To improve the efficiency of perovskite solar cells, careful device design and tailored interface engineering are needed to enhance optoelectronic properties and the charge extraction process at the selective electrodes. Here, we use two-dimensional transition metal carbides (MXene Ti3C2Tx) with various termination groups (Tx) to tune the work function (WF) of the perovskite absorber and the TiO2 electron transport layer (ETL), and to engineer the perovskite/ETL interface. Ultraviolet photoemission spectroscopy measurements and density functional theory calculations show that the addition of Ti3C2Tx to halide perovskite and TiO2 layers permits the tuning of the materials’ WFs without affecting other electronic properties. Moreover, the dipole induced by the Ti3C2Tx at the perovskite/ETL interface can be used to change the band alignment between these layers. The combined action of WF tuning and interface engineering can lead to substantial performance improvements in MXene-modified perovskite solar cells, as shown by the 26% increase of power conversion efficiency and hysteresis reduction with respect to reference cells without MXene.
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The experimental data that support the findings of this study are available from the corresponding author upon reasonable request.
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A.D.C. and D.S. gratefully acknowledge the financial support from the Ministry of Education and Science of the Russian Federation in the framework of MegaGrant (no. 075-15-2019-872 (14.Y26.31.0027/074-02-2018-327)). A.A. and S.P. gratefully acknowledge funding from the European Union’s Horizon 2020 Research and Innovation Program (grant agreement no. 785219-GrapheneCore2).
The authors declare no competing interests.
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Agresti, A., Pazniak, A., Pescetelli, S. et al. Titanium-carbide MXenes for work function and interface engineering in perovskite solar cells. Nat. Mater. 18, 1228–1234 (2019). https://doi.org/10.1038/s41563-019-0478-1
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