Surface and Interface Engineering of Tin Oxide Electron Transport Layers: Recent Progress and Perspectives for Perovskite Photovoltaics

초록

Tin oxide (SnO2) has emerged as the most widely used electron transport layer (ETL) in perovskite photovoltaics because of its wide bandgap, high transparency, high chemical stability, low-temperature processability, and favorable energy alignment with perovskite absorbers. However, pristine SnO2 suffers from intrinsic defects such as insufficient electron mobility and high density of trap states, which limit the performance and stability of the device. Over the past decade, significant efforts have been made to modify SnO2 to overcome these challenges. In this review, we summarize recent advances in SnO2 modification strategies, including surface passivation, self-assembled monolayers, double-ETL architectures, and interface engineering with functional interlayers. We highlight how these approaches mitigate the defect states, tune the energy levels, and improve the carrier extraction. By systematically comparing the fabrication routes and modification techniques, this review provides an integrated perspective on the role of SnO2 in high-performance perovskite solar cells.

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