Dipole formation at organic/metal interfaces with pre-deposited and post-deposited metal

A novel way to directly measure buried dipoles at metal–organic interfaces in organic electronic devices has been demonstrated. It is critical to match the energy levels at metal–organic interfaces in organic electronic devices such as organic solar cells and light-emitting diodes. To determine the most suitable material for the interfacial layer to achieve this, the work function of the cathode needs to be measured before and after depositing the interfacial layer, but this is difficult in conventional devices. Jian Wang and co-workers at South China University of Technology have solved this problem through forming an ultrathin metal layer by titling a shadow mask at a small angle during the evaporation process. Unlike thick metal layers, this ultrathin layer does not screen dipoles, allowing dipoles to be directly measured at interfaces.