Table 2. Depletion region width, carrier density and maximum electric field at the junction.

Sample	Depletion width Wp/Wn (nm)	Nd (Perovskite) (cm−3) (calculated from the grain boundaries)	ΔCPD (V)	Electric field max. (V/m)
nc-TiO2/MAPbI3	10/35	7 × 1017	0.155	9 × 106
nc-Al2O3/MAPbI3	Wp ≈ 10	7 × 1016	0.12	*