The effect of irradiation on the mechanism of charge transport of CdTe solar cell

Abstract

In this paper, CdTe solar cells of ~10% efficiency with a structure of anti-radiation glass/ITO/ZnO/CdS/CdTe/ ZnTe/ZnTe:Cu/Au were irradiated by 1.7 MeV irradiation with various fluences. Testing methods, such as light and dark IV, quantum efficiency, admittance spectroscopy were used to study the performances of CdTe cells before and after irradiation. Comprehensive electron irradiation damage effect on the characteristics and physical mechanism of charge transport were analyzed. The results show that the main junction CdS/CdTe is easy being destroyed and there are two defects induced by high energy electron irradiation, whose positions in the forbidden band are close to 0.46±0.05 eV and 0.44±0.04 eV above the valence band, and capture cross sections are 1.32×10-15 cm2 and 3.09×10-15 cm2, respectively, and under different irradiation fluences, the quantum efficiency of the solar cells decreases, especially in 550nm-800nm. As a result, the short circuit current decreases after irradiation.