Fig. 5

Electroabsorption probe of internal electric field. a Electroabsorption (EA) spectrum acquired in differential reflectivity from a device depleted in reverse bias at −2 V with a 0.8 V peak-to-peak sinusoidal dither at a modulation frequency of 389 Hz. b Transient EA signal resulting from a −2 to 2 V square wave signal with a 10 ms period. c Increasing the square wave period to 2 s leads to a decay of the EA signal during each half cycle that indicates screening of the internal electric field in the perovskite layer