Regulating Radial Morphology in Hot-Casting Two-Dimensional Ruddlesden–Popper Perovskite Film Growth for High-Efficient Photovoltaics

Abstract

Two-dimensional (2D) perovskites have attracted significant attention in recent years due to their promising light harvesting and emissive properties. However, the realization of 2D perovskite crystallization with sufficient coverage and reliable reproducibility remains difficult. In this study, controlling the solvent volatilization to achieve high-quality crystallization with full coverage and lateral homogeneity of 2D Ruddlesden–Popper phase perovskite was effectively achieved. It is found that variations in the solvent evaporation rate give rise to lateral film coverage gradients with the degree of grain fusion during the process of hot-casting. As a result, the obtained photovoltaic efficiency varies due to the growth inhomogeneity across hot-casting thin films from center to edge. By adjusting the temperature of the casting perovskite precursor, film inhomogeneity and device performance variation can be alleviated. Regulating radial morphology across hot-casting thin films will enable coating techniques amenable to the solution process for robust reproducibility.

Additive Engineering for Stable and Efficient Dion–Jacobson Phase Perovskite Solar Cells

“…Prior research has shown that adding large or long-chain monovalent organic cations [ 11 ], for example C 4 H 9 NH 3 + [ 12 – 15 ], to create two-dimensional (2D) Ruddlesden–Popper (RP)-layered halide perovskite phases [ 11 , 16 ] is a useful method for boosting the chemical steadiness of halide perovskites (PVK). Even though these materials appear to have better chemical stability in a variety of environmental settings [ 5 , 17 ], their photovoltaic performance is typically worse than that of three-dimensional (3D) halide PVK [ 18 , 19 ], primarily because the intrinsic van der Waals gap hinders carrier transport across the long organic spacers [ 20 – 23 ].…”

Vertical Halide Segregation and Stability of Two-Dimensional Layered Perovskite Nanostructures: Implications for Optoelectronic Devices

“…Previous research indicates that quasi-2D perovskite films prepared by one-step hot casting typically consist of multiple vertically arranged perovskite phases, with the small- n phase predominantly located at the bottom (film/substrate interface) and the large- n phase occupying the top region (film/air interface) of the films . This bottom-up growth of the perovskite phase is primarily attributed to the uneven heating of the substrate and the evaporation of residual solvent from the top surface of the “wet” film. , However, this uneven phase distribution hampers carrier transport and undermines the device performance and stability. Improving the gradient distribution of 2D perovskites can significantly enhance the performance of solar cells.…”

“…42 This bottom-up growth of the perovskite phase is primarily attributed to the uneven heating of the substrate and the evaporation of residual solvent from the top surface of the "wet" film. 43,44 However, this uneven phase distribution hampers carrier transport and undermines the device performance and stability. Improving the gradient distribution of 2D perovskites can significantly enhance the performance of solar cells.…”