Lead‐Doped Titanium‐Oxo Clusters as Molecular Models of Perovskite‐Type PbTiO3 and Electron‐Transport Material in Solar Cells

In this work we have successfully prepared two lead‐doped titanium‐oxo clusters with core structures that resemble isolated perovskite PbTiO3 species. In the obtained highly symmetric Pb8Ti7‐oxo cluster, the central TiO6 octahedra are orthogonally extended to adjacent octahedra through corner‐sharing and the eight dopant lead ions form a cubic arrangement, making it the first molecular model of perovskite PbTiO3. Moreover, the clusters readily dissolved in chloroform and showed high solution stability, as confirmed by MALDI‐TOF MS measurements. Based on such solution processability, they can be easily spin‐coated to form homogeneous films, which were employed as electron‐transport materials in perovskite solar cells to give an average power conversion efficiency of around 15 % and improved device stability. This newly developed bottom‐up cluster assembly method provides an efficient approach to the construction of atomically precise models of perovskite metal oxides as well as potential molecular tools to extend their applications. Outstanding resemblance! The first molecular model of perovskite PbTiO3 has been successfully prepared by bottom‐up assembly of lead‐doped titanium‐oxo clusters in the presence of p‐tert‐butylthiacalix[4]arene as stabilizing ligands. Structural characterization confirmed that the clusters have almost the same structure as that in PbTiO3 (see figure). The nanoclusters showed high solution stability and can be applied as electron‐transport materials in perovskite solar cells to give satisfactory efficiencies and high device stability.