A wide range of processing methodologies and additives have been explored to synthesize the black perovskite phase with the primary goal to make a good quality defect-free black-FAPbI 3 and avoid the formation of the yellow phase. However, perovskite electronics often suffer from the problem of stability and reproducibility. This is mainly due to the lack of control over the crystallization process where several fundamental questions yet remain unanswered, such as (a) why a direct conversion of yellow to black phase by heating