SnO2 selective contact layers by room-temperature RF magnetron sputtering: A case study for perovskite solar cells

Tin dioxide (SnO 2 ) is a wide bandgap, n-type semiconductor that has gained relevance as one of the main electron transport materials for the selective contacts of perovskite solar cells (PSCs). On the other hand, although this photovoltaic technology has largely capitalized on wet-coating fabrication steps, research on physically deposited layers in PSCs is gaining increasing attention, mainly owing to the higher degree of patterning conformability of the deposited materials onto textured/structured surfaces. In this study, RF magnetron sputtering is explored as a room-temperature and highly tunable process for the fabrication of the SnO 2 electron transport layers (ETLs) in PSCs, investigating the effect of deposition parameters and post-annealing treatment on the optoelectronic properties of the material and resulting devices. The application of sputter-deposited SnO 2 as an ETM is demonstrated, achieving PCEs of 9.54 % in flexible PET/ITO substrates, greatly surpassing the current record of 5.88 % reported in the literature for flexible PSCs with sputtered SnO 2 ETL.