热蒸发镀膜及多晶硅太阳能电池铝背场的研究

发布时间：2018-05-17 12:27

本文选题：多晶硅太阳电池 + 铝背场　；参考：《北京交通大学》2014年硕士论文

【摘要】：晶体硅太阳能电池在目前太阳能电池中占据最大的市场份额。铝背场钝化在硅基太阳能电池效率提高方面起到了巨大的作用。其制备方法主要有丝网印刷、热蒸发、磁控溅射等方法。因为成熟的工艺技术以及低廉的价格,丝网印刷工艺已经在工业化生产中得到了大规模的应用。但是由于大颗粒的铝浆并不能与硅片形成完美的欧美接触,因此利用热蒸发等PVD方法制备所得铝薄膜具有更优异的特性,能进一步提高晶体硅太阳电池的短路电流和转换效率。采用热蒸发真空镀膜技术结合丝网印刷工艺的方式制备得铝背场,具有良好欧姆接触和更高的短路电流。其制备方法简单、兼顾两种工艺的优点成本、钝化性能良好。基于以上介绍,本文主要做了以下工作：自主搭建了可用于大面积(156×156mm2)多晶硅片铝背场制备的热蒸发真空镀膜设备。加热电流范围0—50A,极限真空度达到了5.0×10-4pa,一次铝膜沉积厚度达到2μ m以上,沉积铝膜不均匀度14.10%,基本上满足了多晶硅太阳电池铝背场的制备。对蒸发铝薄膜工艺进行了研究,研究表明铝膜沉积模式为岛式模式,且随着阻蒸电流增大,蒸发颗粒变大,膜层表面变粗糙,在绒面硅片表面呈鱼鳞状沉积。利用热蒸发镀膜机,于电池背面沉积0.21～2.11μm铝膜,研究了铝膜厚度对电池性能的影响。研究表明铝膜厚度对电池性能有较大影响,铝量的多少直接关系到电池电学性能。随着铝膜增厚,转换效率升高,在膜厚为2.11μm时达到最高15.90%。从0.21μ m到2.11μ m,开路电压由0.602V增加到0.611V、短路电流由33.33mA/cm2增加到33.67]mA/cm2、填充因子由70.28%增加到77.64%,串联电由阻5.729mΩ减小到0.025mΩ,并联电阻由最小2.94Ω增加到17.08Ω。铝膜的厚度对电池的各电学参数影响至关重要。利用热蒸发镀膜机结合丝网印刷工艺制备了多晶硅太阳电池,对铝背场金属化进行了研究,研究发现,用热蒸发镀膜制备的铝背场具有更好的欧姆接触更低的串联电阻和更高的短路电流,相比只进行丝印的电池其短路电流最高提高了0.21mA/cm2。通过比较热蒸发与丝网印刷不同工艺制备的电池,以及对电池进行电学和SEM测试,表明薄的蒸镀的铝膜可以形成很好的欧姆接触,更低的串联电阻,但是其较薄的铝层并不能形成很好的钝化层。丝网印刷可以快速制得较厚的铝膜层,但是制备的硅铝合金层疏松空隙较多,不能形成很好的欧姆接触。而蒸镀加丝网印刷的工艺可以兼顾蒸镀和丝网印刷的优势,得到很好的硅铝合金层和p+层,合金层致密无孔,得到更高的开路电压和短路电流。
[Abstract]:Crystal silicon solar cells in the current solar cells account for the largest market share. Aluminum backfield passivation plays an important role in improving the efficiency of silicon based solar cells. The main preparation methods include screen printing, thermal evaporation, magnetron sputtering and so on. Due to mature technology and low price, screen printing technology has been applied in industrial production on a large scale. However, because the aluminum slurry with large particles can not form perfect contact with silicon wafer in Europe and America, the aluminum thin films prepared by PVD method such as thermal evaporation have better properties, and can further improve the short-circuit current and conversion efficiency of crystalline silicon solar cells. The back field of aluminum was prepared by thermal evaporation vacuum coating technology combined with screen printing technology. It has good ohmic contact and higher short circuit current. Its preparation method is simple, the advantages and cost of both processes are taken into account, and the passivation performance is good. Based on the above introduction, the main work of this paper is as follows: A vacuum coating equipment with thermal evaporation was built, which can be used in large area (156 脳 156mm ~ 2) polysilicon wafer. The heating current range is 0-50 A, the limit vacuum is 5.0 脳 10 ~ (-4) paa, the thickness of primary aluminum film is more than 2 渭 m, the uniformity of deposited aluminum film is 14.10 ~ (th), which basically satisfies the preparation of aluminum back field of polycrystalline silicon solar cell. The process of evaporating aluminum film is studied. The results show that the deposition mode of aluminum film is island mode, and with the increase of evaporation current, the evaporation particle becomes larger, the surface of the film becomes rough, and the surface of the film is deposited as a fish scale on the surface of the flannel silicon wafer. The effect of the thickness of aluminum film on the performance of the battery was studied by means of the thermal evaporative coating machine and 0.21 渭 m 2.11 渭 m aluminum film deposited on the back of the battery. The results show that the thickness of aluminum film has a great influence on the performance of the battery, and the amount of aluminum directly affects the electrical properties of the battery. With the increase of aluminum film thickness, the conversion efficiency increases, and the highest value is 15.90 when the film thickness is 2.11 渭 m. From 0.21 渭 m to 2.11 渭 m, the open-circuit voltage increased from 0.602V to 0.611V, the short-circuit current increased from 33.33mA/cm2 to 33.67 Ma / cm ~ (2), the filling factor increased from 70.28% to 77.64m, the series resistance decreased from 5.729m 惟 to 0.025m 惟, and the shunt resistance increased from 2.94 惟 to 17.08 惟. The thickness of aluminum film plays an important role in the electrical parameters of the battery. Polysilicon solar cells were prepared by thermal evaporation coating machine and screen printing process. The metallization of aluminum back field was studied. The lower ohmic contact resistance and the higher short-circuit current are obtained in the aluminum back field prepared by thermal evaporation coating. Compared with the battery with only screen printing, the short-circuit current is increased by 0.21 Ma / cm ~ (2) up to 0.21 Ma / cm ~ (2). By comparing the batteries prepared by different processes of thermal evaporation and screen printing, as well as the electrical and SEM tests of the batteries, it is shown that thin evaporated aluminum films can form good ohmic contact and lower series resistance. But the thin aluminum layer does not form a good passivation layer. Silk-screen printing can make thick aluminum film quickly, but the silicon aluminum alloy layer can't form good ohmic contact due to the large porosity. However, the process of evaporation plus screen printing can give consideration to the advantages of evaporation and screen printing, and obtain good Si-Al alloy layer and p layer. The alloy layer is compact and porous, and higher open circuit voltage and short circuit current can be obtained.
【学位授予单位】：北京交通大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM914.41

【共引文献】