Impact of electron-phonon interaction on metal-organic interface states

Abstract

The interface state (IS) between a noble metal and an organic layer shifts to lower energy by $\ensuremath{\sim}100$ meV when heated from zero to room temperature. Here, we show that this shift can only be explained including the energy renormalization caused by a quantum-mechanical electron-phonon interaction (EPI) between molecular vibrations and the IS. We investigate the EPI by a simplified model on the bases of ab initio data. By combining EPI with a classical thermal lifting effect of the molecular layer, we explain the recently published temperature-dependent experimental data for the NTCDA/Ag(111) system.