混合沉积有机分子区域选择性生长的动力学蒙特卡罗模拟研究

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

由区域选择性生长方法(即分子在预图案表面的自组装技术)制备的有机微纳米图案有望在光电和全彩显示方面发挥巨大作用.而制备多色图案薄膜的有机器件依赖于两种及多种有机分子的成核分配,特别是混合沉积方法的应用有效提高了多色薄膜成核的效率.本文利用动力学蒙特卡罗方法研究了两种分子间的结合能强弱对混合沉积两种分子以实现相分离式生长的影响.结果表明:当分子间结合能较弱时,两种分子表现出完全不同的相分离生长行为,绝大部分的非平面和平面分子分别沉积在电极顶部和侧面;当分子间结合能较强时,电极顶部及侧面都出现了两类分子的掺杂生长,导致了分子相分离生长的失效.研究证明了分子间的结合能会影响多种有机分子选区生长分离的效果,因此混合沉积两种有机分子时,通过适当调整分子间的结合能,在电极顶部和侧面可分别获得较纯结晶的单色薄膜,从而促进了多色有机微纳米图案在微显示等领域的进一步应用.

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 nonplanar 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 nonplanar 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.