Morphological considerations of organic electronic films for flexible and stretchable devices
- PDF / 1,468,519 Bytes
- 7 Pages / 585 x 783 pts Page_size
- 41 Downloads / 229 Views
uction Organic electronics have long been motivated by the prospect of large-area low-cost electronics that can be solution processed onto plastic substrates to enable flexibility. The attribute of flexibility can be advantageous for scalable processing and in applications such as displays and energy harvesting. In cutting-edge applications such as soft robotics,1 biointegrated electronics,2 and electronics that conform to nonplanar surfaces,3,4 physical demands require the devices to go beyond flexible and move into the realm of stretchable. While design approaches for flexibility or stretchability may differ, the thermomechanical behavior of materials takes center stage alongside the electronic properties. From this collective mechanical and electronic perspective, organic conductors, and polymers in particular, represent a highly attractive material system.5 For organic conductors, the molecular structure and film morphology are known to govern electronic properties.6,7 In many cases, these same features directly impact their mechanical behavior. In this article, we provide an overview of recent efforts to establish how organic electronic film morphology impacts
thermomechanical behavior and the relationships to electronic properties. Strategies that have been used to improve the mechanical resilience of the film while retaining electronic properties are also discussed with a focus on organic solar cells and transistors. Furthermore, in stretchable applications, the film microstructure often changes when stretched. Capturing these changes is needed to establish structure–property relationships that will be encountered during operation. Thus, we also consider morphology and electronic property changes that occur in films under large deformation. Note that throughout this article, a number of mechanical properties will be referred to that are important to establish the expected physical response of the material under an external load, including the elastic modulus (E), cohesive and adhesive fracture energy, yield strain, and crack onset strain (COS). The reader is referred to several excellent articles in References 8–10 that discuss their importance to flexible and stretchable devices.
Neat film considerations Organic conductors can be broadly classified as small molecules or polymers. Small molecules are typically brittle solids held
Brendan T. O’Connor, Department of Mechanical and Aerospace Engineering, North Carolina State University, USA; [email protected] Omar M. Awartani, Department of Physics, North Carolina State University, USA; [email protected] Nrup Balar, Department of Mechanical and Aerospace Engineering, North Carolina State University, USA; [email protected] doi:10.1557/mrs.2017.6
108
MRShttps:/www.cambridge.org/core. BULLETIN • VOLUME 42 • FEBRUARY 2017 • www.mrs.org/bulletin © 2017 at Materials Research Society Downloaded from University of Alabama, on 03 Feb 2017 at 14:03:50, subject to the Cambridge Core terms of use, available https:/www.cambridge.org/core/terms. https://doi.org/10.1557/mrs.2017.6
M
Data Loading...
