氧化硅及多晶硅对TOPCon太阳能电池性能的影响

The influence of silicon oxide and polysilicon on the performance of TOPCon solar cells

TOPCon电池采用超薄氧化硅与掺杂多晶硅对晶体硅前后表面进行钝化并实现选择性载流子输运,提高了晶体硅太阳能电池的效率,但其中的一些物理机理尚未完全被理解.从理论上模拟研究了氧化硅厚度、氧化硅中的介孔密度、多晶硅掺杂浓度等参数对TOPCon太阳能电池性能的影响.结果表明:电池的性能随着氧化硅厚度的增加呈先缓慢提升后急剧下降的趋势,当氧化硅厚度为1.2 nm时,电池的转换效率最大;氧化硅厚度太大会降低载流子的隧穿概率,厚度太薄使得界面钝化效果变差;如果氧化层中有合适的针孔密度,如10^(-4)~10^(-6),复合电流占主导地位,器件仍能获得大于24%的效率;当氧化硅中介孔密度大于10^(-2)时,氧化硅的钝化效果变差且与厚度无关;多晶硅层的重掺杂是获得高效率TOPCon电池的前提,而且重掺杂降低了电池性能对氧化硅厚度的敏感性.

TOPCon solar cells used ultra-thin silicon oxide and doped poly-crystalline silicon to passivate the front and back surfaces of crystalline silicon and realize selective carrier transport,which improved the efficiency of crystalline silicon solar cells,but some of the physical mechanisms had not been fully understood.The effects of thickness of silicon oxide,pinhole density in silicon oxide and doping concentration of poly-crystalline silicon on the performance of TOPCon solar cells were studied theoretically.The simulation results showed that the device performance increased slowly with the increase of the thickness of silicon oxide,and then deteriorated rapidly;When the thickness of silicon oxide was 1.2 nm,the device efficiency reached the highest;If the thickness of silicon oxide was too thin,the carrier tunneling probability reduced;If the thickness of silicon oxide was too thin,the interface passivation effect worsened;If there was a suitable pinhole density in the oxide layer,such as 10^(-4)-10^(-6),the recombination current was dominant,and the device still achieved more than 24%efficiency;When the pinhole density of silicon oxide was greater than 10^(-2),the passivation effect of silicon oxide became worse and seemed independent on the thickness;Heavy doping of polysilicon layer was the premise of obtaining high efficiency TOPCon solar cells,and heavy doping reduced the sensitivity of battery performance to the thickness of silicon oxide.