Researchers from Delft University of Technology in the Netherlands and Campus de Caparica in Portugal have investigated cerium-doped indium oxide (ICO) as a transparent conductive oxide for silicon heterojunction (SHJ) solar cells. The ICO films were deposited using room-temperature RF sputtering, and the process was optimized by adjusting oxygen flow, pressure, and RF power. The 35 nm thick ICO layer has achieved a mobility of 44.22 cm²/Vs, carrier concentration of 1.65×10²⁰/cm³, and resistivity of 8.56×10⁻⁴ Ω·cm. When used in SHJ cells, it has increased short-circuit current by 0.67 mA/cm² and improved power conversion efficiency by 0.55%, reaching 23.6%. According to the researchers, ICO has provided better transparency and lower parasitic absorption than ITO, with added benefits of low-temperature compatibility and reduced carbon footprint despite lower crystallinity.