The Polymer Society of Korea

Abstract

In conventional n-i-p perovskite solar cells, a thin (∼30 nm) SnO₂ electron-transport layer is commonly used. Adding a fine, uniform, nanoscale surface-modification layer onto this delicate SnO₂ optimizes interfacial energy alignment, suppresses backward carrier recombination, and relieves strain within the perovskite. In this work, lanthanum (La) capping introduced onto SnO₂ by chemical bath deposition generates a conduction-band spike at the interface and reduces strain in the perovskite layer. This approach suppresses the formation of the undesired δ-phase of formamidinium lead triiodide (FAPbI₃) at the buried interface, enhances electron transport, and substantially improves device performance, and it also demonstrates strong operational stability under continuous illumination.