Large Area Perovskite Solar Cells With High Short-circuit Current Density Based On Tantalum-doped TiO₂ Nanorods

Our group has reported the highest efficiency of perovskite solar cells based on TiO2 nanorods.In this paper,based on this structure,we modified TiO2 nanorods by doping Ta to improve the short current of solar cells,and we also changed the preparation method of perovskite from one-step spin coating to two-step spin coating,and achieved the best efficiency of 13.11%in 1x1 cm2 active area.Fistly,we successfully prepared the Ta doped TiO2 nanotubes,and discuused the effect of Ta doping on the energy level of TiO2 nanotubes.As the morphology of TiO2 nanorods will affect the efficiency of cells and the Ta doping can change the morphology of TiO2 nanorods,we controled the concentration of Ta and the reaction time to ensure similar morphology before and after doping.Under the synergistic effect of Ta5+ 5d orbit and oxygen vacancy,the conduction band position tended to decrease first and then increase with the increase of doping concentration.Secondly,a two-step spin-coating process was carried out on the perovskite layer.The placement time of the lead iodide film,the concentration of the methylamine salt and the spin-coating speed were adjusted to form homogeneous perovskite film without iodide lead phase.Finally,we fabricated the solar cells based on Ta doped TiO2 nanorods.The J-V showed that when the Ta concentration was less than 0.1%,the Jsc gradually increased and the Voc gradually reduced.When the Ta doping concentration was greater than 0.1%,the Jsc decreased,and the Voc increased.0.1%Ta doping achieved the highest efficiency of 13.11%in 1x1 cm2 active area.The Ta doping also could improve the stability of device,the device PCE remained at 92%of the initial value after 1000 h of atmospheric storage.