Study On Preparation And Properties Of TCO Thin Films For HIT Solar Cell

Since the inception of TCO,it has been a hot spot in scientific research.At present,TCO has been widely used in display,solar cells,optical sensors and other optical equipment.Especially in the field of solar cells,TCO rapidly develops with the inception of thin-film solar cells.In HIT solar cell,TCO can be contact to protect the following PN junction,can also be anti-reflective layer by control its thickness,which has an great significance on the performance of the cells.However,different types of TCO has a relatively large difference in their conductivity,light transmission and other properties.Therefore,it is very important to select a suitable TCO for HIT solar cell.At present,the application prospects of ITO and AZO is better in TCO materials.In this paper,ITO and AZO films were deposited on the quartz substrate by RF magnetron sputtering.It is investigated by designing orthogonal experiment that the effects of substrate heating temperature,sputtering power and sputtering pressure on the photoelectric properties of ITO and AZO thin films.The minimum resistivity of ITO film is 2.9×10^-3??cm,and the highest mean transmittance in the range of 400¹100nm is 86.18%.Through the orthogonal experimental data analysis,the optimal conditions are;substrate temperature 80?,sputtering power60W,sputtering pressure 0.1Pa.The surface work function of the film is in the range of4.53⁴.75eV.And the work function can be further regulated by changing the annealing temperature,making it matched with the emitter work function of HIT solar cell.The minimum resistivity of AZO film is 1.7×10^-2??cm,and the highest mean transmittance in the range of 400¹100nm is 93.18%.Through orthogonal analysis,the optimal conditions are;substrate temperature 200?,sputtering power 140W,sputtering pressure 0.1Pa.Under the condition of lower temperature and lower sputtering power,the resistivity of ITO thin films is relatively small,but the resistivity of AZO thin films is relatively large.And the transmittance of the two films is relatively close.Therefore,ITO film is more suitable for HIT solar cells as front contact.