General Conditions of Confinement of the Electromagnetic Wave at the Metal-Dielectric Interface

The confinement of electromagnetic waves in a metal-dielectric interface involves a series of applications of practical interest, including optical absorption at interfaces, solar cells, and sensors. The condition used to obtain confinement appears to be insufficient to guarantee the observation of phenomena. In this work, an analytical study of confinement conditions was done without assumed approximations for permittivity. Thus, it has been possible to separate the real and imaginary parts of the wave vector and find the general conditions for confinement, which shows that in several metal-dielectric interfaces, you cannot have a confined wave. This obtained result shows that the wave in interface can cease to exist even with a small change in dielectric constant. Based on these new conditions, we reviewed a wide range of materials that can be used as adjacent to traditional metals (Ag and Au) and calculated their solar cell’s efficiency and the length of propagation.