Kinetic Monte Carlo simulation of selective area growth of mix deposited organic molecules

Abstract

The selective area growth approach (namely the self-assembly of molecules on pre-patterned surfaces) that takes into account the properties of organic molecular materials and traditional lithography techniques, is expected to play a significant role in manufacturing organic micro-nano patterns for photoelectric and full-color display. The manufacture of organic devices with tunable multicolor patterned films depends on the control of nucleation distribution of two or more organic molecules by using a selective area growth approach, particularly through the application of mixed deposition growth that can enhance the nucleation efficiency of multicolor thin films. However, till now the issue of mixed deposition growth of two kinds of organic molecules has been rarely reported, owing to the complexity in experimental operation. In this work, the selective area growth of mixed deposition of two kinds of molecules is studied by molecular kinetic Monte Carlo approach in order to find the experimental conditions for separating two kinds of molecular growth. In the simulation, the interaction energy between the two molecules is adjusted and controlled to study its influence on the separately selective area growth of the two molecules. The results show that when the intermolecular interaction energy is weak, the planar molecules and the non-planar molecules exhibit completely different growth behaviors. The most of non-planar molecules gather at the top of the electrode in an island mode, while planar molecules mainly accumulate in a layer-by-layer mode on the sides of the electrode. On the contrary, when the intermolecular interaction energy is strong, the number of non-planar particles on the tops decreases and a large number of planar particles appear. Moreover, on the sides of the electrode, the doping nucleation of planar molecules and non-planar molecules also exists, resulting in the failure of molecular phase separation growth. It proves that the intermolecular interaction energy can affect separately area-selective growth of various organic molecules. Therefore, when several different kinds of molecules are mixed and deposited, relatively pure crystalline monochromatic films can be obtained at the top and on the sides of the electrode, respectively, by appropriately adjusting the intermolecular interaction energy, which can further facilitate the application of multi-color organic micro-nano pattern in display and other fields.