Figure 7. FTIR of a) FTO, b) perovskite/FTO, c) PCBM/FTO, and
d) PCBM-perovskite/FTO.
To elaborate on the information of the PCBM-perovskite layer, FTIR
spectroscopy was carried out and the results are as shown as inFigure 7. Figure 7 shows the comparison between the FT-IR
spectra of a) FTO, b) perovskite/FTO, c) PCBM/FTO, and d)
PCBM-perovskite/FTO. The peaks at 3200 and 3100 cm-1are due to the N-H stretching vibration for primary amines, and the 1600
and 1475 cm-1 double bands belong to the C=C group.
The C-N stretching absorption that occurs in the region from 1250-1000
cm-1 indicates the aliphatic
amines[26] while the single band at 900
cm-1 is corresponding to the metal iodide stretching
vibration,[27] as shown in Figure 7b.
Apart from that, the incorporation of PCBM in the PCBM-perovskite layer
was confirmed by comparing Figure 7c and 7d. The absorption bands for
PCBM can be observed near 3000 cm-1, which indicates
the sp3 C-H absorption of alkanes group while the
absorption bands for C=O and C-O that appear within the range of
1750-1735 and 1300-1000 cm-1 indicate that the
compound is an ester. The peak at 1465 cm-1 is due to
the CH2 bending absorption, which is the characteristic
of methylene group[26] and the peak at 524
cm-1 belongs to
C60.[28] It can be seen that the
main characteristic peaks of perovskite and PCBM can be identified in
Figure 7d, which indicate the good formation of the PCBM-perovskite
layer.