Principal Investigator Robert Macfarlane
programmability of DNA makes it an attractive structure-directing ligand for the assembly of nanoparticle superlattices that mimic atomic crystallization. However, synthesizing multilayer single-crystals of defined size remains a challenge. This work studies growth temperature and interfacial energetics to achieve epitaxial growth of single crystalline nanoparticle thin films over arbitrarily shaped 500 × 500 μm2 areas on lithographically patterned templates. Both surface morphology and internal structure are examined to provide an understanding of particle attachment and reorganization.
Importantly, these superlattices utilize a “soft,” of utilizing rigid building blocks coated with soft elasticallymalleablebuildingblock,resultinginsignificant strain tolerance when subjected to lattice mismatch.
Calculations of interaction potentials, small-angle X-ray scattering data, and electron microscopy images show that the oligomer corona surrounding a particle core can deform to store seven times more elastic strain than atomic films. DNA-nanoparticles dissipate strain both elastically through coherent relaxation of mismatched lattice parameter and plastically (irreversibly) through formation of dislocations or vacancies. Additionally, the DNA cannot be extended as readily as compressed, and thus, the thin films exhibit distinctly different relaxation behavior in the positive and negative mismatch regimes. These observations provide a more general understanding