Multiaxial wavy top-emission organic light-emitting diodes on thermally prestrained elastomeric substrates

Abstract

In this work, we report the fabrication process of wavy top-emission organic light-emitting diodes (WOLEDs), which can sustain multiaxial tensile and compressive strains. The devices are fabricated using standard procedures, comprised of the conventional stacks of OLED materials and transfer printing process. Transferring these devices onto thermally prestrained elastomeric substrates and then releasing this strain configure the devices into random, two-dimensional (2D) wavy layouts. The performance of the WOLEDs is analyzed at ±1.5% (strain ratio = 1.16) and ±3% (strain ratio = 2.33) strain with respect to the prestrain value. The fabricated WOLEDs demonstrate good performance in the green light region within ±1.5% and show comparable results even at ±3% tensile and compression strains, which indicates that the fabricated devices can accommodate high strain ratios without inducing significant stresses in the devices. Finite element simulation demonstrates strong coherence with the experimental results and provides a valuable insight into the strain effects on each layer utilized for the device fabrication. Along with that, the neutral plane is generated around the upper region of emission and cathode layers in the devices. A slight blue shift observed by the electroluminescence analysis reveals that luminescence of various colors can be obtained by changing the dimensions of the wavy buckles. This research work can remarkably contribute to the fabrication of multicolored flexible, wearable indicators or curvilinear displays that require the ability not only to bend and stretch, but also to compress in multiple directions with a high strain ratio.