Improvements in printable mesoscopic perovskite solar cells via thinner spacer layers

Abstract

Printable mesoscopic perovskite solar cells based on TiO₂/ZrO₂/carbon mesoporous scaffolds have a promising future in commercialization due to their stability and ease of large-scale manufacturing, in which the mesoporous ZrO₂ (mp-ZrO₂) spacer is crucial in decreasing charge carrier recombination. To obtain high-performance devices, 2–3 μm thick mp-ZrO₂ is usually needed. However, such thickness leads to an increased loading amount of perovskite material and causes problems such as reproducibility, pollution, and waste. Herein, we provide a universal solution to enhance V_OC in printable mesoscopic PSCs with thin mp-ZrO₂ layers. By depositing a thin layer of Al₂O₃ using a spraying pyrolysis method, we successfully retard the recombination between the TiO₂ and carbon electrode. We further find the modification could down-shift the conduction band minimum (CBM) and increase the carrier transportation. Finally, we successfully reduce the mp-ZrO₂ thickness of devices from 3 μm to 1.2 μm while retaining comparable device performance. Thanks to thinner ZrO₂ layers, the usage of solvent and PbI₂ is also reduced, which makes the device both more cost-efficient and environmentally friendly. This modification strategy will pave the way to the commercialization of printable mesoscopic PSCs with greener and cheaper processes.