Electron-radiation effect on Freon-gas-treated CdTe solar cells

In this study, CdTe solar cells were fabricated, with 12%-13% efficiencies, using CdCl2 dipping and Freon gas treatments and irradiated with a 6-MeV electron beam of various fluences. The efficiency of the CdCl2-dipped samples decreased by approximately 61% at a dose of 1 x 10(16) e/cm(2), while that of the Freon-gas-treated samples was reduced by only 43%. The measured external quantum efficiencies indicated that the short-circuit current density (J(sc)) values of the treated devices differed significantly under the electron-beam irradiation. The Jsc of the CdCl2-dipped samples decreased from 23.5 to 10.8 mA/cm(2), while that of the Freon-gas-treated samples decreased from 24.7 to 16.4 mA/cm(2). The drift mobility values, derived through time-of- flight measurements, decreased by approximately 1000 times in the CdCl2-dipped device and by similar to 100 times in the Freon-gas-treated device at a dose of 1 x 10(16) e/cm(2). These results reveal that in electron-beam-irradiated devices, the treatment method influences the reduction in J(sc).