关键词: HJT太阳电池, 硼掺杂非晶硅发射极, 暗电导率, 掺杂浓度, 梯度掺杂

Abstract: 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 B₂H₆, 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 400 μs and 3 mV could be achieved for the minority carrier lifetime (@Δn=5×10¹⁵ 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.

Key words: HJT solar cell, boron-doped amorphous silicon emitter, dark conductivity, doping concentration, gradient doping