Investigation of Tin Oxide Atomic Layer Deposition on the Performance of Evaporated Perovskite Solar Cells

Although tin oxide (SnO x ) layers grown using atomic layer deposition (ALD) are routinely employed in p‐i‐n perovskite solar cells (PSCs), the correlation between ALD process parameters, SnO x film properties, and PSC performance remains insufficiently investigated. This work examines the role of co‐reactants, H 2 O and H 2 O 2 , and their doses in influencing SnO x material properties and the performance of evaporated p‐i‐n PSCs. H 2 O 2 ‐SnO x exhibits higher film density and higher electron affinity compared to H 2 O‐SnO x ; however, PSCs incorporating H 2 O‐SnO x demonstrate superior performance. The performance of PSCs containing H 2 O 2 ‐SnO x is limited by an undesired chemical interaction between H 2 O 2 and the underlying structure, which can be mitigated by employing a thin layer of H 2 O‐SnO x prior to the deposition of H 2 O 2 ‐SnO x on top of the perovskite/C 60 structure. Furthermore, the H 2 O dose used during the ALD of SnO x substantially affects PSC performance. High H 2 O dose‐SnO x yields the highest power conversion efficiency (19%), whereas low H 2 O dose‐SnO x results in the lowest efficiency (11.3%). Low H 2 O dose‐SnO x exhibits low film density and excess ligand impurities, which can act as charge traps and introduce transport barrier when incorporated into PSCs. Therefore, high H 2 O doses are indispensable during ALD of SnO x to achieve efficient PSC performance.