Low-Temperature (<40 °C) Atmospheric-Pressure Dielectric-Barrier-Discharge-Jet Treatment on Nickel Oxide for p–i–n Structure Perovskite Solar Cells

[Image: see text] A scan-mode low-temperature (<40 °C) atmospheric-pressure helium (He) dielectric-barrier discharge jet (DBDjet) is applied to treat nickel oxide (NiO) thin films for p–i–n perovskite solar cells (PSCs). Reactive plasma species help reduce the trap density, improve the transmittance and wettability, and deepen the valence band maximum (VBM) level. A NiO surface with the lower trap density surface of NiO allows better interfacial contact with the MAPbI(3) layer and increases the carrier extraction capability. MAPbI(3) can better crystallize on a more hydrophilic NiO surface, thereby suppressing charge recombination from the grain boundary and the interface. Further, the deeper VBM allows better band alignment and reduces the probability of nonradiative recombination. NiO treatment using He DBDjet with a scan rate of 0.3 cm/s can improve PSC efficiency from 13.63 to 14.88%.