| Novel large-area electronics, such as drapable solar cell or flexible displays, electronic textiles, electronic paper, sensor skin for robotics or medical prosthesis, require building electronic devices on flexible and deformable substrates. Substrates such as inorganic or organic polymers and stainless steel foils can be deformed into arbitrary shapes. However, metal interconnect wires or continuous thin films, inorganic semiconductor device materials including amorphous silicon and silicon nitride, are brittle and crack easily when such flexible substrates are subjected to significant amounts of mechanical strain. It is therefore desirable to reduce the strains in such devices on deformable substrates. Furthermore, it is important to understand the relationship between the electrical performance of the devices and the applied mechanical strain, especially for strain values that are below the fracture strains, or the strains associated with device damage or loss of device functionality.;The deformation and failure of flexible electronic structures is studied using model systems that include flexible Poly(Di-Methyl-Siloxane) (PDMS) substrates with surface layers of Au thin films that are relevant to interconnects. The failure mechanisms in a model organic solar cell structure are also elucidated. Following the introduction and literature review, in Chapters 1 and 2 respectively, the deformation and relaxation mechanisms are elucidated in PDMS structures produced via curing at different temperatures in Chapter 3. The monotonic failure mechanisms are then examined in Au/PDMS structures in Chapter 4 and cyclic failure mechanisms in Chapter 5. The failure mechanisms in a model organic solar cell structure are then discussed in Chapter 6 before presenting the salient conclusions for future work in Chapter 7. The implications of the results are discussed for the design of flexible/organic electronic structures. |
