Efficient All-Inorganic CsPbBr3 Perovskite Solar Cells by Using CdS/CdSe/CdS Quantum Dots as Intermediate Layers

Highly efficient all-inorganic perovskite solar cells require a fast charge transfer from CsPbBr3 to TiO2 to reduce the recombination from trap states. Herein, we insert a CdS/CdSe/CdS quantum dot (QD) layer between the TiO2 and CsPbBr3 layers to fabricate all-inorganic perovskite solar cells. By tuning the thicknesses of the CdSe layer of CdS/CdSe/CdS QDs, the conduction band (CB) levels can be adjusted to -3.72-3.87 eV. After inserting the QD intermediate layer, the energy offset between the CB of TiO2 and CsPbBr3 is reduced, thus leading to a charge transfer rate boost from 0.040x109 to 0.059x109 s-1. The power conversion efficiency (PCE) of the solar cell with QD intermediate layer achieves 8.64%, which is 20% higher than its counterpart without QDs.