Fig. 5. Cross-sectional TEM image obtained from perovskite solar cell with (a) the thermal-NiOx HTL, (b) the spin-NiOx HTL. And enlarged HR-TEM images obtained from (c) interface between thermal-NiOx and the perovskite active layer, and interface between ITO and thermal-NiOx, (d) interface between spin-NiOx and perovskite active layer.
