N-type nc-SiOx:H film enables efficient and stable silicon heterojunction solar cells in sodium environment

Hydrogenated nanocrystalline silicon oxide (nc-SiOx:H) is promising to replace hydrogenated amorphous silicon (a-Si:H) as the window layer of silicon heterojunction (SHJ) solar cells due to its lower parasitic absorption at short wavelength. In this work, by varying the growth conditions of nc-SiOx:H, we prepared highly conductive, highly transparent phosphorus-doped nc-SiOx:H film, and successfully applied as the window layer of SHJ cells. The short-circuit current density gains 0.5 mA/cm2, together with an improvement of power conversion efficiency by 0.3%, whose average value reaches 24.09% on 6-inch total-area wafers. More importantly, we find these devices show better stability in sodium environment at 85 °C and 85% relative humidity.