An intrinsic amorphous silicon oxide and amorphous silicon stack passivation layer for crystalline silicon heterojunction solar cells

•Intrinsic amorphous silicon oxide and amorphous silicon stack passivation layer.•Photovoltaic parameters were improved by stack passivation layer.•Crystalline silicon heterojunction solar cells with stack passivation layers.

Intrinsic amorphous silicon oxide (i-a-SiO:H) films were used as passivation layers in crystalline silicon heterojunction (c-Si-HJ) solar cells. The effective lifetime (τeff) and photovoltaic (PV) parameters were improved by controlling the CO2/SiH4 ratio in the i-a-SiO:H rear passivation layer. The enhancement of the open circuit voltage (Voc) and solar cell efficiency (η) caused by the i-a-SiO:H/i-a-Si:H stack passivation layer was investigated. The c-Si-HJ solar cells using an i-a-SiO:H/i-a-Si:H stack passivation layer showed a high Voc and η compared to using a conventional i-a-SiO:H passivation layer. The highest efficiency obtained for a c-Si-HJ solar cell using an i-a-SiO:H/i-a-Si:H stack passivation layer was 19.4% (Voc = 715 mV, Jsc = 34.9 mA/cm2, FF = 0.78).