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

Although tin oxide (SnOx) layers grown using atomic layer deposition (ALD) are routinely employed in p-i-n perovskite solar cells (PSCs), the correlation between ALD process parameters, SnOx film properties, and PSC performance remains insufficiently investigated. This work examines the role of co-reactants, H2O and H2O2, and their doses in influencing SnOx material properties and the performance of evaporated p-i-n PSCs. H2O2-SnOx exhibits higher film density and higher electron affinity compared to H2O-SnOx; however, PSCs incorporating H2O-SnOx demonstrate superior performance. The performance of PSCs containing H2O2-SnOx is limited by an undesired chemical interaction between H2O2 and the underlying structure, which can be mitigated by employing a thin layer of H2O-SnOx prior to the deposition of H2O2-SnOx on top of the perovskite/C60 structure. Furthermore, the H2O dose used during the ALD of SnOx substantially affects PSC performance. High H2O dose-SnOx yields the highest power conversion efficiency (19%), whereas low H2O dose-SnOx results in the lowest efficiency (11.3%). Low H2O dose-SnOx exhibits low film density and excess ligand impurities, which can act as charge traps and introduce transport barrier when incorporated into PSCs. Therefore, high H2O doses are indispensable during ALD of SnOx to achieve efficient PSC performance.