Enhancement of photovoltaic performance of perovskite solar cells by modification of the interface between the perovskite and mesoporous TiO2 film

• A modification layer of SrTiO3 is introduced between CH3NH3PbI3 and TiO2.
• Better and larger crystalline growth of perovskite is achieved.
• Charge transfer is promoted from the CH3NH3PbI3 to the modified TiO2.
• The perovskite solar cell efficiency has a significant improvement of 46%.

By dipping the mesoporous TiO2 film in Sr2+ solutions and subsequent annealing, a modification layer of SrTiO3 has been formed on the surface of the mesoporous TiO2 film, and the effect of modification on the photovoltaic characteristics of the perovskite solar cells has been studied detailedly. The XPS and TEM results verified the existence and nature of the SrTiO3 modification layer. Benifiting from the TiO2 surface modification, the morphology of perovskite film and light absorption of the CH3NH3PbI3 absorber have been improved effectively, and a faster charge transfer has also been achieved between the CH3NH3PbI3 perovskite layer and the modified TiO2. As a result, an average conversion efficiency of 11.4% has been achieved in the perovskite solar cell based on the modified mesoporous TiO2 by 10 mM Sr2+ solution, and it increases approximately by 46% in comparison with the photovoltaic efficiency of 7.8% of the perovskite solar cell based the bare mesoporous TiO2 layer.

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