The Manufacture And Performance Of AZO Thin Films And The Application In The Thin Film CIGS Solar Cell

Great development of the research of solar cell has been achieved at the situation of today's world energy crisis increasing seriously. The performance of the high quality solar cells, especially for thin film solar cells, strongly depend on the performance of the transparent conductive film of window electrode layer. Because some its own advantages, ZnO:Al transparent conductive film has been the most commonly used material of the window layer of solar cell. Therefore, associating with the study to the manufacture technics of ZnO:Al transparent conductive film, manufacture technics of solar cells has great significance for the increase of the transform efficiency of the solar cells and the development of the photovoltaic industry.ZnO target contained 2wt%Al₂O₃ was used to prepare the AZO thin films on glass substrate by the radio frequency magnetron sputtering. The relationship between the electrical and optical properties of the thin films and the preparation process conditions have investigated. Moreover, the preparation process parameters of the AZO thin films has been considered under the situations of the preparation process conditions of the CIGS thin films solar cell. In addition, the performance of the solar cells influenced by AZO thin films has been studied.The electrical properties of AZO thin films was used as reference standards to drawback the preparation process conditions of the films. Finally, the optimum preparation process conditions was achieved at 0.05Pa sputtering pressure, 750W sputtering power and 220℃substrate temperature. In the optimum conditions, the square resistance of the AZO thin films is 6.005Ω/sq, the resistivity is 5.9×10^-4Ω·cm, the mobility is 20.3cm²/V·S, and the transmittance is 87.5% at the wavelength of visible range. When H added in the sputtering atmosphere, AZO thin films prepared by high aluminium content of ZnO target didn't show improvement in electrical and optical properties, especially in the transmittance at the wavelength of near infrared area. One possible reason is that the high aluminum content in target results in the high carrier concentration in the film and the high absorption in near infrared area so that the H doping can't lower the optic absorption.Different preparation process conditions of AZO thin films were used in the preparation of CIGS solar cells to study its influence to the performance of the cells. And the result showed that exorbitant sputtering power or substrate temperature may cause the damage of the solar cell. Finally, a optimum preparation process conditions of AZO thin films used for the window layer of CIGS solar cells was obtained at 0.05Pa sputtering pressure, 750W sputtering power, 160℃substrate temperature, and the thickness of the AZO film was 700nm. After improving the preparation process conditions of the absorption layer of the cells, deposited the window layer AZO films at its optimum preparation conditions, a transformation efficiency of 14.2% of the cells was achieved.