Enhancing stability and efficiency in perovskite solar cells: insights into inorganic HTL deposition and interface defect passivation

Abstract

The perovskite solar cell (PSC) as an emerging and promising type of solar cell has been extensively studied, but instability is still a major challenge. Replacing the hygroscopic organic hole transport layer (HTL) in PSCs can result in an improvement in the device stability. However, it is still difficult to deposit inorganic HTLs onto the underlying perovskite layer without eroding or distorting it in the regular n–i–p architecture, thereby inducing defects at the interface and reducing the performance of the device. In this study, the performance of PSCs with an inorganic HTL is modelled using SCAPS-1D. The perovskite-HTL interface defect density was varied from 1.0 × 1012 to 1.0 × 1020 cm−3. We realized that, for PSCs based on some hole transport materials (HTMs), the effect of interface defect density was not significant. We observed that the HTL/perovskite valence band offset (VBO) plays a significant role in the phenomenon observed. In particular, a zero or slightly positive VBO results in an increase in both the defect tolerance and device efficiency. This information provides insights into the fabrication of PSCs with improved interface defect passivation and also enables the fabrication of perovskite solar cells based on physically deposited inorganic charge transport materials.