3D printing of quantum dot embedded polymer nanowires for patterning to triangular-delta and Bayer

Abstract

This contribution presents a method for producing nanoscale color pixels for high-resolution displays using 3D printing of vertically freestanding nanostructures containing red, green, or blue light-emitting quantum dots (QDs). Traditional methods for producing pixels suffer from decreased brightness and pixel density at higher densities due to the reduced volume, but our 3D printing method allows for individual control of brightness by adjusting pixel height in 3D, resulting in a two-fold increase in brightness without changing lateral dimensions. We demonstrate sub-micrometer pixels representing primary colors at a super-high density, enabling image patterns with a pixel resolution of 8,400 ppi and individual modulation of sub-pixels with a possible pixel resolution of 5,600 ppi in triangular-delta and Bayer type designs. The method can be applied to displays, information storage, cryptography, and image sensors. The 3D printing method is a versatile approach for photonic research and has potential for contributing to the development of a range of applications.

Full text

* Corresponding author: jpyo@keri.re.kr
3D printing of quantum dot embedded polymer nanowires for
patterning to triangular-delta and Bayer
Jaeyeon Pyo*
Korea Electrotechnology Research Institute, Electrical Materials Research Division, 51543, Changwon, South Korea
Abstract. This contribution presents a method for producing nanoscale color pixels for high -resolution
displays using 3D printing of vertically freestanding nanostructures containing red, green, or blue light-
emitting quantum dots (QDs). Traditional methods for producing pixels suffer from decreased brightness and
pixel density at higher densities due to the reduced volume, but our 3D printing method allows for individual
control of brightness by adjusting pixel height in 3D, resulting in a two-fold increase in brightness without
changing lateral dimensions. We demonstrate sub-micrometer pixels representing primary colors at a super-
high density, enabling image patterns with a pixel resolution of 8,400 ppi and individual modulation of sub -
pixels with a possible pixel resolution of 5,600 ppi in triangular-delta and Bayer type designs. The method
can be applied to displays, information storage, cryptography, and image sensors. The 3D printing method is
a versatile approach for photonic research and has potential for contributing to the development of a range of
applications.
Introduction
The demand for high-resolution display technologies has
increased rapidly in recent years. Current technologies,
such as liquid crystal displays and organic light-emitting
diodes, have limitations in terms of pixel resolution, color
gamut, and manufacturing cost. In this work, we present
a novel method for producing high-resolution 3D color
nanopixels using quantum dot (QD)-embedded
nanophotonic inks. Our method utilizes femtoliter liquid-
ink-based 3D printing technology, which enables the
production of nanoscale cross-sections with high aspect
ratios and heights of up to 10 µm. The resulting
nanopixels can be used for a wide range of applications,
including displays, information storage, cryptography,
and image sensors.
Methods
We prepared the QD-embedded nanophotonic inks by
dispersing CdSe/ZnS QD powder for red (650 nm), green
(540 nm), and ZnCdSe/ZnS QD powder for blue (480 nm)
in three xylene solvents (concentration: 5 mg/mL). We
then dissolved polystyrene powder in xylene solvent
(concentration: 0.2 wt%) and diluted each QD solution in
three polystyrene solutions, targeting 20 wt% of the QD
to the dissolved polystyrene. After sonication for 5 min,
we obtained the nanophotonic inks.
We used a femtoliter liquid-ink-based 3D printing method
to produce the QD-embedded nanophotonic inks. This
method enabled the production of 3D color pixels with
high-aspect-ratio nanoscale cross-sections, having heights
of up to 10 µm that can be varied to enhance or control
the brightness of the pixels.
To characterize the optical properties of the nanopixels,
we used an LED light with a wavelength of 365 nm and a
continuous-wave laser light with a wavelength of 405 nm
for QD excitation. The LED or laser light was illuminated
from the backside of an objective lens using a dichroic
mirror. PL emissions from the nanopixels were collected
by the same objective lens and split into two parts, one
directed to the color CCD camera for imaging the spatial
distribution of the signal and the other to the spectrometer
used for analyzing the wavelength-dependent intensity.
Fig. 1. 3D printed quantum dot embedded nanowires of dot-
matrix, triangular delta, and Bayer pattern designs with a glass
nanocapillary nozzle for the printing
,04033 (2023)
EPJ Web of Conferences
EOSAM 2023
https://doi.org/10.1051/epjconf/202328704033
287
© The Authors, published by EDP Sciences. This is an open access article distributed under the terms of the Creative
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Results and Discission
We demonstrated the production of R, G, and B light-
emitting nanopixels based on the 3D printing of QD-
embedded nanophotonic inks. The resulting nanopixels
had high aspect ratios and heights of up to 10 µm, which
can be varied to enhance or control the brightness of the
pixels. We demonstrated image patterns with a pixel
resolution of 8,400 ppi and individual modulation of sub-
pixels with a possible pixel resolution of 5,600 ppi in a
triangular delta-type and Bayer pattern designs. The 3D
designs of the nanopixels enabled brightness control but
did not induce significant changes in the spatial resolution.
The presented method has several advantages over
existing technologies. The femtoliter liquid-ink-based 3D
printing method enables the production of 3D color pixels
with high aspect ratios and heights of up to 10 µ m. The
resulting nanopixels can achieve high resolution and color
gamut, making them suitable for use in a wide range of
applications. However, additional efforts are required to
address the challenges associated with industrial-level
manufacturing, such as parallelization with multi-aperture
nozzles and delicate quality control of the substrates and
nozzles. The presented method can realize super-high-
resolution arrays of light-emitting materials for displays,
information storage, cryptography, and image sensors.
Conclusion
To summarize, our study showcases the successful
production of red, green, and blue light-emitting
nanopixels through the 3D printing of QD-embedded
nanophotonic inks. Femtoliter liquid-ink based 3D
printing allowed for the creation of high-aspect-ratio 3D
color pixels with nanoscale cross-sections reaching
heights of up to 10 µm, providing greater control over the
brightness of the pixels. The potential applications for this
method include the creation of super high-resolution
arrays of light-emitting materials for use in displays,
information storage, cryptography, image sensors, and
more. As we move towards device-level implementation,
there may be challenges to overcome, such as addressing
the lead time associated with 3D printing methods. To this
end, we suggest exploring parallelization techniques
utilizing multi-aperture nozzles. Additionally, ensuring
the quality control of the substrates and nozzles will be
necessary for reliable, industrial-level manufacturing.
Enclosure within a transparent polymer matrix may also
help enhance the mechanical stability of the high-aspect-
ratio nanopixels.
References
1. J. Bae, S. Lee, J. Ahn, J. H. Kim, M. Wajahat, W. S.
Chang, S.-Y. Yoon, J. T. Kim, S. K. Seol, and J. Pyo,
ACS Nano, 14, 9, 10993–11001, (2020)
,04033 (2023)
EPJ Web of Conferences
EOSAM 2023
https://doi.org/10.1051/epjconf/202328704033
287
2