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

• 3D TiO2 network nanoporous structure consisted of 1D nanowires is fabricated on FTO.
• One-step sintering can reduce the interface defects and enhance the fill factor.
• A novel in-situ method is studied for the preparation of porous scaffold layer.
• The new 3D porous scaffold layer is superior to TiO2 nanoparticle film.
• The efficiency of perovskite solar cell based on this structure reaches up to 12.78%.

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 (Voc) and short-circuit current density (Jsc) of perovskite solar cell. As a result, the value of Jsc gets an enhancement of 45.63% and the efficiency of perovskite solar cell reaches up to 12.78%.