Materials and devices for flexible and stretchable photodetectors and light-emitting diodes

Recently,significant efforts have been directed at overcoming the limitations of conventional rigid optoelectronic devices,particularly their poor mechanical stability under bending,folding,and stretching deformations.One of major approaches for rendering optoelectronic devices mechanically deformable is to replace the conventional electronic/optoelectronic materials with functional nanomaterials or organic materials that are intrinsically flexible/stretchable.Further,advanced device designs and unconventional fabrication methods have also contributed to the development of soft optoelectronic devices.Accordingly,new devices such as bio-inspired curved image sensors,wearable light emitting devices,and deformable bio-integrated optoelectronic devices have been developed.In this review,recent progress in the development of soft optoelectronic materials and devices is outlined.First,various materials such as nanomaterials,organic materials,and their hybrids that are suitable for developing deformable photodetectors,are presented.Then,the nanomaterials and organic/polymeric materials that are applicable in deformable light-emitting diodes are described.Finally,representative system-level applications of flexible and stretchable photodetectors and light-emitting diodes are reviewed,and future prospects are discussed.

Nanoscale Materials and Deformable Device Designs for Bioinspired and Biointegrated Electronics

Electronic devices whose structural and functional features are inspired by living creatures have unique performance and unconventional features that are not found in conventional electronic devices.In addition to such bioinspired electronics,with the rise of new fields such as personalized healthcare,mobile electronics,and big-data analysis,biointegrated electronic devices that can collect biomedical information from the human body through various biosensors and deliver appropriate therapeutic feedback stimulations in real time on the spot where immediate treatment is needed have become important.Because body parts and internal organs of living creatures,including humans,have curvilinear shapes and comprise mechanically soft tissues,such bioinspired and biointegrated electronic devices are required to match the soft and deformable features of biological tissues.Such soft and deformable features of electronic devices can be achieved by employing flexible and stretchable materials and unconventional device design techniques.These soft materials and deformable device designs dissipate stress originating from mechanical deformation of the device and thus retard crack generation and/or propagation in the device.Recently,technologies for nanoscale materials have shown a significant level of progress on their material performance and processing technologies.The nanoscale dimension of the electronic materials could achieve extremely small flexural rigidity in comparison to the bulk state of the same materials.Furthermore,techniques to form a well-percolated network of nanomaterials in the elastomeric matrix and to build a pathway for the facile electron and hole transport inside the polymer have induced dramatic performance advances of soft electronic materials,which led to nanocomposites that can accomplish both high mechanical deformability and high electrical performance at the same time.In addition,deformable device designs such as buckled structures and serpentine designs enhance the flexibility and stretchability of the device further.Because of their soft and deformable nature,bioinspired and biointegrated electronic devices could achieve device structures inspired by living creatures and make conformal contact to the target tissue for high-quality measurement of biological signals and real-time feedback treatments.Herein,we introduce recent advances in nanoscale materials and deformable device designs for bioinspired and biointegrated electronics.First,materials with various geometries(e.g.,one-dimensional(1D)nanowires and nanotubes,two-dimensional(2D)nanomembranes and nanoflakes,and three-dimensional(3D)networks of nanomaterials in polymers)are reviewed in terms of their deformable nature.Then,the representative device design strategies required for achieving a soft and deformable form factor(e.g.,buckling method,serpentine design,and kirigami technique)are reviewed.Examples of such state-of-the-art electronic devices are then presented,after which representative system-level applications,including electronic eyes,electronic skin,an electronic ear,wearable electronics,and implantable electronics,are described.Finally,we present a brief future outlook for the field of bioinspired and biointegrated electronics.

Erratum to: Materials and devices for flexible and stretchable photodetectors and light-emitting diodes

Erratum to Nano Research 2021,14(9):2919-2937 https://doi.org/10.1007/s 12274-021-3447-3 The figure caption of Figure 1,instead of Figure 1 Schematic illustration of various nanomaterials and organic materials used in flexible/stretchable photodetectors and light-emitting diodes,and some representative applications.