© 2023, The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.The In2O3, Yb2O3, and (In, Yb)2O3 thin films were produced by the ultrasonic spray pyrolysis method. The structural and electro–optical properties of (In, Yb)2O3 thin films were compared with those of In2O3 and Yb2O3 thin films. The crystal structure of (In, Yb)2O3 has been reported to be cubic bixbyite, with a lattice constant of 1.030 nm. It was evaluated that the (In, Yb)2O3 material was a direct ultra-wide bandgap semiconductor with a value of 4.11 eV.