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Page 2 of 32 Keum et al. Soft Sci 2024;4:34 https://dx.doi.org/10.20517/ss.2024.26

INTRODUCTION
Displays are indispensable in our daily lives, playing a critical role in human-machine interaction by
visualizing information as prominent electronic devices. Over the past decade, significant progress has been
made in miniaturization, the development of new luminescent materials, and enhancing display
[1-3]
resolution . Apart from the conventional rigid-type displays based on glass or wafer substrates, stretchable
displays can mechanically deform to accommodate dynamic shapes and withstand mechanical strain
[4,5]
without image distortion . This unique flexibility can open up countless possibilities in various areas such
[7]
[6]
as wearable devices , medical/healthcare monitoring systems , and the next-generation Internet of
Things . According to data obtained from a literature search, a keyword search for “stretchable displays”
[8]
reveals a consistent increase in research activity over the past decade. The number of publications has
grown approximately tenfold, from just 17 in 2014 to 197 in 2023. Notably, there was a sharp increase in the
number of publications between 2018 and 2019 [Figure 1]. In particular, as technology progresses beyond
the development stage, companies have developed various forms of stretchable displays for mass industrial
production. For instance, various stretchable displays have been reported including a 9.1-inch bidirectional
stretchable low-temperature polycrystalline silicon (LTPS)-based active-matrix organic light-emitting diode
(AMOLED) display , a 14.1-inch stretchable 3D AMOLED display for freeform applications , and a full-
[10]
[9]
[11]
color stretchable AMOLED display capable of withstanding both tensile and compressive deformations .
The development of stretchable displays continues to advance through materials engineering, device
[12]
engineering, and manufacturing processes . Key challenges include the achievement of high optical clarity,
electrical conductivity, and mechanical robustness in stretchable substrates and electrodes simultaneously.
Over the past decade, significant progress has been made in designing and manufacturing stretchable
materials, including elastomers, polymers, and nano-material-based conductors, essential for achieving
durable and efficient stretchable displays [12-15] . Exploration in materials engineering for stretchable displays
focuses on identifying and synthesizing materials that exhibit excellent mechanical properties while
maintaining optical clarity and electrical conductivity. Elastomers and polymers play critical roles as
substrates, providing the flexibility necessary to accommodate bending and stretching without
compromising the integrity of integrated electronic components . Simultaneously, conductive materials
[16]
such as carbon nanotubes (CNTs), graphene, and metal nano-particles are investigated for their ability to
maintain electrical pathways during deformation, enabling reliable functionality across various
deformations [14,17] . In complementing these advancements, pattern engineering emerges as a crucial field in
optimizing the performance and durability of stretchable displays. By strategically designing the layout and
architecture of stretchable circuits and electrodes, engineers can mitigate the stress concentrations and
enhance overall mechanical robustness. Techniques such as serpentine designs, fractal patterns, and
hierarchical architectures have shown promising results in dispersing strain and improving the lifespan of
stretchable electronic products [18,19] . Figure 2 schematically summarizes the essential components for
achieving the flexibility in display devices, emphasized in this review. This review aims to provide a
comprehensive overview by focusing on recent research and technological innovations in stretchable
display technology, exploring various approaches to manufacturing stretchable displays, from the basic
components such as luminescent layers to thin-film transistors (TFTs) and integrated circuits, as well as
electrodes and interconnects for accommodating mechanical deformations. Additionally, the review
provides detailed discussions of recent research achievements from material and structural engineering
perspectives, necessary for successful realization of the stretchable displays. Finally, we discuss promising
applications such as wearable physical sensors for electronic skin applications, neuromorphic systems
mimicking biological functions, and next-generation robotics, highlighting the unique advantages and
potential of stretchable displays to expand the boundaries and future development directions for electronic
devices.