Cr2O3 interlayer at TiO2/perovskite interface propelling the efficiency improvement of perovskite solar cells

In perovskite solar cells, charge loss and carrier recombination at interfaces are crucial factors to photovoltaic performance. In this report, Cr2O3 layer is introduced between TiO2 electron transport layer and perovskite light absorption layer. The modified device achieves an improved power conversion efficiency of 18.51% compared to the value of 17.10% for the control device. For one thing, the enhanced photovoltaic performance can be attributed to the cascade conduction band structure of TiO2/Cr2O3 bilayer. Cr2O3 is a kind of wide bandgap semiconductor. Its energy level matches very well with TiO2 ETL and perovskite light-absorption layer so as to it can work as a barrier to retard electrons from TiO2 layer reversely transport, impeding charge carrier recombination. For another, Cr2O3 interface layer can effectively avoid the direct contact of perovskite and bottom conductive electrode, reducing current leakage and carrier recombination. Both of these advantages lead to better photovoltaic performance. The work exhibits that Cr2O3 can be an efficacious interlayer material in perovskite solar cells.