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

We demonstrated the methylammonium lead iodide (CH₃NH₃PbI₃) perovskite-based solar cells (SCs) with nickel (Ni)-oxidized nickel oxide (NiO_x) hole transport layer. The CH₃NH₃PbI₃ 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 CH₃NH₃PbI₃ 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.