高效背结异质结太阳电池硼掺杂非晶硅发射极研究

Study on Boron-Doped Amorphous Silicon Back-Junction of High Efficiency Heterojunction Solar Cells

晶硅/非晶硅异质结(HJT)太阳电池由于具有高开压、高转换效率和低温度系数等优点而备受关注,其中硼掺杂p型非晶硅(p-a-Si∶H)发射极是高转换效率电池中不可忽视的重要部分,改变其硼掺杂浓度,可以调节p-layer薄膜的电学特性,从而直接影响电池转换效率。本文采用等离子体增强化学气相沉积(PECVD)设备制备HJT太阳电池,通过改变B_(2)H_(6)的掺杂浓度,对电池中p-a-Si∶H层进行优化,使HJT电池获得0.75%的相对效率提升。进一步地,将发射极设置为梯度掺杂的双层结构,经过优化,少子寿命(@Δn=5×10^(15)cm^(-3))和隐开路电压(@1-Sun)分别提升400μs和3 mV,最终具有梯度掺杂发射极的电池其平均效率相对提升2.03%,主要表现为FF和Voc的明显增加,实现了高效HJT电池p型发射极的工艺优化。

The crystalline silicon/amorphous silicon heterojunction(HJT)solar cells have attracted much attention due to their advantages of high open-circuit voltage,high conversion efficiency and low temperature coefficient.As the emitters of cell,boron-doped p-type amorphous silicon(p-a-Si∶H)thin films play an important role in achieving high conversion efficiency.By changing the boron doping concentration,the electrical properties of the p-layer can be adjusted,and therefore the conversion efficiencies of solar cells are directly affected.In this article,plasma enhanced chemical vapor deposition(PECVD)device was used to deposite amorphous silicon thin films applied in the crystalline silicon/amorphous silicon HJT solar cells.By changing the doping concentration of B_(2)H_(6),p-a-Si∶H layer in the cells was optimized.As a result,the relative efficiency of HJT cell was improved by 0.75%.Further,gradient doped double-layer emitter structure was adopted.An improvement of 400μs and 3 mV could be achieved for the minority carrier lifetime(@Δn=5×10^(15) cm^(-3))and implied V oc(@1-Sun)respectively.Eventually benefiting from an obvious boost in FF and V oc,the efficiency of the solar cells was increased by 2.03%relatively and an optimized p-type emitter process was therefore established.