Enhancing the stability and efficiency of carbon-based perovskite solar cell performance with ZrO-decorated rGO nanosheets in a mesoporous TiO electron-transport layer.

Improving the role of electron-transport layers (ETLs) in carbon-based perovskite solar cells (CPSCs) is a promising method to increase their photovoltaic efficiency. Herein, we employed rGO sheets decorated with ZrO nanoparticles to increase the electron transport capability of mesoporous TiO ETLs. We found that the rGO/ZrO dopant enhanced the conductivity of the ETL, reducing the charge-transfer resistance at the ETL/perovskite interface and reducing charge recombination in the corresponding CPSCs. Notably, this dopant did not effectively change the transparency of ETLs, while increasing the light-harvesting ability of their own top perovskite layer by improving the crystallinity of the perovskite layer. The rGO/ZrO-containing ETLs produced a champion efficiency of 15.21%, while devices with a net ETL recorded a maximum efficiency of 11.88%. In addition, the modified devices showed a higher stability behavior against ambient air than the net devices, which was linked to the passivated grain boundaries of the modified perovskite layers along with the improved hydrophobicity.