Charge Generation at Polymer/Metal Oxide Interface: from Molecular Scale Dynamics to Mesoscopic Effects



The correlation between molecular scale morphology and charge generation across hybrid photovoltaic interfaces made of metal oxides (ZnO and TiO2) and a prototypical electron donor polymer, P3HT, is investigated. Device characterization and UV-NIR transient absorption spectroscopy are used to demonstrate that the local disorder of the polymer chains on the surface of the metal–oxide film provides better electron injection efficiencies than the crystalline phases, though the latter are essential for energy and charge transport. An unambiguous spectroscopic tool is also demonstrated to probe the occupation of the conduction band of ZnO following the electron injection from the polymer through the ultrafast tracking of the Burstein-Moss effect.