Vacuum deposited film growth,morphology and interfacial electronic structures of 2,7-dioctyl[1]benzothieno[3,2-b]benzothiophene(C8-BTBT)  

2,7-二辛基[1]苯并噻吩并[3,2-b]苯并噻吩(C8-BTBT)的真空沉积薄膜生长、形貌和界面电子结构

作　　者：WEI Jun-hua NIU Dong-mei GAO Yong-li 魏俊华;牛冬梅;高永立(Hunan Key Laboratory of Super Microstructure and Ultrafast Process,School of Physics and Electronics,Central South University,Changsha 410083,China;Department of Physics and Astronomy,University of Rochester,Rochester,NY 14627,USA)

机构地区：[1]Hunan Key Laboratory of Super Microstructure and Ultrafast Process,School of Physics and Electronics,Central South University,Changsha 410083,China [2]Department of Physics and Astronomy,University of Rochester,Rochester,NY 14627,USA

出　　处：《Journal of Central South University》2022年第4期1041-1061,共21页中南大学学报（英文版）

基　　金：Project(2017YFA0206602)supported in part by the National Key Research and Development Program of China。

摘　　要：Interfaces play critical roles in electronic devices and provide great diversity of film morphology and device performance.We retrospect the substrate mediated vacuum film growth of benchmark high mobility material 2,7-dioctyl[1]benzothieno[3,2-b]benzothiophene(C8-BTBT)and the interface electronic structures.The film growth of C8-BTBT molecules is diversified depending on the substrate-molecule and molecule-molecule interactions.On atomic smooth substrates C8-BTBT film grows in layer-by-layer mode while on coarse substrate it grows in islands mode.The initial molecular layer at dielectric,semiconductor and conductive substrates displays slight different lattice structure.The initial molecule orientation depends on the substrate and will gradually change to standing up configuration as in bulk phase.C8-BTBT behaves as electron donor when contacting with dielectric and stable conductive materials.This usually induces a dipole layer pointing to C8-BTBT and an upward bend bending in C8-BTBT side toward the interface.Although it is air stable,C8-BTBT is chemically reactive with some transition metals and compounds.The orientation change from lying down to standing up in the film usually leads to decrease of ionization potential.The article provides insights to the interface physical and chemical processes and suggestions for optimal design and fabrication of C8-BTBT based devices.两种材料的界面是物质交换和能量交换的场点,在电子器件中起着关键作用。同种材料可在不同基底材料上形成多种不同的薄膜形态,并展现不同的器件性能。本文综述了高迁移率有机小分子半导体2,7-二辛基[1]苯并噻吩并[3,2-b]苯并噻吩(C8-BTBT)在不同的功能材料上的真空沉积薄膜生长、界面过程以及界面电子结构。C8-BTBT分子的薄膜生长取决于衬底与C8-BTBT以及C8-BTBT分子之间的相互作用。在原子级光滑衬底上,C8-BTBT薄膜一般以层状模式生长,而在粗糙衬底上,C8-BTBT薄膜倾向于岛状模式生长。在电介质、半导体和导电衬底上沉积的初始C8-BTBT分子层显示出略有不同的晶格结构。界面层C8-BTBT分子的取向取决于衬底与有机分子的相互作用,但是在厚膜情况下表面层终将改变为直立构型。C8-BTBT与电介质或高功函数导电材料接触时表现为电子供体,这通常会诱导出指向C8-BTBT的界面偶极层,以及C8-BTBT侧朝向界面的向上能带弯曲。尽管C8-BTBT具有空气稳定性,但仍会在某些过渡金属,如镍、钴和化合物界面发生化学反应。C8-BTBT界面电子结构与其薄膜形貌和分子取向有关,当膜厚增加、分子取向从平躺到直立时,C-H会形成表面偶极层,导致电离能减小。本文提供了C8-BTBT的界面物理和化学过程的机制分析,并为基于C8-BTBT的电子器件的优化设计和制造提供参考。

关 键 词：interface film morphology packing configuration growth mode electronic structure chemical reaction interface dipole 

分 类 号：TN03[电子电信—物理电子学] TB383.2[一般工业技术—材料科学与工程]