Electric field enhanced with CdS/ZnS quantum dots passivation for efficient and stable perovskite solar cells

Abstract

The potential loss caused by defects is one of the most important factors affecting the performance of perovskite photovoltaic devices. CdS/ZnS quantum dots (QDs) have good hydrophobicity and can achieve the dual effects of waterproofing hydrophobic and defect passivation of perovskite films. The Lowest Unoccupied Molecular Orbital (LUMO) energy level of CdS/ZnS QDs doped perovskite film decreases from −3.75 eV to −3.85 eV. The barrier of photo-generated charge transport from the perovskite layer to the electron transport layer is significantly reduced, which is conducive to the enhancement of built-in potential. The density of trap states is reduced and the non-radiative recombination of carriers is suppressed. CdS/ZnS QDs doped perovskite film is dense and has a lower roughness, which helps to increase the contact area with the electron transport layer, thereby improving the charge transportation. Finally, the highest efficiency of the device with QDs reaches 21.36%, and the open-circuit voltage (Voc) and the short-circuit current density (Jsc) are significantly increased compared with undoped ones. The hydrophobicity and stability of the device have also been improved. Therefore, the effect of CdS/ZnS QDs on passivation may provide new ideas for the efficient and stable perovskite solar cells.