Development of indium tin oxide stack layer using oxygen and argon gas mixture for crystalline silicon heterojunction solar cells

Indium tin oxide (ITO) films were used as transparent conductive oxide (TCO) layers in crystalline silicon heterojunction (c-Si-HJ) solar cells. An ITO film was deposited by radio frequency (RF) magnetron sputtering with the oxygen-argon (O-2-Ar) gas mixture. The increasing of the O-2/Ar ratio in ITO film deposition resulted in the improvement of transmittance and short circuit current density (J(sc)) of c-Si-HJ solar cells, while film electrical property, fill factor (FF) and efficiency (eta) of the solar cell were decreased. The enhancement of the J(sc) and FF caused by the ITO stack layer on the efficiency of the c-Si-HJ solar cell was investigated. The c-Si-HJ solar cells using an ITO stack layer have a high photovoltaic (PV) parameter compared to conventional ITO (Ar gas) and ITO (O-2-Ar gas mixture) layer. By using an ITO stack layer for a c-Si-HJ solar cell, the efficiency achieved was as high as 18.4%. (V-oc = 702 mV, J(sc) = 34.8 mA/cm(2), FF = 0.75).