Crystallisation control of drop-cast quasi-2D/3D perovskite layers for efficient solar cells

Abstract

Introducing layered quasi-2D perovskite phases into a conventional 3D perovskite lightabsorbing matrix is a promising strategy for overcoming the limited environmental stability of 3D perovskite solar cells. Here, we present a simple drop-casting method for preparing hybrid perovskite films comprising both quasi-2D and quasi-3D phases, formed using phenylethylammonium or iso-butylammonium as spacer cations. The film morphology, phase purity, and crystal orientation of the hybrid quasi-2D/3D perovskite films are improved significantly by applying a simple N 2 blow-drying step, together with inclusion of methylammonium chloride as an additive. An enhanced power conversion efficiency of 16.0% is achieved using an isobutylammonium-based quasi-2D/3D perovskite layer which, to our knowledge, is the highest recorded to date for a quasi-2D/3D perovskite solar cells containing a non-spin-cast perovskite layer prepared under ambient laboratory conditions.

Crystallization Kinetics in 2D Perovskite Solar Cells

“…Recently, researchers found that the introduction of long‐chain organic cations in 3D perovskite as 2D perovskite can block water and oxygen molecules, meanwhile, generate a steric effect to prevent phase transitions, and limit ion migration. [ 34–36 ] Hence, fabricating 2D [ 37,38 ] or 2D/3D [ 39–43 ] mixed perovskite as absorbing layers are effective approaches to improve the stability of PSCs. However, the PCE of 2D PSCs remain lower than that of the 3D ones, which is mainly attributed to the introduction of organic macromolecules that blocks the effective extraction and transport of carriers.…”

Drop‐Casting to Make Efficient Perovskite Solar Cells under High Humidity

“…[20][21][22] Drop-cast MAPbI 3 films consisted of needle-like crystals, leading to low device performance. [19] Improving the morphology of drop-cast MAPbI 3 films is an effective way to realize higher device performance. In this work, we regulate the growth of MAPbI 3 crystals in the film made by dropcasting.…”

“…Recently, we prepared two‐dimensional (2D) Ruddlesden–Popper perovskite films by using drop‐casting [18, 19] . This method was performed in air, and it is suitable for in situ study of crystal growth.…”

“…This method was performed in air, and it is suitable for in situ study of crystal growth. The PCE for drop‐cast Ruddlesden–Popper perovskites is low (16 %) due to the complicated phase distribution in the film [19–21] . 3D MAPbI 3 perovskite made by spin‐coating gave a much higher PCE than the 2D perovskites [20–22] .…”

“…3D MAPbI 3 perovskite made by spin‐coating gave a much higher PCE than the 2D perovskites [20–22] . Drop‐cast MAPbI 3 films consisted of needle‐like crystals, leading to low device performance [19] . Improving the morphology of drop‐cast MAPbI 3 films is an effective way to realize higher device performance.…”