Fig. 3: Strong interaction between metal chalcogenide ETLs and Sn-based perovskite layers.
From: Metal chalcogenide electron extraction layers for nip-type tin-based perovskite solar cells
The electron density distribution of Sn-based perovskites interacting with (a) O2, (b) SnS2 and (c) Sn(S0.92Se0.08)2 molecules, indicating that the Sn(S0.92Se0.08)2 ETL not only circumvents O2 molecules desorption, but also inhibits the reaction between Sn2+ ions in Sn-based perovskites and O2 molecules present in air. GIWAXS patterns of the Sn-based perovskite films grown on (d) TiO2, (e) SnS2, and (f) Sn(S0.92Se0.08)2 ETLs respectively. These results indicate that the Sn(S0.92Se0.08)2 ETL induces the highest crystalline phase purity at the buried interface due to the strong interaction. g The Sn4+/Sn2+ ratios in the Sn 3d5/2 and Sn 3d3/2 regions of the Sn-based perovskite films deposited on different ETLs, including TiO2, SnS2 and Sn(S0.92Se0.08)2 ETLs. The Sn-based perovskite with the Sn(S0.92Se0.08)2 ETL shows the lowest values, indicative of the strongest interaction between the two. h PL and (i) TRPL spectra of Sn-based perovskite films deposited on TiO2, SnS2, and Sn(S0.92Se0.08)2 ETLs, respectively. Both results suggest the fastest electron transfer in the structure of Sn-based perovskite films deposited on Sn(S0.92Se0.08)2 films.
