Using atomic layer deposition, a research team from the City University of Hong Kong has created an an oxygen-deficient tin oxide layer to replace the more common fullerene electron transport layer in perovskite solar cells. The result is a 25%-efficient device that is able to retain around 95% of its efficiency after 2,000 h.
This seems to be a step towards a solution / a solution.
Although there’s a company which has supposedly already solved it completely.
Oxford PV recently had a commercial sale of a perovskite solar panel with a 25 year guarantee