Impacts of the Hole Transport Layer Deposition Process on Buried Interfaces in Perovskite Solar Cells

Perovskite solar cells (PSCs) are one of the emerging solar cell technologies with high conversion efficiency. Several deposition methods had been applied for preparing their hole transport layer (HTL). However, there are few direct evidences to demonstrate whether HTL and its interfaces in PSCs have been influenced by the deposition methods. In this study, the 3D morphology of PSCs has been reconstructed by focused ion beam-scanning electron microscopy from the PSCs in which HTLs are deposited by different methods. The compositional distribution of HTLs is unveiled as well. All these associated layers and interfaces display obvious morphological and compositional differences that are attributed to the HTL components' solubility differences in the precursor solvent. Our investigation demonstrates the PSCs that HTL fabricated by dynamic spin-coating method have higher efficiency, better film uniformity, and less interfacial roughness than the static spin-coating-based devices.