Calcium deposition on poly(para-phenylene vinylene):: Molecular dynamics simulations

There is presently a debate as to the possible interface structures and interaction mechanisms between metal and organic active layers for polymer light-emitting devices. We use a powerful hybrid theoretical methodology-classical molecular dynamics and ab initio density functional calculations-to investigate such interfaces, by simulating the deposition of calcium on pure poly(para-phenylene vinylene) surfaces. We find that the diffusion of Ca atoms into ordered surfaces is not favored; disordered structures may host Ca diffusers, but our results nevertheless indicate that the interaction between the metal atom and polymer chain is very weak, and do not support a mechanism of direct doping with strong charge transfer, or of chemical reactions.