360° omnidirectional, printable and transparent photodetectors for flexible optoelectronics

Flexible optoelectronics that can be bent, wrapped, and stretched have attracted interest for wearable and mobile applications. In this work, we demonstrate a transparent 360° omnidirectional photodetector (PD) that can be stretched and wrapped around flexible or curved substrates. By embedding interlaced ZnO and Ag nanowires (NWs) in thermoplastic polyurethane via inkjet printing, the device featured > 75% transmittance in the visible region, showing high photoresponsivity and response time (10–30 A/W and 0.8 s, respectively). Moreover, the flexible PD performs well under deformation (only 9% decay in the photocurrent under 60% strain and 8% loss when the device is bent at a radius of 5 mm), which allows it to be readily applied on curved surfaces, such as skin or optical fibers. This study opens the door for the development of flexible optoelectronics that could be implemented in fiber optics, wearable electronics, self-powered systems, bio-signal monitors, and epidermal electronics.360° omnidirectional photodetectors: flexible enough for any applicationInk-jet printed nanowire network-polymer composites enable flexible, transparent photodetectorsthat can be bent, wrapped, and stretched.A collaborative team lead by Jr-Hau He from the Computer, Electrical and Mathematical Sciences and Engineering (CEMSE) Division at King Abdullah University of Science and Technology (KAUST) developed ink-jet printed 360° omnidirectional photodetectors that are fully transparent, stretchable and wrappable. The key to the device’s high degree of functionality is a polyurethane-based composite consisting of a ZnO-Ag interlaced nanowire network. Incorporating the composite into the device structure leads to photodetectors with over 75% transmittance, which enables omnidirectional photodetection with only 78% variation. The device operates under less than 5 mm bending radius and while stretched at over 60% strain, which allows the device to employed in applications such as wearable electronics.