Enhanced perovskite solar cells performance with TiOx and SnOx thin films as electron transport layers

We report on the potential application of crystalline thin metal oxide films (TiO_x, SnO_x) with varying stoichiometries in perovskite solar cell devices. The oxides were deposited via reactive e-beam evaporation, involving the sublimation of pure metals under different pressures of pure oxygen, followed by thermal annealing at 200 °C. Variable angle spectroscopic ellipsometry, X-ray diffraction (XRD), contact angle measurements, scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDS) were used to characterize the films. XRD findings confirmed the crystalline phases of SnOx thin films treated at 200 °C for the most oxygen-rich films (deposited at 2e-4 Torr), while TiOx layers exhibited an amorphous phase. FESEM results confirmed that uniform and dense films were generated across the entire substrate surface. Using the measured refractive indices in a computational model, it was demonstrated that optimizing the device design with these films could result in power conversion efficiencies surpassing 25%.