A computational study of surface diffusion of C60 on pentacene

被引:39
作者
Cantrell, R. [1 ]
Clancy, P. [1 ]
机构
[1] Cornell Univ, Sch Chem & Biomol Engn, Ithaca, NY 14853 USA
关键词
Anisotropy; Fullerene (C-60); MM3; potential; Molecular dynamics; Organic heterojunction; Pentacene; Surface diffusion and dynamics; Surface interaction energies;
D O I
10.1016/j.susc.2008.09.027
中图分类号
O64 [物理化学(理论化学)、化学物理学];
学科分类号
070304 ; 081704 ;
摘要
The morphology of the C-60/pentacene heterojunction is of interest for organic photovoltaic applications, yet is not well characterized. With that in mind, all-atom molecular dynamics simulation techniques were used to elucidate the diffusional behavior of small numbers of C-60 molecules on the surface of crystalline pentacene as a probe of the molecular-level interactions between C-60 and pentacene. The ultimate molecular probe of the pentacene surface, a single C-60 admolecule, exhibited an anisotropic diffusion pattern that lingered in energetically preferred sites in the (110) direction, intercepting the (0. 1/2, 0) point in the unit cell. An Arrhenian analysis of this diffusion data gave estimates for the prefactor, D-0, and energy barrier, E-a, of 2 x 10(-3) cm(2)/s and 0.1 eV, respectively. Surface diffusion of one C-60 molecule on pentacene is significantly more rapid (by about 1-2 orders of magnitude) than if even one additional C-60 admolecule is present, implying that the C-60-C-60 cohesion interaction is stronger than the C-60-pentacene adhesion interaction. Simulations with up to four C-60 molecules, the practical limit of an all-atom approach, reinforced the suggestion that C-60 likes to dewet a pentacene surface and will show a preference for forming small 3D nuclei. (C) 2008 Elsevier B.V. All rights reserved
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页码:3499 / 3505
页数:7
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