Impact of Kinetically Restricted Structure on Thermal Conversion of Zinc Tetraphenylporphyrin Thin Films to the Triclinic and Monoclinic Phases
Impact of Kinetically Restricted Structure on Thermal Conversion of Zinc Tetraphenylporphyrin Thin Films to the Triclinic and Monoclinic Phases
复制标题
动力学限制结构对四苯基卟啉锌薄膜热转变为三斜晶和单斜晶相的影响
DOI：
10.1021/acs.jpcc.8b00972
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发表时间：
2018
期刊：
影响因子：
3.7
通讯作者：
Hasegawa Takeshi
中科院分区：
文献类型：
--
作者：
Shioya Nobutaka;Hada Miyako;Shimoaka Takafumi;Murdey Richard;Eda Kazuo;Hasegawa Takeshi
利用p偏振多角度入射分辨光谱（pMAIRS）和掠入射x射线衍射（GIXD）的强大组合，研究了四苯基卟啉锌（ZnTPP）气相沉积膜中沉积速率的函数结构。通过热退火研究发现，沉积速率对薄膜的初始结构及其转化有影响。pMAIRS光谱结果表明，快速沉积速率生成的ZnTPP非晶态薄膜具有“正面取向”，与缓慢沉积速率生成的非晶态薄膜具有“随机取向”的特点。此外，x射线衍射图显示，在缓慢沉积速率下生长的薄膜中含有少量的三斜晶。不同的初始膜结构对ZnTPP膜的热转化有显著影响。具有三斜晶种子的随机取向无定形聚集体通过亚稳三斜相转变为热力学稳定相（单斜相）。另一方面，受动力学限制的结构之后是简单的热转化：分子直接转化为单斜结构，而不是三斜结构。
The powerful combination of p-polarized multiple-angle incidence resolution spectroscopy (pMAIRS) and grazing incidence X-ray diffraction (GIXD) is applied to the structural characterization of zinc tetraphenylporphyrin (ZnTPP) in vapor-deposited films as a function of the deposition rate. The deposition rate is revealed to have an impact on the initial film structure and its conversion by thermal annealing. The pMAIRS spectra reveal that a fast deposition rate yields a kinetically restricted amorphous film of ZnTPP having a “face-on orientation”, which is readily discriminated from another “randomly oriented” amorphous film generated at a slow deposition rate. In addition, the GIXD patterns reveal that the film grown at a slow deposition rate involves a minor component of triclinic crystallites. The different initial film structure significantly influences the thermal conversion of ZnTPP films. The randomly oriented amorphous aggregates with the triclinic crystallite seeds are converted to the thermodynamically stable phase (monoclinic) via the metastable triclinic phase. The kinetically restricted structure, on the other hand, is followed by a simple thermal conversion: the molecules are directly converted to the monoclinic one rather than the triclinic one.