Room-temperature processed high-quality SnO₂ films by oxygen plasma activated e-beam evaporation

Recently, SnO₂ is considered to be one of the most promising materials as electron transport layer in perovskite solar cells (PSCs). Low-temperature processed SnO₂ films are crucial for SnO₂-based PSCs and flexible devices. However, it is difficult to prepare stoichiometric SnO₂ films by e-beam evaporation at low-temperature. Herein, SnO₂ films are fabricated by oxygen plasma activated e-beam evaporation technique at room-temperature. Oxygen plasma shows strong oxidation activity, which is essential to adjust the stoichiometry of SnO _x in the evaporation process. The SnO₂ films exhibit uniformity (R _q  = 3.05 nm), high transmittance (T > 90%), high hall mobility (μ _e  = 10.8 cm² V ^-1 s^-1) and good hydrophilic (water contact angle =19°). This work will promote the application of SnO₂ films in PSCs and flexible devices.