Facile synthesis of ordered Nb2O5 coated TiO2 nanorod arrays for efficient perovskite solar cells

Abstract Reducing defect density and hindering charge recombination in perovskite film and at perovskite/semiconductor interface are crucial to perovskite solar cells (PSCs) performance. In this paper, hydrothermally prepared TiO2 nanorod arrays (TNRAs) were coated with Nb2O5 layer using a spin-coating method, and the modified TNRAs were used as scaffold for the deposition of perovskite films and corresponding PSCs in air environment. The effect of NbCl5 concentration on the micro structure and photovoltaic properties of the formed perovskite films were investigated, and the enhancement mechanism was also elucidated. A champion efficiency of 16.50% (enhanced of 9.49% compared with the pristine one) was achieved when the concentration of NbCl5 solution was 0.005 M. Such an enhanced performance of PSC might be mainly ascribed to two reasons: one was the improved perovskite film qualities including the enlarged average grain size, higher crystallinity and reduced defect density; the other was the formed energy barrier (Nb2O5) between perovskite layer and TNRAs interface that hindered the charge recombination.