Fig. 3: Characterization of perovskite solar cells with PTAA as the HTL behind carbon top electrode.

a, b Steady-state PL spectra and XPS spectra mapping (for I and Pb) of MAPI/ PTAA samples before and after washing by 2-methylanisole and, c–f JV curves and statistical distribution of PCE of PSCs with different concentrations (thicknesses) of PTAA as the HTL with gold (c, d) and carbon (e, f) top electrodes.