Molecular orientation transformation of pentacene on amorphous SiO2: A computational study on the initial growth stage of physical vapor deposition

Alternative Face-on Thin Film Structure of Pentacene

“…Thus, the face-on phase is kinetically favored when the surface diffusion of molecules is restricted on a cold substrate. These results experimentally support a former study using molecular dynamics (MD) simulations 12 .…”

“…In the case of a “single molecule” (or a small cluster), on the other hand, the face-on stance is generally favored on the substrate surface, since the face-on oriented molecule more positively interacts with the substrate 9,10,12–14 . In this manner, the end-on orientation is mostly driven by the intermolecular interaction; whereas the face-on orientation is induced by the molecule-substrate interaction.…”

Temperature-dependent orientation study of the initial growth of pentacene on amorphous SiO 2 by molecular dynamics simulations

“…We expect that it can prove that the influence of the substrate temperature is no coincidence through comparatively analyzing the influence of the substrate temperature on these two independent systems. The pentacene molecules depositing on sylanol-saturated a-SiO 2 substrate prefer to form normal orientation when the cluster size is larger than 22 [14], so the initial pentacene configurations of the two systems are constructed in the normal orientation, as shown in Figure 2. The time of each simulation is 5 ns to ensure that the pentacene molecules have sufficient time to achieve the equilibrium shape and the data production time is 200 ps.…”

“…All of the MD simulations were performed using the DISCOVER code [25], and both compounds are described using the COMPASS force field [26]. Details in calculations method were described in our previous work [14].…”

“…In particular, several factors can influence the molecular orientation, such as molecular number [9][10][11], substrate material [2], and substrate temperature [12][13]. We have theoretically investigated the molecular orientation of pentacene on amorphous SiO 2 (a-SiO 2 ) substrate [14]. It is found that the initially grown lateral-oriented pentacene cluster will transfer to the normal-oriented one at a critical molecular number and the existence of the sylanol groups on the a-SiO 2 surface will increase the critical molecular number.…”