Fabrication of SnO2 by RF magnetron sputtering for electron transport layer of planar perovskite solar cells

Abstract The requirements of electron transport layer (ETL) for high efficiency Perovskite solar cells (PSCs) are, for example, appropriate band energy alignment, high electron mobility, high optical transmittance, high stability, and easy processing. SnO 2 has attracted more attention as ETL for PSCs because it has diverse advantages, e.g., wide bandgap energy, excellent optical and chemical stability, high transparency, high electron mobility, and easy preparation. The SnO 2 ETL was fabricated by RF magnetron sputtering technique to ensure the chemical composition and uniform layer thickness when compared to the use of chemical solution via spin-coating method. The RF power was varied from 60 - 150 W. The Ar sputtering gas pressure was varied from 1 × 10 − 3 - 6 × 10 − 3 mbar while keeping O 2 partial pressure at 1 × 10 − 4 mbar. The thickness of SnO 2 layer decreases as the Ar gas pressure increases resulting in the increase of sheet resistance. The surface morphology and optical transmission of the SnO 2 ETL were investigated. It was found that the optimum thickness of SnO 2 layer was approximately 35 - 40 nm. The best device shows J sc = 27.4 mA/cm 2 , V oc = 1.03 V, fill factor = 0.63, and efficiency = 17.7%.