利用沉积速率和衬底温度调控气相沉积的六方柱状玻璃中类液晶有序结构
Using Deposition Rate and Substrate Temperature to Manipulate Liquid Crystal-like Order in a Vapor-deposited Hexagonal Columnar Glass
AI总结：
该研究利用速率-温度叠加（RTS）原理，通过沉积速率和衬底温度调控气相沉积的菲并苝酯六方柱状玻璃的类液晶有序结构，拓展了RTS在有机电子相关液晶形态的应用。
AI中文摘要：
我们研究了一种菲并苝酯的气相沉积玻璃，该物质已知会形成平衡六方柱状相，研究表明可通过沉积过程中沉积速率和衬底温度的选择来调控类液晶有序结构。我们发现速率-温度叠加（RTS，即降低沉积速率与升高衬底温度等效）可用于在宽范围衬底温度（0.75Tg至1.0Tg）内预测和控制气相沉积玻璃中的分子取向。本研究将RTS拓展至新的结构基元——六方柱状液晶有序结构，该结构正被探索用于有机电子学应用。通过表观平均面对面最近邻距离等多项指标，菲并苝酯的气相沉积（PVD）玻璃有序度与冷却平衡液晶制备的玻璃相当；而通过其他指标衡量，PVD玻璃的有序度低于冷却液晶玻璃。我们解释了最大可达到的有序度差异源于液晶自由表面处存在的分子 Mobility 梯度，及其对不同结构重排机制的影响。该自由表面平衡机制解释了RTS原理的有效性，并为气相沉积最易增强的有序类型提供指导。本研究拓展了RTS的适用范围，使其涵盖具有多种高阶液晶形态的分子体系，这些体系可用于新型有机电子应用。
英文摘要：
We investigate vapor-deposited glasses of a phenanthroperylene-ester, known to form an equilibrium hexagonal columnar phase, and show that liquid crystal-like order can be manipulated by the choice of deposition rate and substrate temperature during deposition. We find that rate-temperature superposition (RTS), the equivalence of lowering deposition rate and raising substrate temperature, can be used to predict and control the molecular orientation in vapor-deposited glasses over a wide range of substrate temperatures (0.75Tg to 1.0Tg). This work extends RTS to a new structural motif, hexagonal columnar liquid crystal order, which is being explored for organic electronics applications. By several metrics, including the apparent average face-to-face nearest-neighbor distance, PVD glasses of the phenanthroperylene-ester are as ordered as the glass prepared by cooling the equilibrium liquid crystal. By other measures, the PVD glasses are less ordered than the cooled liquid crystal. We explain the difference in the maximum attainable order with the existence of a gradient in molecular mobility at the free surface of a liquid crystal, and its impact upon different mechanisms of structural rearrangement. This free surface equilibration mechanism explains the success of the RTS principle and provides guidance regarding the types of order most readily enhanced by vapor deposition. This work extends the applicability of RTS to include molecular systems with a diverse range of higher-order liquid crystalline morphologies that could be useful for new organic electronic applications.
