Stretchable and flexible electronic devices require both structural and active optoelectronic materials that are compliant and able to withstand mechanical deformation without damage. Often, it is desirable that the active electronic materials also act as mechanical elements, without need for supporting structures and resistant to damage processes such as buckling and fracture. Engineering reliable, flexible and stretchable devices requires characterizing and then engineering thermomechanical properties, including strength, stiffness, ductility and fracture energy of the constituent materials that are often inherently much lower than conventional electronic device materials.<br/>We review progress and challenges along with strategies for improvement of the thermomechanically properties of flexible and stretchable device technologies. Examples are provided that include organic and small molecule charge-transport layers and semiconducting materials used in flexible devices, displays, and solar cells. This includes the development of a stiff, light-activated, cross-linking node capable of generically transforming any solution processed organic material into a solvent- and fracture-resistant material. We reveal significant opportunities for increasing scalability and manufacturing throughput of reliable devices using spray and atmospheric plasma deposition techniques. In the case of mechanically fragile optoelectronic materials like perovskites, we describe strategies involving polymeric scaffolds that shield the weak perovskite material from external stress, effectively partitioning the perovskite cell into hundreds of mechanically and chemically encapsulated cells. The mechanical integrity of the cell design is completed by covalently bonding cross-linked hole-transporting layers to form a composite scaffold structure that exhibits over a ten-fold increase in fracture resistance. For flexible and stretchable organic devices to be a technological success, improved mechanical properties and reliability cannot be an afterthought to device operating performance, but must be addressed in the development of robust and efficient devices.

Opportunities and challenges for reliable flexible and stretchable polymer devices

256th National Meeting (2018)

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