摘要
Perovskite solar cells have attracted much attention recently because of their high conversion efficiency enabling to fabricate at low-cost solution-based process. However, the high-quality perovskite via two-step sequential deposition hinges on the morphological structure of lead iodide (PbI 2 ) that directly affects its conversion into the perovskite. Herein, we demonstrate a facile approach to optimize the quality of two-step sequential perovskite by manipulating the morphology of PbI 2 via the utilization of hydrothermally synthesized TiO 2 nanorod arrays as the underlying layer. Our result reveals that the nanorod-shaped TiO 2 arrays composed of inter-nanorod spaces can offer an improved wettability to the solution-based PbI 2 coating. The variation of inter-nanorod spaces with TiO 2 nanorod lengths plays a crucial role in attaining the morphology of PbI 2 film with tunable porous structure, facilitating the interfacial reaction with methylammonium iodide. The perovskite solar cell formed on the proper TiO 2 nanorod arrays can deliver a better device performance than that of the improper counterparts, leading to the increase of the conversion efficiency from 11.98% to 13.05%. Such a boosted result from the optimized underlying layer can be ascribed for the improvement of the surface roughness and the converted process of PbI 2 , beneficial for achieving a high-quality perovskite film.