Flexible micro-light-emitting diodes (f-μLEDs) have been regarded as an attractive light source for the next-generation human–machine interfaces, thanks to their noticeable optoelectronic performances. However, when it comes to their practical utilizations fulfilling industrial standards, there have been unsolved reliability and durability issues of the f-μLEDs, despite previous developments in the high-performance f-μLEDs for various applications. Herein, highly robust flexible μLEDs (f-HμLEDs) with 20 × 20 arrays, which are realized by a siloxane-based organic–inorganic hybrid material (SHM), are reported. The f-HμLEDs are created by combining the f-μLED fabrication process with SHM synthesis procedures (i.e., sol–gel reaction and successive photocuring). The outstanding mechanical, thermal, and environmental stabilities of our f-HμLEDs are confirmed by a host of experimental and theoretical examinations, including a bending fatigue test (105 bending/unbending cycles), a lifetime accelerated stress test (85 °C and 85% relative humidity), and finite element method simulations. Eventually, to demonstrate the potential of our f-HμLEDs for practical applications of flexible displays and/or biomedical devices, their white light emission due to quantum dot-based color conversion of blue light emitted by GaN-based f-HμLEDs is demonstrated, and the biocompatibility of our f-HμLEDs is confirmed via cytotoxicity and cell proliferation tests with muscle, bone, and neuron cell lines. As far as we can tell, this work is the first demonstration of the flexible μLED encapsulation platform based on the SHM, which proved its mechanical, thermal, and environmental stabilities and biocompatibility, enabling us to envisage biomedical and/or flexible display applications using our f-HμLEDs.

In article number 223083, Daniel J. Joe, Han Eol Lee, and colleagues realize a porous wearable patch by stably attaching onto human skin for a week and continuously removing skin by‐products. Based on III‐N compound semiconductors, the wearable patch monitors UV‐A radiation which adversely affects the human skin.

In the upcoming ubiquitous era, wearable/flexible electronics are spotlighted to get various types of numerous information in real time. Several researchers have investigated flexible materials, and developed diverse thin‐film transfer methods. However, there are some limitations of the intrinsic material unstabilities, and low production yield. Here, light‐induced thin‐film transfer methods are reported by using new transfer mechanism of phase transition in sacrificial materials. Lift‐off conditions with high‐energy laser are delicately optimized by theoretical calculations and experiments to minimize mechanical/thermal damages of the upper thin‐film devices. The selected sacrificial materials of GeSbTe (GST) and indium tin oxide (ITO) with the 300 nm thickness are delaminated from a transparent and rigid glass substrate by irradiating the excimer laser to the surface of the sacrificial layer. The laser‐based exfoliation mechanism of GST and ITO films are comprehended by various material surface analyses. Eventually, flexible oxide thin‐film transistors (TFTs) are successfully demonstrated through light‐induced exfoliation process, showing the usability of the developed transfer technique to future practical applications.

UV radiation is considered indispensable from the hygienic, medical, aesthetic, and industrial perspectives. Among the various types of UV radiation, UV‐A (with a wavelength of 315–400 nm) has a significant influence because it adversely affects human skin, leading to damage such as blemishes, freckles, and wrinkles. Although various photosensors are developed for monitoring UV‐A radiation in real time, these devices have critical issues, such as inefficient fabrication processes, insufficient photoresponsivity, and incompatibility with long‐term wearable applications. Here, the authors report on a wearable UV‐detecting patch targeted for long‐term use in the medical and clinical fields. A wearable UV sensor is fabricated by integrating optimized InGaN/GaN microphotodetectors (µPDs) in a 3D porous patch. The optical and electrical properties of the device are intensively investigated under various types of optical radiation and input electrical power and show high photoresponsivity (2.82 A W−1) and excellent external quantum efficiency (897.63%). Long‐term real‐time UV radiation monitoring using the wearable µPDs is demonstrated; moreover, the by‐products can be efficiently removed from human skin surfaces.