In a step forward for stretchable, wearable technologies, researchers demonstrated a graphene-enabled laser lift-off (GLLO) technique that ensures smooth separation of thin film flexible displays during the manufacturing process. The technique could accelerate development of ultrathin, high-performance devices that fit comfortably against human skin. The GLLO technique, which was developed at Seoul National University of Science and Technology (SeoulTech), takes advantage of the optical, thermal, adhesive, and geometrical properties of graphene to prevent damage to ultrathin displays. A graphene layer improves UV light absorption, distributes heat evenly, and reduces adhesion in the thin film. These factors serve to reduce plastic deformation in the film during the ablation process. Polyimide (PI) films are widely used to make thin film flexible displays, because they offer thermal stability and mechanical flexibility. These films are used for technologies like rollable displays, wearable sensors, and implantable photonic devices. Achieving successful separation of an ultrathin PI film using traditional laser lift-off (LLO) techniques remains a challenge. When the thickness of the film is reduced below 5 μm, it becomes delicate and prone to mechanical deformation during the LLO process. The deformation causes wrinkling and rupturing in the film that can happen in the malfunction of photonic devices. Reducing the thickness of the PI films used in flexible displays enhances the stretchability and mechanical reliability of the device. Next-generation applications, like implantable and wearable photonic health care devices, will require ultrathin film displays to allow conformal contact with soft and curvilinear surfaces. The GLLO technique integrates a layer of chemical vapor deposition (CVD)-grown graphene at the interface between the PI film and the transparent glass carrier. This improves processability and lift-off quality. In addition, the GLLO method mitigates plastic deformation of the PI film and minimizes the carbon residue remaining on the carrier. Also, CVD-grown graphene enables the LLO performance to be programmed by controlling the number of integrated layers. “Graphene’s unique properties, such as its ability to absorb UV light and distribute heat laterally, enable us to lift off thin substrates cleanly, without leaving wrinkles or residues,” professor Sumin Kang, who led the research, said. To demonstrate the effectiveness of the integrated graphene, the researchers compared the process window and lift-off quality of the PI film using conventional LLO and GLLO. They demonstrated the role of graphene layers during the ablation process through experiments and numerical simulations. Using the GLLO method, the researchers were able to separate 2.9-μm-thick PI substrates without any mechanical damage or carbon residue. In contrast, traditional methods left the substrates wrinkled and the glass carriers unusable because of the residue left behind. The team created OLED devices on ultrathin PI substrates and processed the OLEDs using GLLO. The OLEDs retained their electrical and mechanical performance, showing consistent current-density-voltage-luminance properties before and after lift-off. They also withstood extreme deformations, such as folding and twisting, without functional degradation. Additionally, the use of GLLO reduced carbon residue on the glass carrier by 92.8%, enabling the carrier to be reused. Based on the experimental results, the GLLO technique shows promise as a method for manufacturing ultrathin, flexible electronics with improved efficiency and reduced costs. GLLO could be used, for example, to design and manufacture flexible devices that monitor events in real-time, rollable smartphones, or fitness trackers that flex and stretch with the movements of the wearer. “Our method brings us closer to a future where electronic devices are not just flexible, but seamlessly integrated into our clothing and even our skin, enhancing both comfort and functionality,” Kang said. In addition to enabling ultrathin, flexible, high-performance devices for daily use, GLLO could open new possibilities for the use of CVD-grown graphene in laser-based manufacturing applications, such as emerging displays, wafer-level packaging, and energy-harvesting devices. The research team plans further enhancements to the GLLO technique, with a focus on complete residue elimination and enhanced scalability. The research was published in Nature Communications (www.doi.org/10.1038/s41467-024-52661-3).