Structural characterization of a pentacene monolayer on an amorphous SiO2 substrate with grazing incidence X-ray diffraction
Structural characterization of a pentacene monolayer on an amorphous SiO2 substrate with grazing incidence X-ray diffraction
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DOI：
10.1021/ja049726b
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发表时间：
2004-04-07
影响因子：
15
通讯作者：
Toney, MF
中科院分区：
文献类型：
--
作者：
Fritz, SE;Martin, SM;Toney, MF
掠入射X射线衍射表明，并五苯单层，生长在无定形SiO2基板，通常用作有机薄膜晶体管（OTFT）的介电层，是结晶的。一个初步的能量最小化模型的单层，GIXD数据的基础上，揭示了并五苯分子采用人字形排列，其长轴从基板正常略有倾斜。虽然这种排列类似于块状并五苯单晶中（001）层的一般堆积特征，但单层晶格参数和晶体结构不同于块状并五苯的那些。由于并五苯OTFT中的载流子输运被认为发生在电介质界面附近的半导体层中，因此在非晶SiO2上发现结晶单层结构对OTFT中的输运具有重要意义。
Grazing incidence X-ray diffraction reveals that a pentacene monolayer, grown on an amorphous SiO2substrate that is commonly used as a dielectric layer in organic thin film transistors (OTFTs), is crystalline. A preliminary energy-minimized model of the monolayer, based on the GIXD data, reveals that the pentacene molecules adopt a herringbone arrangement with their long axes tilted slightly from the substrate normal. Although this arrangement resembles the general packing features of the (001) layer in single crystals of bulk pentacene, the monolayer lattice parameters and crystal structure differ from those of the bulk. Because carrier transport in pentacene OTFTs is presumed to occur in the semiconductor layers near the dielectric interface, the discovery of a crystalline monolayer structure on amorphous SiO2has important implications for transport in OTFTs.