▎ 摘　　要

Perovskite solar cells (PSCs) based on ZnO have strikingly succeeded recently and researchers are attempting to develop the next generation of affordable and high-power conversion efficiency (PCE (%)) of PSC based on ZnO. The aim of this study is to investigate the effect of reduced graphene oxide (rGO) sheet on the PCE (%) enhancement of nickel (Ni)-doped ZnO and silver (Ag)-doped ZnO at 5 wt% as electron-transport layers (ETLs) in planar PSCs. According to results, with a comparison between Ni-doped ZnO and Ag-doped ZnO ETLs, it is obtained that Ag doping at 5 wt% is helpful in charge carrier separation and, consequently, a reduction in the recombination rate by creating defect states for ZnO-based PSCs is obtained. According to J?V characteristics, the electrochemical impedance (EIS) and Mott-Schottky (MS), using rGO sheet interlayer significantly impacts the electrical properties in un-doped and-doped ZnO-based PSCs. According to the results, the rGO sheet can passivate un-doped ZnO and doped-ZnO ETLs as well as can assist in quickly charge-carrier extraction from the perovskite layer and decrease the recombination in PSCs. (C) 2021 Elsevier B.V. All rights reserved.