Efficient CdSe nanocrystal diffraction gratings prepared by microcontact molding

R. Clayton Shallcross, Gulraj S. Chawla, F. Saneeha Marikkar, Stephanie Tolbert, Jeffrey Pyun, Neal R. Armstrong

Research output: Contribution to journalArticle

17 Scopus citations

Abstract

We describe the formation of efficient transmission diffraction gratings created from patterned high quality ligand-capped CdSe nanocrystals (NCs), using a facile microcontact molding procedure. Soft polymer replicas of commercially available master gratings were "inked" with solvated NCs and the resulting pattern transferred to a variety of substrates after drying. Large-area (>0.5 cm2), defect free diffraction gratings were prepared with a variety of submicrometer line spacings and feature sizes down to ca. 160 nm. The morphology of the resulting pattern was tuned by controlling the concentration of the NC-based ink. Optimized gratings (1200 g/ mm) showed an increase in transmission diffraction efficiency (DE) with increasing nanocrystal diameter. DE = ca. 15% (488 nm) for 2.5 nm diameter NCs versus DE = ca.25 -30% (488 nm) for 7.3 nm nanocrystals. These increases in DE are ascribed to changes in both the real (n) and imaginary (k) components of the complex index of refraction as NC diameter increases. We demonstrate the ability to in- and out-couple incident laser radiation into internal reflection elements using these stamped NC gratings, including single-mode waveguides, offering a novel application of ordered nanocrystal thin films.

Original languageEnglish (US)
Pages (from-to)3629-3637
Number of pages9
JournalACS Nano
Volume3
Issue number11
DOIs
StatePublished - Nov 24 2009

Keywords

  • Attenuated total reflectance (ATR)
  • CdSe nanocrystals
  • Diffraction grating
  • Internal reflection element (IRE)
  • Microcontact printing
  • Quantum dots (QDs)
  • Refractive index

ASJC Scopus subject areas

  • Materials Science(all)
  • Engineering(all)
  • Physics and Astronomy(all)

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