Improved Air Stability of Tin Halide Perovskite Solar Cells by an N-Type Active Moisture Barrier

Tin halide perovskite solar cells are promising for the next generation of highly efficient photovoltaics. Their commercialization can be accelerated by increasing their stability in moisture and oxygen. Herein, an n-type organic molecule (IO-4Cl) is applied as an interlayer between the perovskite films and electron transport layers in p-i-n structured devices. The electron-rich indacenodithieno-[3,2-b]thiophene enhances electron transport, while the hydrocarbon side chains and rigid conjugated backbone isolate air. It is also shown that the CO in IO-4Cl can coordinate with Sn2+ on perovskite films' surface and grain boundaries to enhance perovskite crystal stability. In addition, IO-4Cl slows down crystallization dynamics, resulting in lower non-radiation recombination. The moisture ingress in the perovskite films is tracked under high relative humidity (RH) and it is found that IO-4Cl can mitigate moisture infiltration. Finally, the devices with IO-4Cl maintain 95% of the initial power conversion efficiency after 1200 h of storage in a nitrogen-filled glovebox, and their stability in ambient air (60-80% RH) is significantly improved against pristine devices, thus demonstrating the beneficial effects of IO-4Cl interlayer on device stability. Tin halide perovskites often suffer inferior air stability. Herein, a conductive hydrophobicity n-type IO-4Cl is used to cover crystal grain boundaries and surfaces of tin halide perovskite films, creating a physical barrier against moisture and oxygen infiltration. image

Automated summary

This study demonstrates the use of an n-type organic molecule, IO-4Cl, as an interlayer to improve the stability of tin halide perovskite solar cells. IO-4Cl acts as a physical barrier against moisture and oxygen infiltration and enhances electron transport while slowing down crystallization dynamics. The IO-4Cl interlayer significantly improves device stability, maintaining high power conversion efficiency after long-term storage and in ambient air conditions.