(A) study on high fill factor stretchable organic light-emitting diodes with a hidden active area in 3D structure

Abstract

Stretchable organic light-emitting diodes (OLEDs) have gained immense attention as versatile optoelectronic devices due to their exceptional ability to conform to various form factors. However, when these stretchable OLEDs are stretched, a common challenge emerges in the form of reduced geometrical fill factor (FF). The FF, representing the ratio of the active area to the total area, plays a critical role in the performance and applicability of stretchable OLEDs. To address this issue and maximize the potential of stretchable OLEDs, we introduce a novel three-dimensional (3D) architecture. This innovative design leverages a hidden active area, which serves a dual purpose as both an emitting area and an interconnector. The concept revolves around attaching an ultrathin OLED to a 3D rigid island array structure through quadaxial stretching, ensuring precise and deformation-free alignment. What sets this approach apart is the ability of a portion of the ultrathin OLED to remain concealed by 'folding in' between adjacent islands when in the initial, non-stretched state. However, as the device is stretched, this concealed portion gradually unfolds and surfaces to the top. This ingenious engineering design allows our stretchable OLEDs to not only boast an initial FF of nearly 100%, but also to maintain this high FF even after enduring substantial deformation equivalent to a 30% biaxial system strain. This innovation has the potential to significantly expand the applicability of stretchable OLEDs, making them more adaptable for various real-world applications where flexibility and high FF are paramount. By addressing the FF limitation, our 3D architecture paves the way for stretchable OLEDs to reach their full potential, ushering in a new era of stretchable optoelectronics.