| Great problems of environment pollution and energy crisis are increasing seriously at the situation of today’s world economic grows rapidly. To meet the requirement of society for sustainable development, exploring new green energy has become an important issue facing all countries in the world. Among the new energy sources, such as nuclear, wind and geothermal energy, solar cell has become a top priority for researchers as a sunrise industry in the future. The performances of high quality solar cells, especially thin film solar cells, strongly depends on the performance of the TCO materials which is used to make the transparent electrodes of the solar cells. Therefore, it is of great significance for photovoltaic conversion efficiency, even the development of the photovoltaic industry to explore new film preparation process and continuously improve the material properties of thin films.ZnO target contained 3wt% A12O3 was used to prepare the AZO thin films by radio frequency magnetron sputtering on the glass substrate. Relationships between electrical and optical properties of the films and the preparation process conditions have been investigated in this paper. Moreover,the pin-type μc-Si/c-Si hetero-junction solar cell has been focused on by using the AFORS-HET software, to simulate the performances with different parameters. Some meaningful results were achieved:(1) The electrical properties of AZO films were used as reference standards during the preparation and research of the films. Finally, the optimum conditions were achieved at the working pressure of 0.5Pa, 200 W sputtering power, 300℃ substrate temperature and 40:0.5 oxygen ratio. In this conditions, the square resistance of the film was 290?/cm2, the resistivity was 5.7×10-3?/cm, and within the range of visible light, the transmittance of the film was 82.5%.(2) As the simulation results showed, the emitter layer parameters had great significance for the solar cells. The highest efficiency of the cells was achieved at the thickness of emitter layer was 5 nm, the concentration of doping was 1020 cm-3, the band gap was 1.7eV, and the highest conversion efficiency was of 22.68%.(3) The best intrinsic layer thickness was 3nm, and when the band gap was less than 1.6eV, the performance is not be affected, continue to increase the thickness and the band gap, the performances of solar cells decreased quickly, even lose the photoelectric conversion function.(4) When the defect density interface state(Dit) is less than 1012cm-2·eV-1, the effect on the solar cell performances was limited, and when the density was larger than 1014 cm-2·eV-1, the performances of the cells fell sharply.(5) The thickness of ZnO thin films has an direct effect on the performances of solar cells. As the simulation results, the best thickness was 200 nm.In conclusion, as the ideal of pin-type microcrystalline silicon/silicon hetero-junction cell model, the emitter layer thickness was 5nm, doping concentration was 1x1020cm-3, width of band gap was 1.7eV, the intrinsic layer thickness was 3nm, band gap width was less than 1.6eV, the interface state density was less than 1014 cm-2 eV-1. In this conditions, the VOC=677.3mV, FF =84.08%, JSC=39.82mA/cm2, η=22.68%. As front transparent electrode of the solar cell, when the thickness was 200 nm, the optimum battery conversion efficiency was 21.05%. |
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