X-ray diffraction (XRD) was performed on a X-ray diffractometer
(D8-Advance, Bruker, Germany) using Cu Ka radiation
(= 1.5406Å) at step size/time of 0.06◦/s. The surface and
cross-sectional morphology were observed using a field emission
scanning electron microscope (FE-SEM, HITACHI SU-4800).Steady-state photoluminescence spectroscopy (PL) measurements
were acquired using an Edinburgh Instruments FLS920 fluorescence
spectrometer with an excitation wavelength of 460 nm. The
absorption spectra of the perovskite coated films were measured
by using a Cary 500 UV–vis-NIR Spectrophotometer. The current
density-voltage (J-V) measurements were conducted under simulatedAM1.5
G sunlight of 100 mW/cm2 using anAM1.5 G type filter
(Newport, USA). The light intensity was adjusted by using a standard
Si cell. J-V curves were recorded with a Keithley model 2400
digital source meter at room temperature in the ambient air with
humidity of 40–60%. A typical active area of 0.15 cm2 was confined
using a non-reflective mask for the J-V measurements.