Modified post-annealing process with N, N-dimethylformamide vapor to control the growth of hybrid perovskite microstructure

Abstract

The post-annealing treatment condition has a great impact on the orientation and growth of perovskite phases. In this study, the formation of CH3NH3PbI3 films was controlled using different post-annealing processes, including a modified N, N-dimethylformamide (DMF) vapor treatment. Field-emission scanning electron microscopy (FE-SEM), and X-ray diffraction (XRD) were used to characterize the microstructure of the perovskite films. An appropriate amount of DMF with a modified post-annealing setup dramatically improves the properties of the perovskite films, whereas an excess amount of DMF solvent leads to poor coverage and degraded films. The average grain size of the modified setup solvent-annealed perovskite film with 100 μL of DMF at 100 °C for 10 min reached ≈1.84 μm, almost five times larger than the mere 0.427 μm of the only thermally annealed at 100 °C for 10 min CH3NH3PbI3 film. The devices fabricated with the films with modified DMF vapor treatment showed improved photovoltaic performance, providing insight into the formation mechanism, and an effective method to improve the film quality of perovskite for photovoltaic application.

Keywords

• Post-annealing condition
• Hybrid perovskite
• Microstructure
• Vapor-assisted annealing
• Grain growth