Optoelectrical Properties and Back Contact Characteristic of VSe2 Thin Films

VSe2 thin films were prepared by using electron beam evaporation method and subsequently annealed at different temperatures. The structural, morphological. optical and electrical properties of VSe2 thin films were characterized by XRD, SEM, optical transmission spectra, Hall coefficients and in situ conductivity measurements. And the back contact characteristic of CdTe solar cells with VSe2 was investigated by dark J-V measurements. The results show that the films are crystallized in a stable hexagonal phase after annealing. The direct optical band gap value Eg for the films, showing p-type conduction mechanism, is found to be about 2.35 eV. The roll-over phenomenon in CdTe solar cells is eliminated and the device performance effectively improves when VSe2 is used as a back contact.