Multication perovskite 2D/3D interfaces form via progressive dimensional reduction

Abstract

Many of the best-performing perovskite photovoltaic devices make use of 2D/3D interfaces, which improve efficiency and stability – but it remains unclear how the conversion of 3D-to-2D perovskite occurs and how these interfaces are assembled. Here, we use in situ Grazing-Incidence Wide-Angle X-Ray Scattering to resolve 2D/3D interface formation during spin-coating. We observe progressive dimensional reduction from 3D to n = 3 → 2 → 1 when we expose (MAPbBr3)0.05(FAPbI3)0.95 perovskites to vinylbenzylammonium ligand cations. Density functional theory simulations suggest ligands incorporate sequentially into the 3D lattice, driven by phenyl ring stacking, progressively bisecting the 3D perovskite into lower-dimensional fragments to form stable interfaces. Slowing the 2D/3D transformation with higher concentrations of antisolvent yields thinner 2D layers formed conformally onto 3D grains, improving carrier extraction and device efficiency (20% 3D-only, 22% 2D/3D). Controlling this progressive dimensional reduction has potential to further improve the performance of 2D/3D perovskite photovoltaics.

Damp heat–stable perovskite solar cells with tailored-dimensionality 2D/3D heterojunctions

“…As expected, the 2D - TA films were dominated by n = 1 layers (with a prominent peak at q z ≈ 0.35 A –1 ). In contrast, 2D-RT films exhibited the diffraction peaks of n = 1 and n = 2, with a more substantial n = 2 peak at lower q z ( 16 ). The strong intensity in the z -direction for 2D perovskite films was indicative of a highly oriented lateral direction of the top 3D perovskite layers.…”

Unveiling the additive-assisted oriented growth of perovskite crystallite for high performance light-emitting diodes

“…Various additives, including organic molecules 7 , 8 , metal halides 9 – 11 , and ammonium halides 12 – 14 , have been widely used to passivate defects in perovskite solar cells and LEDs. Apart from the defect passivation effect, additives play a key role in the crystallization process of perovskite 7 , 15 , 16 , which is also important for the resultant device performance. However, a deep understanding of how the additives influence the crystallization process of perovskites is lacking, which prevents further design of additive for high-quality perovskites.…”

Amino Acid‐Based Low‐Dimensional Management for Enhanced Perovskite Solar Cells

“…In order to improve the stability of 3D PSCs, low‐dimensional (LD) perovskites are often used. [ 28–31 ] Because of the superhydrophobicity of organic molecules, LD perovskite possesses unique advantages for improving stability. [ 32,33 ] The hydrophobic and large organic spacer cations of LD perovskites can not only prevent the penetration of water molecules into the perovskite lattice but also hinder ion motion in the perovskite film.…”

“…[26,27] In order to improve the stability of 3D PSCs, low-dimensional (LD) perovskites are often used. [28][29][30][31] Because of the superhydrophobicity of organic molecules, LD perovskite possesses unique advantages for improving…”