Organic Nanolayers for Stress Relief at Inorganic Interfaces

Abstract

Defect formation and fracture at inorganic interfaces from stresses generated in the constituent materials during synthesis and thermal treatments are ubiquitous phenomena of wide relevance in thin film heterostructures and nanocomposites. Current mitigation strategies rely on introducing interfacial layers and/or structural changes to enable elastic and plastic deformation processes that preclude interface fracture. Here, we present a completely new strategy to relieve stress and obviate failure by inserting an interfacial organic molecular nanolayer (MNL). Molecular dynamics simulations indicate MNL-induced stress relief by sequential MNL/inorganic interface debonding and reformation, without compromising adhesion. Such MNL-induced bond-switching activation energy is several-fold smaller than the inorganic interface bond energy. Stress relief is a function of MNL coverage, with defective coverage facilitating greater stress relief than full-coverage MNLs. This remarkable result is due to defect-mediated bond-switching and conformation changes, making MNL-induced stress relief tailorable and practical. These findings open up an entirely new framework of nanomolecularly engineering inorganic thin film interfaces during synthesis and annealing for diverse applications including nanoelectronics, energy conversion, and nanocomposite design.