Fig. 1. The morphology of perovskite films with and without Cd doping.

Fig. 2. (Color online) Crystal characteristic and optoelectronic properties of perovskite films with and without Cd doping. (a) X-ray diffraction (XRD) of the perovskite films with and without Cd doing. (b) X-ray photoelectron spectroscopy (XPS) of the perovskite film with Cd doping. The Cd 3d core energy level was recorded. (c) Photoluminescence of the perovskite films with and without Cd doping. (d) Time-resolved photoluminescence (TRPL) of the perovskite films with and without Cd doping.

Fig. 3. (Color online) Device performance. (a) J–V curves of perovskite solar cells with and without Cd doping, measured under standard AM 1.5 G (100 mW/cm²). (b) External quantum efficiency (EQE) curve of the devices with and without Cd doping, the integrated short circuit current curve is also included.

Fig. 4. (Color online) Device performance distribution for the devices with and without Cd doping. The statistical distribution of (a) power conversion efficiency, (b) open circuit voltage, (c) short circuit density and (d) fill factor.

Fig. 5. (Color online) Photo-stability of the devices without and with Cd doping.

Table 1. Fitted data from TRPL spectra.