CsPbIBr2 Quantum Dots as an Interface Layer to Modify Perovskite CsPbIBr2 Films to Improve the Function of Solar Cells

In this paper, the effects of CsPbIBr2 quantum dots (QDs) of the same composition as perovskite films as interfacial layers on the stability, carrier dynamics, quality, and optical properties of perovskite films are investigated. CsPbIBr2 films modified by CsPbIBr2 QDs are prepared by two-step coating. Transmission electron microscopy (TEM) results show that the CsPbIBr2 QDs are formed in a lattice pattern and the size is about 10 nm. Atomic force microscopy (AFM) and surface morphology analysis (SEM) results show that when the volume of the dripped QDs is 0.08 mL, the bulk film quality is the best. To further study the effect of the QD-modified CsPbIBr2 film on the performance of PSCs, QD-modified and hole transport layer (HTL)-free all-inorganic carbon-based perovskite solar cells (PSCs) are prepared. The PCE results show that the stability and PCE of all-inorganic perovskite cells prepared with QDs as the interface layer are improved. The CsPbIBr2 carbon-based PSC prepared at a QD volume of 0.08 mL shows the best performance, for which the PCE reached 7.36%, which is 10% higher than that prepared without QD modification. This work offers a method for facilitating contacts between QDs and bulk films to achieve the high efficiency and excellent stability of HTL-free carbon-based PSCs.