Skip to main page content
Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2019 Apr 23;10(1):1880.
doi: 10.1038/s41467-019-09877-5.

Nanoprinting Organic Molecules at the Quantum Level

Affiliations
Free PMC article

Nanoprinting Organic Molecules at the Quantum Level

Claudio U Hail et al. Nat Commun. .
Free PMC article

Abstract

Organic compounds present a powerful platform for nanotechnological applications. In particular, molecules suitable for optical functionalities such as single photon generation and energy transfer have great promise for complex nanophotonic circuitry due to their large variety of spectral properties, efficient absorption and emission, and ease of synthesis. Optimal integration, however, calls for control over position and orientation of individual molecules. While various methods have been explored for reaching this regime in the past, none satisfies requirements necessary for practical applications. Here, we present direct non-contact electrohydrodynamic nanoprinting of a countable number of photostable and oriented molecules in a nanocrystal host with subwavelength positioning accuracy. We demonstrate the power of our approach by writing arbitrary patterns and controlled coupling of single molecules to the near field of optical nanostructures. Placement precision, high yield and fabrication facility of our method open many doors for the realization of novel nanophotonic devices.

Conflict of interest statement

D.P. is involved with a start-up company (SCRONA) that is attempting to commercialize Electrohydrodynamic Nanoprinting. The remaining authors declare no competing interests.

Figures

Fig. 1
Fig. 1
On-demand electrohydrodynamic printing of dye molecules in a host crystal. a Schematic representation of the printing process of the host material with embedded fluorescent molecules, showing sequentially the process of dropwise deposition, solvent evaporation and crystallization, capturing a single molecule in the crystallized deposit. A detailed schematic of the experimental setup is provided in the Supplementary Fig. 1. The drawing is not to scale. b A schematic representation of a printed array of nanocrystals with embedded fluorescent molecules and illumination direction and polarization. c Atomic force microscopy (AFM) images of four printed pT nanocrystals with varying deposition time tD. The scale bar is 200 nm
Fig. 2
Fig. 2
Optical characterization of the printed dye molecules. a TIRF microscopy image of an ordered array of printed terrylene molecules embedded in pT nanocrystals on a glass substrate and protected from sublimation with a 100 nm thick poly(vinyl alcohol) layer. The scale bar is 2 μm. (see Supplementary Fig. 5 for a schematic of the optical setup). The neighboring nanocrystals can be placed at a distance down to 0.65 μm (see Supplementary Fig. 6). b Fluorescence spectrum of a printed terrylene molecule. c Back focal plane image of a printed terrylene molecule oriented with a polar angle of θ = 16.7 ± 0.5° to the substrate. d Histogram of angular orientation of the molecule embedded in the host crystal with respect to the surface normal direction as shown in the inset. e Histogram of the in-plane radial distribution of molecules around the mean position of the molecules, which ideally corresponds to the printing nozzle axis. The inset shows the measured normalized yield (crosses, normalized to the yield of achieving one molecule per printed spot) for a varying in-plane positioning accuracy compared to a numerical calculation (solid line) of random placement in a hemispherical, printed crystal with the same size. f Histogram of fluorescence count rates of printed single molecules. g Histogram of fluorescence lifetime fitted from continuous wave anti-bunching curves. The mean confidence interval of the fits is ± 0.7 ns. The inset in d is not shown to scale. The fluorescence image of the entire 10 × 10 array from a, and for the extracted data in d, e is shown in Supplementary Fig. 4. f, g are obtained at constant illumination of ~5000 W cm−2
Fig. 3
Fig. 3
Quantum optical characterization of the printed fluorescent molecules. Measured normalized second order correlation function of one (a), two (b), and three (c) dye molecules embedded in a host crystal. Fluorescence time traces and corresponding histograms showing a stable photon count of one printed molecule (d), a one-step bleaching event of two (e), and a two-step bleaching event of three molecules (f). g Measured values of g(2)(0) of photostable molecules with increasing deposition times. h Two molecules with an in-plane separation of 12 ± 5 nm in a single printed nanocrystal. The first panel (left) shows a fluorescence image of both molecules, the second shows the remaining molecule after the other has bleached. The third panel shows the image of the photobleached molecule obtained by subtracting the intensities in panel two from panel one. The scale bar is 200 nm. The rightmost panel shows a schematic of the two molecules in close proximity, based on the position and orientation from the localization analysis (the molecule size is enlarged by approximately 3.5 times for better visibility). See Supplementary Fig. 7 for fluorescence count rates and g(2)(τ) before and after photobleaching. i Probability analysis for printing vs. stochastically placing quantum emitters in specified areas. The expected yields are shown for the example of placing a number of emitters in the vicinity of a 10 μm long waveguide structure as shown in the inset (See Supplementary Note 3 for details on the calculation). Lines are drawn as a guide to the eye. In af pulsed excitation at 6.25 MHz was used and in g and h continuous wave excitation was used
Fig. 4
Fig. 4
On-demand printing of molecules near nanophotonic structures and in arbitrary patterns. a Bright-field (BF) and fluorescence (FL) image of a molecule printed on a single crystalline silver nanowire. The same fluorescence image is shown with the intensities scaled by 12× (FL 12×), where the out-coupled light is clearly visible. The faint fluorescence spot at the left end of the nanowire is due to coupling of the photons to the opposite direction and its lower intensity is attributed to larger propagation losses in that direction. The scale bar is 2 μm. b Simulated coupling efficiency and Purcell factor depending on the location of the molecule with respect to the silver nanowire. The dashed white lines correspond to a coupling efficiency of 30%. Calculations were performed for a vertically oriented dipole inside the printed pT nanocrystal (with its border shown by the solid black lines) and a nanowire of 80 nm diameter. The scale bars are 30 nm. c Bright-field (BF) and fluorescence (FL 5×) images of molecules printed on a TiO2 waveguide with focused laser illumination. Fluorescence images are scaled by 5x in intensity with respect to full scale for better visibility. The red circles mark the location of the printed nanocrystals. The scale bar is 4 μm. d Simulated coupling efficiency depending on the location of the molecule with respect to the TiO2 waveguide. The white dashed line represents the possible location of the molecule based on the measured coupling efficiency of 12%. Calculations were performed for a vertically oriented dipole inside the printed pT nanocrystal (with its border shown by the solid black lines). The scale bar is 100 nm. e Fluorescence image of printed terrylene molecules on a glass substrate composing collectively the molecular structure of terrylene. The dashed, eye-guiding line aids the recognition of the outline of the molecular structure of terrylene. The scale bar is 2 μm

Similar articles

See all similar articles

References

    1. Goban A, et al. Superradiance for atoms trapped along a photonic crystal waveguide. Phys. Rev. Lett. 2015;115:063601. doi: 10.1103/PhysRevLett.115.063601. - DOI - PubMed
    1. Haakh HR, Faez S, Sandoghdar V. Polaritonic normal-mode splitting and light localization in a one-dimensional nanoguide. Phys. Rev. A. 2016;94:053840. doi: 10.1103/PhysRevA.94.053840. - DOI
    1. Kühn S, Håkanson U, Rogobete L, Sandoghdar V. Enhancement of single-molecule fluorescence using a gold nanoparticle as an optical nanoantenna. Phys. Rev. Lett. 2006;97:017402. doi: 10.1103/PhysRevLett.97.017402. - DOI - PubMed
    1. Rivoire K, et al. Lithographic positioning of fluorescent molecules on high-Q photonic crystal cavities. Appl. Phys. Lett. 2009;95:123113. doi: 10.1063/1.3232233. - DOI
    1. Kinkhabwala A, et al. Large single-molecule fluorescence enhancements produced by a bowtie nanoantenna. Nat. Photonics. 2009;3:654–657. doi: 10.1038/nphoton.2009.187. - DOI

Publication types

Feedback