Damage-free sputtered ITO top electrode for semi-transparent organic solar cells: Protective and electronic role of the MoO3 transport layer

We report on the integration of a sputtered indium tin oxide transparent top electrode for semi-transparent organic solar cells (ST-OSCs). To mitigate sputtering-induced damage to the underlying organic layers, a MoO3 interlayer is introduced, acting simultaneously as a hole transport layer and as a protective buffer layer during the sputtering process. The best-performing ST-OSC, based on wide-bandgap donor polymer PM6 and acceptor GS-ISO, achieved power conversion efficiencies (PCEs) of 4.6% under bottom illumination and 4% under top illumination. Furthermore, a mild thermal annealing (55 °C) for 5 h leads to a significant performance enhancement for ST-OSC, with PCE reaching up to 5.8%, resulting in improved operational stability compared to conventional opaque OSCs over 200 h testing.