Cadmium and ytterbium Co-doped TiO2 nanorod arrays perovskite solar cells: enhancement of open circuit voltage and short circuit current density

TiO 2 nanorod arrays of crystalline Cd, Y-co-doped rutile were synthesized and successfully assembled in perovskite solar cells (PSCs) as the photoanode. In this work, CH 3 NH 3 PbI 3−x Cl x was used as the light absorber and spiro -OMeTAD as hole transport material (HTM). The synthesized TiO 2 nanorod arrays were investigated by field emission-scanning electron microscopy (FE-SEM), X-ray powder diffraction (XRD) and UV–Vis diffused reflectance. FE-SEM images indicate that the co-doped TiO 2 nanorod arrays were slightly sparser and shorter in length than that of un-doped ones. XRD pattern demonstrates that the as-prepared TiO 2 nanorod arrays were rutile phase. The UV–Vis spectrum proves that the co-doped samples possess higher light scattering intensity than the un-doped samples, which may contribute to improve the short current density of PSCs. And the band gap of the TiO 2 nanorod shows a positive shift when doped with cadmium and ytterbium. Furthermore, a negative shift in the flat-band potential (V fb ) was also observed. Finally, the device based on co-doped TiO 2 nanorod arrays has improved open circuit voltage (V oc ) and short circuit current density (J sc ). A higher power conversion efficiency (η) of 9.06% was obtained for the co-doped device while 8.12% for the un-doped TiO 2 nanorod arrays. This paper opens a door to multi-element co-doped 1-D nanostructured materials for the improving the open circuit voltage and short circuit current density of perovskite solar cells.