Perovskite solar cell based on network nanoporous layer consisted of TiO₂ nanowires and its interface optimization

Abstract Anatase TiO₂ film with 3D network nanoporous structure consisted of 1D nanowires is obtained on SnO₂:F (FTO) glass substrate by in-situ hydrothermal synthesis and applied in mesoporous perovskite (CH₃NH₃PbI₃) solar cell. A thin Ti film is deposited on FTO substrate by magnetron sputtering before the hydrothermal treatment with sodium hydroxide solution. Then, a layer of network nanoporous TiO₂ (NT) film is formed. The efficiency of perovskite solar cell based on this 3D structure with one-step sintering can be optimized to 9.19%. The NT film consisted of 1D TiO₂ nanowires is beneficial to the transmission of charge carriers and the infiltration of hole transport material. And this one-step sintering process can reduce the interface defects and enhance the fill factor of the device. Then, we further optimize the surface of NT layer through TiCl₄ post-treatment. The post-treatment can optimize the carrier separation and the deposition of perovskite layer, thus improving the open-circuit voltage (V_oc) and short-circuit current density (J_sc) of perovskite solar cell. As a result, the value of J_sc gets an enhancement of 45.63% and the efficiency of perovskite solar cell reaches up to 12.78%.