Influence of hydrogen doping of In₂O₃-based transparent conducting oxide films on silicon heterojunction solar cells

We report the influence of hydrogen doping of In₂O₃-based transparent conducting oxide (TCO) films, including indium tin oxide (ITO), hydrogenated ITO (ITO:H), In₂O₃ (IO), and hydrogenated In₂O₃ (IO:H), using radio-frequency magnetron sputtering for SHJ solar cells. The purpose of hydrogen doping is to improve the sheet resistance and work function, while Ar-based ITO films play a critical role in maintaining the electrical and optical properties. The thickness of all TCO films was fixed at 100 nm, which showed the lowest sheet resistance of 34 Ω/sq for the IO:H films. All the films showed an average transmission of more than 87% in the visible-wavelength (400–800 nm) region. The work function was enhanced from 4.96 to 5.45 eV with a hydrogen of 3 sccm. SHJ solar cells using IO:H films achieved an efficiency of 23.6% with an open-circuit voltage (V_OC) of 736 mV, a current density (J_SC) of 38.83 mA/cm² and a fill factor (FF) of 82.62%. We performed an improvement in the conversion efficiency of the device with a simulation using the AFORS-HET (automatic for the simulation of heterostructures) program. The efficiency achieved was 25.41% when V_OC = 729 mV, J_SC = 41.3 mA/cm², FF = 84.42%.