Fig. 1. (Color online) (a) Three-dimensional chemical structure of EDO. FTIR spectra of (b) C=O bonds and (c) N−H bonds of Pb−Sn perovskite precursor solutions. Control and target perovskite XPS spectra of (d) Sn 3d, (e) Pb 4f, and (f) I 3d . (g) Schematic illustration of the interaction of perovskite with EDO.

Fig. 2. (Color online) (a) XRD patterns of control and EDO-modified films. Cross-section SEM images of (b) control and (c) target perovskite films, Top-view SEM images of (d) control and (e) target perovskite films, AFM images of (f) control and (g) EDO-modified films. KPFM images of (h) control and (i) EDO-modified films.

Fig. 3. (Color online) XPS spectra of (a) control and (b) EDO-modified films. (c) PL spectra and (d) TRPL spectra of Pb–Sn perovskite films without (control) and with EDO (target) treatment. (e) Dark J−V curves of representative control and target. (f) Mott−Schottky plots of control and target. (g) Dependence of V_oc on light intensity for control and target. (h) Electronic impedance spectroscopy (EIS) plots of control and target. (i) SCLC curves of control and target hole-only devices.

Fig. 4. (Color online) (a) Device architecture of single junction NBG PSCs. (b) J–V curves and (c) EQE curves. (d) Steady-state power outputs. (e) Stability performance of PSCs under continuous light illumination.

Fig. 5. (Color online) (a) Device architecture of 2T all-perovskite tandem solar cells. (b) Cross-sectional SEM image, (c) J−V curves, (d) EQE curves, (e) steady-state power outputs. (f) Histogram of PCEs for 10 tandem cells.