The effect of rapid atmospheric plasma treatment of FTO substrates on the quality of TiO2 blocking layers for printed perovskite solar cells

The aim of this work is to investigate and compare rapid ambient air atmospheric plasma treatment with time-consuming standard cleaning procedure for FTO substrates. Cleanliness has immediate and important effects on TiO2 blocking layers and subsequently on the photovoltaic performance of printed carbon-based perovskite solar cells (C–PSCs). The effects of the alternative approaches to FTO cleaning are characterized by XPS, Raman imaging spectroscopy, SEM, and optical microscopy. The C–PSCs treated with low-temperature atmospheric plasma for 10 s exhibited a similar conversion efficiency to that of cells prepared with FTO substrates cleaned by standard procedures (6% vs 6.1%). The results indicate that rapid plasma treatment of FTO substrates can be as effective as standard cleaning, which may employ various toxic organic solvents and time-consuming ultrasonic baths. The highest efficiency (6.3%) was achieved with C–PSCs for which the substrates had been cleaned by combined standard cleaning and 10-s plasma treatment. XPS and Raman measurements confirmed that both standard and plasma treatment significantly reduced organic residues and other contamination on FTO surfaces, enhancing the overall quality of TiO2 blocking layers and the performance of the whole solar device.