Recently, advances in the CdTe technology made CdTe a great candidate for commercial thin film solar cells because it is used in infrared windows for optoelectronic devices such as photovoltaic ones. Nowadays, solar cells with nanometric thicknesses are increasingly required due to an enhanced behavior effect. It is common to observe interdiffusion phenomena during several technological processes that are required for the fabrication of photovoltaic devices. It is very important to note that this interdiffusion could strongly affect the final efficiency of devices. In this work, the study of two materials as an interlayer between the CdTe thin film and metallic contact is presented. Te and ZnTe were deposited on the CdTe surface by using a close space sublimation technique. The electrical properties of the devices were evaluated after two and four years to observe the electrical behavior of Te and ZnTe layers implemented as part of the back-contact.