Figure 6. XRD images of a) TiO2, b) nanopatterned TiO2 layer, c) perovskite, and d) PCBM-perovskite layer.
X-ray diffraction (XRD) patterns in Figure 6 confirmed the crystallinity of nanopatterned TiO2 layer and PCBM-perovskite layer. The nanopatterned TiO2 shows anatase phase at 2θ values of 25.2˚, 37˚, 38˚, 38.5˚, 48˚, 54˚, 55˚, and 63˚, corresponding to the (101), (103), (004), (112), (200), (105), (211), and (118) peaks.[14, 24] For the PCBM-perovskite layer, the XRD patterns show that the presence of PCBM did not change the cell dimensions of the perovskite. Both pure perovskite and PCBM-perovskite layers exhibited diffraction peaks at 2θ values of 14.15˚, 20.05˚, 23.5˚, 24.6˚, 28.47˚, 31.94˚, 35.3˚, 40.66˚, and 43.12˚, corresponding to the (110), (112), (211), (202), (220), (310), (312), (224), and (314) crystal planes of tetragonal perovskite, respectively.[25] The results verified that the crystalline PCBM-perovskite was well formed on the nanopatterned TiO2 layer, thus it could achieve better ECE.