Cerium oxide standing out as an electron transport layer for efficient and stable perovskite solar cells processed at low temperature

In high performance perovskite solar cells (PSCs), the electron transport layer (ETL) has overwhelmingly been dominated by compact titanium oxide (TiO2), which typically requires sintering at around 500 degrees C. Such a high-temperature sintering procedure prevents TiO2-based PSCs from matching well with plastic substrates and low-cost manufacturing. Here we report cerium oxide (CeOx, x = 1.87), that was prepared facilely through a simple sol-gel method at low temperature (similar to 150 degrees C), as an alternative to high-temperature sintering processed TiO2 in the regular architecture of PSCs. With a PCE of 14.32% from the involvement of an optimized CeOx ETL through adjusting the precursor solution, and a higher PCE of 17.04% through introducing a [6,6]-phenyl-C-61-butyric acid methyl ester (PC61BM) interfacial layer between the CeOx ETL and the perovskite layer, the present work about CeOx-based PSCs renders low-temperature solution-processed CeOx an excellent ETL for high performance perovskite solar cells with improved stability.