Application of mesoporous SiO2 layer as an insulating layer in high performance hole transport material free CH3NH3PbI3 perovskite solar cells

• Mesoporous SiO2 is prepared by spin-coating.
• SiO2 layer can act as an efficient insulating layer.
• Higher power conversion efficiency is obtained with TiO2/SiO2 films.

A mesoporous SiO2 layer is successfully introduced into the hole transport material free perovskite solar cells by spin-coating a SiO2 paste onto the TiO2 scaffold layer. This SiO2 layer can act as an insulating layer and effectively inhibit the charge recombination between the TiO2 layer and carbon electrode. The variation of power conversion efficiencies with the thickness of SiO2 layer is studied here. Under optimized SiO2 thickness, perovskite solar cell fabricated on the TiO2/SiO2 film shows a superior power conversion efficiency of ∼12% and exhibits excellent long time stability for 30 days.