Fig. 1. (Color online) (a) XRD spectra obtained from perovskite films. Top-view SEM images of perovskite films with (b) control, (c) OAI, (d) PEAI, and (e) PEAI + OAI bilayer passivation on perovskite films.

Fig. 2. (Color online) (a) UV−vis spectra of different perovskite films. (b) Corresponding band gap was calculated using Tauc plots. (c) PL spectra and (d) TRPL spectra of different passivation treatments on the perovskite layer. Black, red, blue, and green lines represent control, OAI, PEAI, and PEAI + OAI bilayer, respectively.

Fig. 3. (Color online) (a)−(d) UPS spectra of secondary electron cutoff and valence band of the control and PEAI + OAI modified perovskite films. (e) Energy-level scheme based on the parameters calculated from UPS spectra.

Fig. 4. (Color online) (a) Pb 4f and (b) I 3d core-level XPS spectra of different surface passivation schemes.

Fig. 5. (Color online) (a) J−V curves of the PSCs fabricated with different passivation layers. Statistical distribution of optoelectronic performance of surfaces treated with different passivation layers: (b) V_OC, (c) FF, (d) J_SC, and (e) PCE.

Fig. 6. (Color online) The response of devices under different light intensities for the control, OAI, PEAI, and PEAI + OAI treated devices. (a) J−V curves of the devices under dark conditions. (b) J−V curve of the PEAI + OAI bilayer treatment champion cells under different light intensities. Linear relationship of (c) V_OC and (d) J_SC with the light intensity.

Fig. 7. (Color online) (a) XRD patterns of the control and PEAI + OAI bilayer modified perovskite film after storing under ambient conditions with 25 °C and 30 ± 10% RH for 14 days. Water contact angle measurements of (b) control, and (c) PEAI + OAI bilayer modified films (The inserted images are optical photos after 14 days of age).