Colloidal quantum dot photovoltaics using ultra-thin, solution-processed bilayer In2O3/ZnO electron transport layers with improved stability

Solution-processed colloidal quantum dot (CQD) photovoltaics (PVs) continue to mature with improvements in device architectures and ligand exchange strategies. Carrier selective contacts extract photogenerated charge carriers from the CQD absorber; however, the role of the electron-transporting layer (ETL) in stability remains unclear. Herein, we find that the typically used >100 nm thick ZnO ETL suffers from parasitic absorption and carrier recombination resulting in unstable n–i–p solar cells with faster UV-degradation. We address this by developing an ultrathin (ca. 20 nm), quantum-confined, solution-processed In2O3/ZnO ETL. This bilayer ETL results in solar cells with significantly improved overall stability without compromising performance, with an 11.1% power conversion efficiency hero device.