Design,Fabrication And Properties Of Flexible ACEL Devices

Flexible light-emitting devices are an integral part of future wearable integrated device systems with significant practicalvalue and business prospects.In order to realize the flexible light emitting device,it is necessary to investigatethe selection of the functional materials,the design of the device structure,the fabrication process and so on.In this work,we selected AgNWs as the electrode material,alternating current electroluminescence(ACEL)as the light-emitting system,the top-emission structure as the device structure,and the utilization of the blade coating and dip coating protocolrespectively to fabricate planar and fiber-shapedACEL devices,realizing excellent brightness,flexibility and mechanical stability.In addition,the ACEL fiber with excellent wearability and weavability demonstrates the potential future ACEL cloths.AgNWs have indeed been employed in some flexible and stretchable displays previously.However,in virtually all cases,AgNWs are used either as the top or the bottom electrode,depending on the emission structure of the device.Our design with AgNWs serving as both top and bottom electrodes for one-side illuminating flexible EL devices is a first.In conventional flexible EL devices,one electrode(top or bottom)is made by metal film,e.g.,Ag paste,which tends to crack or delaminate from the substrate during cyclic mechanical bending or rolling,limiting the flexibility of the devices.Thanks to the intrinsic good flexibility and stretch-ability of AgNWs,our ACEL devices with both top and bottom AgNWs electrodes exhibit unprecedented flexibility and mechanical stability,being able to endure a strain as large as 6.5%and to maintain 88.4%luminance after 1000 bending-recovery cycles.In addition,most EL devices adopt a bottom emission structure.Our design of top emission structure together with the AgNWs electrodes led to a high luminance(957 cd/m~2@195 V and 2 kHz),which is competitive with the state of the art in the field as acknowledged by the referee.The advantage of our design,high luminance as well as excellent strain durability and mechanical stability of the resulting device are highlighted in comparison with representative devices from the recent reports.Flexible,lightweight,and wearable devices are currently attracting tremendous interest in the field of advanced electronics.We have designed novel one-dimensional,coaxial-structured,flexible and color ACEL fibers comprising AgNWs-based electrodes,ZnS phosphor layer,and silicone dielectric and encapsulation layers,and fabricated them through an easily operational protocol.The facile all-solution-based dip-coating process enabled scalable production of ultra-long ACEL fibers(>12 cm).The as-prepared ACEL fibers produce uniform,bright and angularly independent luminance as high as 202 cd/m~2(195 V,2kHz).Simultaneously,the ACEL fibers exhibit excellent flexibility and mechanical stability,being capable to maintain~91%of luminance after 500 bending-recovery cycles,as well as mitigated luminance degradation after continuous work in ambient.The ultra-length combined with superb mechanical properties makes the ACEL fibers readily weavable.Equally remarkable,encapsulation with the isolating,hydrophobic,and biocompatible silicone layer further renders the ACEL fibers suitable for wearable applications.Eventually,a proof-of-concept ACEL fabric was demonstrated by weaving the as-prepared ultra-long ACEL fibers,to show the future perspective of directly weaving ACEL fibers into densely arrayed wearable functional cloths with the further development of sophisticated integration and weaving techniques.