Stress-driven recrystallization of pentacene films via diffusion-induced ingress of MOF nanocrystals into the grain boundaries

Abstract

Metal-organic frameworks (MOFs) have been identified as versatile candidates for producing functional materials for various applications. However, the growth of MOF thin film becomes challenging due to non-availability of a proper solvent that restricts the use of the materials in electronic sensor fabrication. The receptor molecules in sensors are often used to functionalize the semiconducting channel. However, integrating such molecules degrade the crystallinity of channel materials, leading to poor sensor performance. In this work, we report the growth of a MOF (CPO-27-Ni) thin film and the recrystallization of semiconducting pentacene thin films due to diffusion of the crystallites into the grain boundaries. MOF films were successfully spin coated at various revolutions per minute (rpm) on pentacene surfaces. The growth of MOF films was studied using statistical analysis of rough surfaces by utilizing scaling theory to capture the evolution of surface morphologies. The x-ray reflectivity study unveiled the diffusion-induced ingress of the MOF through the grain boundaries of pentacene films that imparts compressive stress within the grains leading to subsequent rearrangement of pentacene molecules in the thin-film phase and recrystallizes the bulk crystallographic phase, which in a way will enhance the device performance.