Hole Transport Materials Based Thin Films: Topographic Structures and Phase Transition Thermodynamics of Triphenylamine Derivatives
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- 作者：Jos茅 C. S. Costa ; Lu铆s M. N. B. F. Santos
- 刊名：The Journal of Physical Chemistry C
- 出版年：2013
- 出版时间：May 30, 2013
- 年：2013
- 卷：117
- 期：21
- 页码：10919-10928
- 全文大小：511K
- 年卷期：v.117,no.21(May 30, 2013)
- ISSN：1932-7455
文摘
The topographic structural analysis of thin films of triphenylamine (TPA) derivatives, obtained by vacuum deposition, is presented. The topology of the films is highly dependent on the number of phenyl rings as well on the presence of methyl groups. The glass transition temperatures can be predicted from the melting temperatures, according to the molecular symmetry, flexibility, and molecular size of the amorphous nonplanar materials suitable for long-time use in OLED based devices. A phase transition thermodynamics study, including vapor pressure and heat capacity determinations of some hole transport materials based triphenylamine derivatives (DDP, p-TTP, TPB, TPD, TDAB, and m-MTDAB) is presented. Analysis of the enthalpic and entropic contributions provides an understanding of the fusion temperature differentiation, which results in higher melting points for TDB and TDAB and lower values for TPD and m-MTDAB, due to the presence of meta-CH3 groups. The thermodynamic parameters of sublimation were used to explain the slightly higher volatility of solid DDP relative to p-TTP and the similarity between the volatilities of solids TPB and TDAB.