Stretchable High-Resolution Multifunctional Displays

Internet of things (IoT) technology urged the development of displays, which serve as fundamental human-machine interfaces by visualizing information for the user, in order to accommodate the expanding demand of electronic systems in daily life. For this reason, multifunctional displays, instantly representing non-visible stimulation as optical information, have been actively investigated to conduct diverse remarkable electronic applications. Sound generating displays, which have only lately been highlighted, are designed as single device without additional circuitry elements, while concurrently satisfying high degrees of deformation for wearable and/or attachable device applications.<br/>Alternative current electroluminescent (ACEL) devices are one of the promising candidates as deformable optoelectronics owing to their simple device construction, facile fabrication, mechanical robustness, stable emission, and exceptional deformability. Among them, thin-film type ACEL devices are constructed with two electrodes sandwiching emissive layer that comprises phosphors and dielectric matrix. Under AC bias, thin-film ACEL device can be operated as both EL device and dielectric actuator speaker, originated from their structural similarity, making them optimal candidates as stretchable multifunctional displays. For practical application, patterning techniques also need to be applied to ACEL device. However, existed patterning methods of ACEL device were constrained to low-resolution EL operation (pattern size &gt; 2 mm) and reduced brightness below the industrial standard (&gt; 100 cd/m²). Hence, it is necessary to develop effective way to achieve high-resolution multicolor patterning of devices.<br/>Herein, we report a stretchable high-resolution multifunctional display that can work both as an input and output device. Silver nanowires (AgNWs) and conductive polymer (PEDOT:PSS) embedded in thermoplastic polyurethane (TPU) are used as stretchable electrodes, and high dielectric constant particles (BaTiO₃)-inorganic electroluminescent phosphors (ZnS:Cu)-polydimethylsiloxane (PDMS) composite is adopted as emissive layer. Through surface engineering of both stamp and the top of emissive layer, transfer printing technique for emissive layer was developed. This technique facilitates the high-resolution and multicolor patterning of emissive layer for stretchable multifunctional displays that can be stably operated under dynamic and static deformation. Owing to clear and high-resolution patterning ability, we suggested the multifunctional displays that can work both as input and output device.