As the field of flexible electronics progresses towards heightened complexity and miniaturization, a significant challenge emerges: ensuring precise, robust, and reliable adhesion of functional materials to chemically inert substrates. This challenge is crucial for the continued innovation and performance of electronic devices, where the longevity and effectiveness of adhesion directly influence device reliability. In this context, diazirine-based crosslinkers present an innovative solution by facilitating covalent bonding through a photochemical reaction on inactivated surfaces. Diazirines are small, highly reactive molecules that, upon exposure to ultraviolet light, generate carbenes, an exceptionally reactive species capable of forming strong covalent bonds with a diverse array of polymer surfaces. This is particularly pertinent because these surfaces include materials that are frequently utilized in the architecture of flexible electronics, such as polyimides and other polymers. The incorporation of diazirine crosslinkers as chemical additives not only enhances the adhesion properties of these materials but also allows for unprecedented control over their photopatternability. This advancement enables researchers and manufacturers to fine-tune the properties of polymers in ways that were previously unattainable, thus opening the door for the design of tailored materials that meet specific performance criteria. A key advantage of diazirine chemistry is its compatibility with existing photolithographic processes. This compatibility allows for spatially controlled patterning of functional layers without requiring harsh treatment processes that could otherwise degrade material properties. As a result, this method supports the seamless integration of patterned bonding regions directly into device fabrication workflows. This integration is particularly beneficial for the high-resolution assembly of multilayer circuits, intricate interconnects, and encapsulated components, which are essential in the development of advanced electronic systems. Moreover, the diazirine crosslinking process not only preserves the inherent properties of the patterned polymer but also plays a crucial role in stabilizing the dielectric constant and minimizing dielectric loss. These enhancements are vital for ensuring optimal performance in applications where electrical insulation and low energy loss are critical. In this presentation, we will explore the underlying chemistry of diazirine crosslinkers in depth, illustrate their photopatterning behavior on flexible substrates, and present comprehensive performance data that highlights their efficacy. Our findings substantiate diazirine-based photolithography as a transformative enabler for the next generation of flexible and hybrid electronics, paving the way for advanced applications that push the boundaries of technology in consumer electronics, wearables, and beyond.
