Optical dynamics at the MoO₃/ZnPc interfaces prepared for visible light communications

In this work, MoO₃/ZnPc optical interfaces as signal receivers employable in visible light communication technology (VLC) are studied and characterized. The heterojunctions which are prepared by the thermal evaporation technique under vacuum pressure of 10⁻⁵ mbar are structurally, optically and electrically investigated. The MoO₃/ZnPc exhibited conduction and valance band offsets of values of 3.36 and 3.57 eV, respectively. Analysis of the energy band diagram of the MoO₃/ZnPc heterojunctions has shown the band structure is of broken gap type. The devices exhibited two strong optical conductivity bands in the visible range of light being dominant near 1.80 and 3.50 eV. The modeling of the optical conductivity in accordance with Drude-Lorentz approach have shown that the interfaces can exhibit large drift mobility and large plasmon frequency. In addition to these features, the high terahertz cutoff frequency values make the MoO₃/ZnPc attractive as light signals receivers in the visible range of light. The applicability of the MoO₃/ZnPc interfaces in visible light communication technology (VLC) as signal receivers were tested via 406 nm laser lights. The resulting biasing dependent photosensitivity of the devices under visible light irradiation is promising for using the MoO₃/ZnPc in the VLC technology. (paper)