Page 18 - MSAM-3-2

Materials Science in Additive Manufacturing Functional materials for AM

electrons return to lower energy states. This process enables optimizing the chemical and physical properties of the
perovskites to emit light at wavelengths different from ink, as well as exploring encapsulation and specialized
the absorbed light, showcasing their potential to produce coating techniques. Such advancements are expected to
diverse and pure colors in lighting and display technologies. enhance the commercial viability of perovskite inkjet
LEDs were fabricated using CsPbBr nanocrystals printing technology. In addition, ongoing studies focusing
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that maintain their crystalline structure and exhibit high on optimizing ink viscosity, surface tension, and chemical
properties are crucial for advancing this field.
PLQY even under high-temperature annealing. A novel
inkjet printing technique utilizing high-boiling decalin 3.4. Piezoelectrics
and octane-mixed solvents was developed. This method
demonstrated a six-fold increase in efficiency compared Piezoelectric technology possesses the capability to
to LEDs fabricated using conventional spin coating. convert mechanical energy, such as vibrations or impacts,
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Perovskite LEDs (PeLEDs) have garnered attention due into electrical energy, and vice versa. The piezoelectric and
to their characteristics, such as solution processing, large- converse piezoelectric effects are mathematically described
area fabrication, and flexibility, which contrast with those by Equations I and II, respectively.
of conventional inorganic LEDs. However, challenges D = dT + ∈ E (Piezoelectric effect) (I)
T
arise when applying blade or slot-die coating to flexible S = s T + dE (Converse piezoelectric effect) (II)
E
substrates. In a separate study, large-area fabrication was
achieved through inkjet printing technology. The fabricated In these equations, D represents electric displacement, d
T
PeLEDs exhibited an external quantum efficiency (EQE) of the piezoelectric charge coefficient, T mechanical stress, ∈
14.3% at an area of 0.04 cm², suggesting the feasibility of permittivity of the material (for T = constant), E electrical
E
future wide-color displays. 98 field, S mechanical strain, and s mechanical compliance
(for E = constant). The piezoelectric charge coefficient,
Inkjet printing capable of precision control was d, varies depending on the material and its orientation,
implemented by adding polyvinylpyrrolidone (PVP) to reflecting the material’s effectiveness in converting
perovskite. This technology is activated by light, exhibiting mechanical energy into electrical energy and vice versa.
a fluorescent effect. The patterns created are composed of This technology is crucial in the development of compact
dot microarrays, exhibiting homogeneity at a macroscopic electronic devices, such as portable gadgets, medical
level and high reproducibility at a microscopic level. In the technologies, and Internet of Things devices. 100,101 It enables
pertinent study, the arrangement of these dots enabled the continuous operation without the need for recharging,
creation of complex images such as barcodes, the logo of thereby gaining recognition as an environmentally friendly
Fuzhou University, and honeybee illustrations. Perovskite material.
exhibits nearly invisible characteristics in ambient
conditions and can be applied to flexible substrates, Piezoelectric materials are categorized into ceramics
indicating its potential for use in anticounterfeiting and polymers. Ceramic materials include lead zirconate
99
labels (Figure 5A). Furthermore, complex-shaped and titanate (PZT)-based compounds, which possess high
102
compositionally diverse perovskite heterostructures piezoelectric constants and ferroelectric properties,
were fabricated using meniscus-guided printing. A study as well as lead-free materials, such as BaTiO , known
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103
demonstrated the capability to program various emission for their environmental friendliness. On the polymer
colors, achieving color mixing and encryption at the single side, materials such as polyvinylidene fluoride (PVDF)
nanopixel level. 91 and P(VDF-TrFE) are prominent, particularly in
wearable technologies, due to their flexibility and ease of
Perovskite printing technology is garnering attention processing. 104,105
for its potential applications in flexible electronics and
wearable devices due to its high material utilization Conventional manufacturing methods for piezoelectric
106-108
efficiency and cost-effectiveness. This technology enables devices, including sintering, etching, and cutting,
direct printing on flexible substrates, offering significant exhibit limitations in creating complex geometries. These
design flexibility and the ability to create precise patterns methods often result in issues such as mechanical stress,
through fine nozzles, making it ideal for producing high- loss of grain structure, reduction in strength, and near-
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resolution displays. However, devices such as PSCs and surface depolarization.
photodetectors face challenges in maintaining long- The introduction of 3D printing technology has
term performance stability due to their sensitivity to addressed these challenges, offering advantages over
environmental factors such as humidity and temperature. traditional manufacturing methods as follows: (i) the
To overcome these challenges, further research emphasizes capability to fabricate complex structures, (ii) precise

Volume 3 Issue 2 (2024) 12 doi: 10.36922/msam.3323