Fig. 6

Current density versus voltage (J–V) characteristics for single junction solar cells with (a) Cu2O and (b) Cu–O HTL obtained by varying electron affinity (χ) of the HTLs. Energy band diagrams with valance band offset (VBO) at perovskite/HTL interface by varying electron affinity (χ) of (c) Cu2O and (d) Cu–O layers.