Fig. 3. Optoelectronic properties of perovskite films and photovoltaic devices performance.

a, Transient PL decays of reference and DMPESI-passivated (3 mg ml⁻¹) perovskite films on glass with and without HTL. The fits are obtained from the multi-exponential decay function, which were used to calculate the differential lifetimes. The saturated coloured balls correspond to PL decays of perovskite on glass (shown in grey box) with (red) and without (black) DMPESI. The non-saturated coloured circles correspond to PL decays of perovskite on glass with an HTL on top (shown in lilac box). b,c, Differential decay time of passivated perovskite films with HTL plotted as a function of time after excitation (b) and quasi-Fermi level splitting (c). As the concentration of the DMPESI increases, the suppression of the surface recombination increases as well (up to 3 mg ml⁻¹), but the charge extraction efficiency decreases. d, J–V curves of the control (black) and (3 mg ml⁻¹) DMPESI-treated (red) devices, reverse scan (RS) and forward scan (FS) are indicated as solid symbols and open symbols, respectively. Inserted table summarized the corresponding photovoltaic parameters. e, PCE of the device employing DMPESI (3 mg ml⁻¹) treatment device at maximum power point as a function of time at room temperature (r.t.), under ambient condition, without encapsulation. f, V_OC versus logarithm of light intensity of the solar cells with and without DMPESI treatment with corresponding linear fits, from which the slopes determined by the ideality factors (1.38 for DMPESI and 1.74 for control) were found. k_B is the Boltzmann constant, T is the temperature and q is the elementary charge.