer
  • chemical vapor deposition
  • microwave photoconductivity
  • single walled carbon nanotubes
  • solar-photochemistry
  • transient absorption
  • transition metal dichalcogenide

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