The computed and experimental (solid line) C-V characteristics in dark of HTM-free PSC. N-doped HOIP with (without) an n-doped interfacial layer (IF) at Au/HOIP interface is indicated as dash dot (dash) line. P-doped HOIP with (without) a p-doped IF at TiO₂/HOIP interface is indicated as short dash dot (short dash) line. The V_bi values extracted from the IS1 and IS2 intersections are equal to 0.6 and 0.9 V, respectively.