Interface formation and energy level alignment of pentacene on SiO2

We examined the interface formed by pentacene deposition onto a SiO2 substrate. We found that upon pentacene deposition onto SiO2 the pentacene vacuum level aligns with that of SiO2. We observe the immediate appearance of a measurable pentacene highest occupied molecular orbital upon deposition of as little as 2 Å of pentacene onto the SiO2 surface. This suggests that there are no chemical bonds at these interfaces. Measurements that examine the behavior of pentacene deposited onto SiO2 show ordered growth of pentacene with no sign of chemical interaction or charge transfer.