Perovskite-Based Solar Cells With Nickel-Oxidized Nickel Oxide Hole Transfer Layer

We demonstrated the methylammonium lead iodide (CH
₃
NH
₃
PbI
₃
) perovskite-based solar cells (SCs) with nickel (Ni)-oxidized nickel oxide (NiO
_x
) hole transport layer. The CH
₃
NH
₃
PbI
₃
perovskite-based SCs with Ni-oxidized NiOx have better short-circuit current density (J
_SC
), open circuit voltage (V
_OC
), and conversion efficiency (η%) than poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate) (PEDOT:PSS). In addition, the transmittance and work function increased with increasing oxidation temperature of Ni-oxidized NiOx layer. The larger transmittance and work function of Ni-oxidized NiO
_x
could result in less light absorption and hole transport energy loss, respectively. Furthermore, Ni-oxidized NiO
_x
at 450 °C shows the smoothest surface morphology, which could result in the spin-coated CH
₃
NH
₃
PbI
₃
perovskite film to have better crystal quality. Therefore, the SCs with 450 °C Ni-oxidized NiO
_x
hole transport show the largest η% of 7.75% that is ~1.78 times larger than that of SCs with PEDOT:PSS hole transport layer.