CsPbI₃/PbSe Heterostructured Nanocrystals for High-Efficiency Solar Cells

Colloidal cesium lead iodide (CsPbI₃) perovskite quantum dots (QDs) are promising materials for solar cells because of their suitable optical bandgap and the ease of solution-based processing into large-area films. Herein, we report a synthetic strategy to build up a colloidal CsPbI₃/PbSe heterostructure, which not only improves the absorption of sunlight but also passivates the surface of perovskite QDs, which results in a lower trap density and prolonged exciton lifetimes. Moreover, the presence of the PbSe component modifies the electronic properties of the composite films, by changing the CsPbI₃ QD film from n-type to more ambipolar behavior, thus helping to promote carrier separation and collection. These improvements result in high-performance CsPbI₃/PbSe QD solar cells with a power conversion efficiency of 13.9% and improved storage stability against moisture, benefiting from the hydrophobic protective coating resulting from the presence of PbSe component.