High-Performance Perovskite Solar Cells with a Weak Covalent TiO2:Eu3+ Mesoporous Structure

Mesoporous TiO2 nanocrystals with attached Eu3+ ions in an amorphous state are employed as structures for highly efficient perovskite solar cells. The down-conversion TiO2:Eu3+ nanocrystal shows a good photoluminescence characteristic to convert the incident high-energy photon into a lower-energy photon, which improves the UV light utilization capability of perovskite solar cells (PSCs). The device within 1.0 wt % Eu3+ ions shows an improvement of 29.2% from 12.22% to 15.79% in PCE compared with the typical devices without Eu3+ in TiO2, which is attributed to the increased utilization of incident UV light and the dramatically suppressed electron recombination process. To summarize, the combination of a high UV light-harvesting capability and a slow electron recombination process with TiO2:Eu3+ mesoporous structure could successfully develop more efficient and stable PSCs.