Fine control of perovskite-layered morphology and composition via sequential deposition crystallization process towards improved perovskite solar cells

• Perovskite capping layer is prepared via two-step solution-process.
• By fine control of the dipping time, ∼620 nm-thick perovskite layer is obtained.
• By optimizing mesoporous TiO2 film thickness, a PCE of 13.47% is achieved.

The ability to prepare high coverage and compact perovskite films via solution-based crystallization manipulation processes still represents a vital issue towards improving the ultimate photoelectric conversion efficiency of devices. In this work, we prepare the active perovskite layer by means of sequential deposition crystallization process i.e. dipping PbI2-infiltrated TiO2 film within CH3NH3I solution from 20s to 60s. The morphology and thickness of the as-prepared perovskite layer, and its overall performance superiority are investigated. X-ray diffraction (XRD) reveals that a maximum conversion of PbI2 to perovskite is completed upon applying a sequential deposition crystallization process of 40s. Field emission scanning electron microscope (FESEM) demonstrates that the coverage of the perovskite capping layer exhibits a trend from rise to decline in the whole dipping time from 20s to 60s. By fine control of the dipping time, a 620 nm-thickness compact perovskite active layer is obtained at the optimized dipping time of 40s and is verified to possess strong light absorption and high electron extraction efficiency, leading to a higher photocurrent. By further optimizing the mesoporous TiO2 film thickness, a high photocurrent of 23.98 mA cm−2 and an efficiency of 13.47% are achieved.

A compact and even perovskite film with a high coverage and controllable morphology is prepared via accurately manipulating the perovskite crystallization process in a sequential solution method and applied as an absorbed layer, exhibiting increased light absorption and electron extraction efficiency, and consequently an enhanced conversion efficiency of 13.47%.Figure optionsDownload as PowerPoint slide