Selective reactivity-assisted sacrificial additive coating for surface passivation of wide bandgap perovskite solar cells with cesium tetrafluoroborate

A novel method, named “selective reactivity-assisted sacrificial additive coating”, allowed the BF 4 − from the sacrificial additive to react selectively with the Cs + from the perovskite, forming CsBF 4 to passivate the A-site vacancy on the surface.