High‐performance a‐Si1–xOx:H/c‐Si heterojunction solar cells realized by the a‐Si:H/a‐Si1–xOx:H stack buffer layer

We used amorphous silicon oxide (a‐Si_1–xO_x:H) and microcrystalline silicon oxide (µc‐Si_1–xO_x:H) as buffer layer and p‐type emitter layer, respectively, in n‐type silicon hetero‐junction (SHJ) solar cells. We proposed to insert a thin (2 nm) intrinsic amorphous silicon (a‐Si:H) thin film between the thin (2.5 nm) a‐Si_1–xO_x:H buffer layer and the p‐layer to form a stack buffer layer of a‐Si:H/a‐Si_1–xO_x:H. As a result, a high open‐circuit voltage (V_OC) and a high fill factor (FF) were obtained at the same time. Finally, a high efficiency of 19.0% (J_SC = 33.46 mA/cm², V_OC = 738 mV, FF = 77.0%) was achieved on a 100 μm thick polished wafer using the stack buffer layer.