Planar Perovskite Solar Cells Using Perovskite CsPbI 3 Quantum Dots as Efficient Hole Transporting Layers.

Perovskite CsPbI 3 quantum dots (QDs) were synthesized as a hole-transporting layer (HTL) of a planar perovskite solar cell (PSC). By using the Octam solution during the ligand engineering, CsPbI 3 QDs exhibits a denser grain and a larger grain size due to the short-chain ligands of Octam. In addition, CsPbI 3 QDs with the Octam solution showed a smooth and uniform surface on MAPbI 3 film, indicating the QDs improved the microstructure of the MAPbI 3 perovskite film. As a result, the PSC with CsPbI 3 QDs as an HTL has the optimal open-circuit voltage as 1.09 V, the short-circuit current as 20.5 mA/cm 2 , and the fill factor (FF) as 75.7%, and the power conversion efficiency (PCE) as 17.0%. Hence, it is inferred that introducing QDs as a HTL via the ligand engineering can effectively improve the device performance of the PSC.