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Printing Silver and Luminescent Nanoparticles in
Polymer Matrices for Energy and Security Applications
Authors: Tyler Blumenthal1, Dr. Jon Kellar1, Dr. William Cross1, Dr. P. Stanley May2, Cuikun Lin2, QuocAnh Luu2
1South Dakota School of Mines and Technology, 2University of South Dakota
Energy harvesting devices that are effective and efficient
are key to this era. One particular direction is through use
of luminescent solar concentrators. This research has
focused on the use of direct-write (aerosol jet) printing to
produce the packaging of luminescent solar concentrators
(LSC) and security printed films using upconversion .
Below in Figure 1 is a schematic of a theoretical LSC.
Preliminary work focused on the deposition process of
the metal-enhancing surface and upconversion layer.
Printing upconverters in a PMMA matrix revealed even
dispersion throughout polymer film, leaving no “frosting”
effect as seen with silver. At 1 wt % of upconverting
particles, the films are relatively transparent and show
uniform upconversion as seen in Figure 4.
Solar Radiation
Particles in
The ink contains upconversion nanoparticles dispersed in
a PMMA film. The particles absorb two lower energy
photons and emit a higher energy photon in the visible
region that can be transformed to a current by photovoltaic
material. In this case, the lanthanide doped nanoparticles
absorb 980 nm near-infrared wavelength and emit a green
illumination at 530 nm. Using metal-enhancedfluorescence principles, a noble-metal layer can enhance
and control the luminescence for higher efficiency.
Figure 4
Figure 4: Photographs of upconverters printed in PMMA film onto
glass slides. The upconverted light is refracted to edge of glass.
Power density of laser around 5 W/cm2, spot is 1 cm diameter.
Figure 1
Using direct-write printing, these films can be deposited
homogenously over larger areas to produce LSCs as well
as deposited over stencils to produce thin polymer security
films on document style substrates.
Silver nanoparticles were printed in a PMMA polymer
matrix and produced a film with different characteristics
depending on the angle of incidence. Films can have
transparent or “mirror –like” reflective surfaces, Figure 2.
The ink solutions were composed of toluene and methyl
benzoate in a 9:1 mixture. This solution was found to
control evaporation rate and reduce the “coffee ring” effect
of the polymer to produce homogenous film.
Silver nanoparticles were capped with decanoic acid and
are 4 - 7 nm in diameter. Lanthanide doped nanoparticles
are capped in oleic acid and have a hexagonal shape (60
nm thickness – 120 nm diameter).
Current research has focused on determining specific
amounts of material for optimal printing and illumination.
Polymer beads [poly(methyl methacrylate)] and silver
nanoparticles were each added at 1 wt%, while
upconverting particles (NaYF4:3%Er,17%Yb) are added at
2 wt%.
Printing was performed with Sono-Tek direct write machine
which allows for large scale material deposition. As
material reaches the ultrasonic nozzle orifice, a
controllable flat jet air deflector deposits the material in fan
shaped spray pattern. For security film applications the
material is deposited over a stainless steel stencil with
desired features. Solutions have been printed on bonded
paper, Kapton, and glass slides at room temperature.
Slides were fractured and observed using a scanning
electron microscope (SEM).
Upconversion was observed through he use of Nd:YAG
infrared diode laser at 980 nm wavelength using 1-5 W
through fiber coupling.
Ink printed with both silver
and upconverting particles
gave little to no “frosting”
effect. The oleic acid
capping agent induced
dispersion of the silver
particles, Figure 5. With
particles too close, the
upconversion becomes
quenched and reabsorbed.
Top of PMMA
Glass Slide
Figure 5
Figure 2
SEM imaging revealed that during evaporation the
decanoic-acid capped precipitated away from the polymer.
This effect resulted in an agglomerated sheets of silver on
top each layer deposited, giving a “frosting” effect, Figure
Films and patterned features printed with the upconverting
particles emit a relatively strong green illumination when
under 980 nm diode laser. Both films and features were
successfully printed to glass, Kapton, and high bond paper
substrates. Upconversion is best observed for security
applications with opaque substrates due to refraction.
Figure 2: These images show the same slide at various incidents of
light (a) Transparency of 3 layer film on glass slide. (b) Mirror-like
surface can be seen.
Developed packaging parameters for printing metalenhancing-surfaces using PMMA. “Coffee ring” effect,
build up of polymer at film edge, was negated by solvent
selection. Based on decanoic capping agent on silver
nanoparticles, the nanoparticle dissolution favors the
solvent over the matrix forming the “frosting” effect.
Controlling amount of polymer can determine thickness for
desired film.
With both silver and upconverting nanoparticles evenly
dispersed throughout the polymer, the silver begins to
quench the upconversion. The distance between both
nanoparticles will need to be controlled to prevent
Printed lanthanide doped nanoparticles in PMMA can be
used to fabricate security printed films that are activated by
Near-IR diode lasers. Films are deposited over laser cut
stainless steel stencil at 1 to 2 layers averaging 0.6 to1.2
µm in thickness. Upconverting nanoparticles were added
at 2 wt%. Photographs of upconversion light of various
features from stencil printing are shown below in Figure 6.
 Developing lanthanide doped nanoparticles that can
absorb over a wide range of IR wavelengths
 Printing particles in separate layers as to control
distance between silver an upconverting nanoparticles
 Alter chemistry of lanthanide doped nanoparticles to
illuminate other specific colors of upconversion. Using
stencil based security films, specific features with
various colors would be illuminated under a single
wavelength diode laser.
 Develop printing parameters to “frosting” effect of silver
nanoparticles as to produce capacitors based on altering
conductive and dielectric material composition.
 Test printing of Poly(lauryl methacrylate) for security
printed films for its optimal dissolution of lanthanide
doped nanoparticles in its matrices.
Silver Layers
Figure 3
Figure 3: SEM image of a fractured glass slide with a 3 layer
deposition to show layering of silver. The brighter regions that
resemble frosting layers are the agglomerated silver nanoparticles
(4-7 nm) while the darker region areas are the PMMA matrices.
Figure 6:(a) and (b) represent the
ability print letters using stencil
style deposition of ink. (c)
represents the ability to print
various features at larger scales.
All samples were printed to high
bond paper substrates. Note:
Scale bar printed using OptomecM3D aerosol jet printing.
This material is based upon work supported by the
National Science Foundation/EPSCoR Grant No. 0903804
and by the State of South Dakota.
The authors would also like to thank Dr. Edward Duke, Mr.
Krishnamraju Ankireddy, Mr. James Randle, and Mr.
Jeevan Meruga.

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