en Research Paper Research Paper <div style="text-align: justify;">Tin oxide (SnO2) is used as an electron transport layer (ETL) in perovskite solar cells with a planar<br> structure due to its good transparency and energy level alignment with the perovskite layer. The modification<br> interface of the electron transport layer and the perovskite absorber layer plays an important role in the efficient<br> charge extraction process at the interface. In this study, planar perovskite solar cells with configuration<br> (FTO/SnO2/mixed-cation perovskite/CuInS2/Au) were prepared to investigate the effect of UV-Ozone (UVO) treated<br> SnO2 as ETL on the performance of devices. ETL treatment was performed at different times (0 to 60 min). It is<br> shown that surface wetting was improved by UVO treating the SnO2 films prior to deposition of the perovskite layer.<br> The latter improves the contact between the ETL and the perovskite layer, allowing more efficient electron transport<br> at the interface. Contact angle, SEM, photoluminescence spectra, and the current density-voltage tests were<br> conducted to characterize the photovoltaic of the cells. The best PSC performance with a power conversion<br> efficiency of 10.96% was achieved using UVO-treated SnO2 ETL for 30 min, whereas the power conversion<br> efficiency of the perovskite solar cells with SnO2 ETL without UVO treatment was only 4.34%.</div> SnO2,UV-Ozone,treatment,planar perovskite solar cell 1 9 http://ijmse.iust.ac.ir/browse.php?a_code=A-10-1845-2&slc_lang=en&sid=1 Mohammad Reza Zamani Meymian r_zamani@iust.ac.ir 1800319475328460014788 1800319475328460014788 Yes Department of Physics, Iran University of Science and Technology Razieh Keshtmand r_keshtmand@physics.iust.ac.ir 1800319475328460014789 1800319475328460014789 No Department of Physics, Iran University of Science and Technology