Effect of high-energy electron beam irradiation on the properties of ZnO thin films prepared by magnetron sputtering A comparative analysis of deep level emission in ZnO layers deposited by various methods ZnO nanowire NW growth mechanism was investigated in a nonvapor and noncatalytic approach for the controlled NW synthesis in a second time scale. The experimental results showed what ZnO NW growth was determined by migration of zinc interstitials and vacancies in a ZnO layer, which should be also considered in other synthesis techniques and mechanisms. The mechanism of the ZnO NW growth was explained as due to the advantageous diffusion through grain boundaries in ZnO layer and crystal defects in NWs. Additionally, on the basis of photoluminescence measurements, a feasible application of as-produced wires for optoelectronic devices was demonstrated.

Deformable full-colour light-emitting diodes with ultrafine pixels are essential for wearable electronics, which requires the conformal integration on curvilinear surface as well as retina-like high-definition displays. However, there are remaining challenges in terms of polychromatic configuration, electroluminescence efficiency and/or multidirectional deformability. Here we present ultra-thin, wearable colloidal quantum dot light-emitting diode arrays utilizing the intaglio transfer printing technique, which allows the alignment of red–green–blue pixels with high resolutions up to 2,460 pixels per inch. This technique is readily scalable and adaptable for low-voltage-driven pixelated white quantum dot light-emitting diodes and electronic tattoos, showing the best electroluminescence performance (14,000 cd m−2 at 7 V) among the wearable light-emitting diodes reported up to date. The device performance is stable on flat, curved and convoluted surfaces under mechanical deformations such as bending, crumpling and wrinkling. These deformable device arrays highlight new possibilities for integrating high-definition full-colour displays in wearable electronics.

Recent technological advances in nanomaterials have driven the development of high-performance light-emitting devices with flexible and stretchable form factors. Deformability in such devices is mainly achieved by replacing the rigid materials in the device components with flexible nanomaterials and their assemblies (e.g., carbon nanotubes, silver nanowires, graphene, and quantum dots) or with intrinsically soft materials and their composites (e.g., polymers and elastomers). Downscaling the dimensions of the functional materials to the nanometer range dramatically decreases their flexural rigidity, and production of polymer/elastomer composites with functional nanomaterials provides light-emitting devices with flexibility and stretchability. Furthermore, monolithic integration of these light-emitting devices with deformable sensors furnishes the resulting display with various smart functions such as force/capacitive touch-based data input, personalized health monitoring, and interactive human-machine interfacing. These ultrathin, lightweight, and deformable smart optoelectronic devices have attracted widespread interest from materials scientists and device engineers. Here, a comprehensive review of recent progress concerning these flexible and stretchable smart displays is presented with a focus on materials development, fabrication techniques, and device designs. Brief overviews of an integrated system of advanced smart displays and cutting-edge wearable sensors are also presented, and, to conclude, a discussion of the future research outlook is given.

exhibits high potential for a wide range of bio-electronics applications that need to be mechanically deformable, such as personalized healthcare systems, [4,5] wearable smart displays, [6][7][8] and implantable prosthetic devices, [9][10][11] while rigid electronics suffer in fully exhibiting their original performance on such applications.The evolution of stretchable electronics was initially driven by advancements in human bio-signal sensing technologies. A variety of stretchable sensors, such as thermal sensors (e.g., temperature, thermal conductivity), [12][13][14] mechanical sensors (e.g., strain, pressure), [15][16][17] optical sensors (e.g., pulse oximetry, photoplethysmogram (PPG)), [6,18,19] electrophysiology (EP) sensors (e.g., electroencephalogram (EEG), electrocardiogram (ECG)), [20][21][22] and biochemical sensors (e.g., glucose, pH), [23][24][25][26] have been developed aided by unconventional electronic materials and device designs. As these stretchable sensors tend to mimic the unique mechanical properties of soft and deformable human tissues, stable conformal contact between these sensors and human skin and/or internal organs is achievable. This unique biotic/abiotic interfacing results in outstanding sensing accuracies and extraordinary signal-to-noise ratios that surpass the performance of rigid bio-sensing devices.As stretchable sensor technology has evolved, there has been a growing demand for other stretchable electronic components capable of processing signals retrieved from stretchable sensors. The stretchable electronics research direction has therefore moved toward building stretchable integrated electronic systems that consist not only of stretchable sensory components, but also of other advanced stretchable electronic components for signal processing, feedback actuation, real-time display, wireless communication, and power supply. [27,28] Considerable research effort has been devoted by material scientists and device engineers to achieving fully integrated stretchable electronic systems.The research approaches to such stretchable sensors, additional electronic components, and fully integrated systems are largely categorized by two strategies, namely the "structurebased" and "material-based" approaches. For the structurebased approach, technologies for conventional electronics are utilized to build stretchable electronic systems in which the superb performance of conventional electronics can be fully Stretchable electronics are mechanically compatible with a variety of objects, especially with the soft curvilinear contours of the human body, enabling human-friendly electronics applications that could not be achieved with conventional rigid electronics. Therefore, extensive research effort has been devoted to the development of stretchable electronics, from research on materials and unit device, to fully integrated systems. In particular, material-processing technologies that encompass the synthesis, assembly, and patterning of intrinsically stretchable electronic materials have been ac...