Poly crystalline CdTe thin-film solar cells with complex back contact layers

To improve the properties of back contacts of CdTe solar cells, ZnTe:Cu and polycrystalline Cd1-xZnxTe films were deposited by simultaneous evaporation. Investigative data of the configuration and performance indicate that energy gap of Cd1-xZnxTe films assume quadratic connection with zinc content. With increasing of Cu content, energy gap of polycrystalline ZnTe: Cu will decrease. ZnTe/ZnTe:Cu or Cd1-xZnxTe/ZnTe:Cu back contacted cells can reduce the heterogeneous interface state density and modify the structure of energy band of the solar cells. Furthermore, diffusion of Cu can avoid by this compound films in CdTe solar cells. An efficiency of 13.38% of solar cell with dimension of 0.502 cm2 was fabricated.