Microscopic Description of Elementary Growth Processes and Classification of Structural Defects in Pentacene Thin Films
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- 作者：Stijn Verlaak ; Cedric Rolin ; Paul Heremans
- 刊名：Journal of Physical Chemistry B
- 出版年：2007
- 出版时间：January 11, 2007
- 年：2007
- 卷：111
- 期：1
- 页码：139 - 150
- 全文大小：834K
- 年卷期：v.111,no.1(January 11, 2007)
- ISSN：1520-5207
文摘
Elementary growth processes such as kink initiation, adding a molecule to a kink, and adding a moleculebetween two neighboring kinks and between two grains are theoretically studied in pentacene films by addingone molecule at a time to a predefined aggregate. For each molecule, the potential energy surface is calculatedusing the MM3 molecular mechanics force field, which allowed one to identify useful parameters like theenergy barrier for diffusion and the energy to create kinks, as well as defect configurations. Depending onthe properties of the potential energy surface and the resulting growth-condition-dependent probabilities ofinitiating defect configurations in the film, three types of pentacene defects are identified: a thermally activateddefect, an intrinsic defect, and a kinetic defect. Upon film growth, most defects relax into the ideal crystalconfiguration. Bulk defects that resist relaxation have densities lower than 1016 defects/cm3 at typical growthconditions. Grain boundary defects, on the other hand, are very stable. Moreover, interstitial molecules atgrain boundaries are identified as a source of compressive stress.