Lowering the operating temperature of solid oxide fuel cells (SOFCs) is essential for realizing their potential in the stationary and portable energy space. Synthesis of SOFCs using thin-film electrolytes enables high-performance devices at reduced temperatures and unique processing capabilities. A nanoscale compositionally graded electrolyte developed by K. Kerman et al. on page 656 using a co-sputtering fabrication method provides selective interfacial functionality and synergistically combines the advantages of multiple materials. An atomistic model of such a structure is shown in the image.