The optoelectronic properties, morphology, and consequently the performance of metal halide perovskite solar cells are directly related to the crystalline phases and intermediates formed during film preparation. The gas quenching method is compatible with large‐area deposition, but an understanding of how this method influences these properties and performance is scarce in the literature. Here, in situ grazing incidence wide angle X‐ray scattering is employed during spin coating deposition to gain insights on the formation of MAPbI3 and CsxFA1−xPb(I0.83Br0.17)3 perovskites, comparing the use of dimethyl sulfoxide (DMSO) and 2‐methyl‐n‐pyrrolidone (NMP) as coordinative solvents. Intermediates formed using DMSO depend on the perovskite composition (e.g., Cs content), while for NMP the same intermediate [PbI2(NMP)] is formed independently on the composition. For MAPbI3 and CsxFA1−xPb(I0.83Br0.17)3 with a small amount of Cs (10% and 20%), the best efficiencies are achieved using NMP, while the use of DMSO is preferred for higher (30% and 40%) amount of Cs. The inhibition of the 2H/4H hexagonal phase when using NMP is crucial for the final performance. These findings provide a deep understanding about the formation mechanism in multication perovskites and assist the community to choose the best solvent for the desired perovskite composition aiming to perovskite‐on‐silicon tandem solar cells.
Perovskite solar cells (PSCs) technology is now reaching its full potential in terms of power conversion efficiency, but still presenting problems related to long‐term stability under operating conditions. One of the most promising alternatives to PSCs is the layered PSCs (2D‐PSCs). Layered perovskites present a huge compositional variety, which can be used to directly tune photophysical characteristics that influence the operational mechanisms of the devices. This review addresses the structural organization of both the organic and inorganic sublattices, focusing on how the structure influences the quantum and dielectric confinement, phonons and charge carriers' dynamics, charge mobility, and structural defects. We discuss the relation between the structure‐properties of layered perovskites with the performance of solar cells. We, then, offer insights into how these characteristics have been controlled in the assembly of 2D‐PSCs to improve their efficiency and stability. We conclude by giving a perspective of future developments and open areas of exploration that might impact the progress of this rapidly growing technology.
Hybrid organic and inorganic perovskite solar cells lack long‐term stability, and this negatively impacts the widespread application of this emerging and promising photovoltaic technology. Herein, aiming to increase the stability of perovskite films based on CH3NH3PbI3 and to deeply understand the formation of 2D structures, solutions of alkylammonium chlorides containing 8, 10, and 12 carbons are introduced during the spin‐coating on the surface of 3D perovskite films leading to the in situ formation of 2D structures. It is possible to identify the chemical formulae of some 2D structures formed by X‐ray diffraction and UV–vis analysis of the modified films. Interestingly, the increase in the stability of the CH3NH3PbI3 films due to the formation of a 2D + 3D perovskite network is only possible in planar TiO2 substrates. The increase in stability of the CH3NH3PbI3 films follows the surfactant molecule order: octylammonium (8C) > decylammonium (1 °C) > dodecylammonium (12C) chlorides > standard. An increase of 17.6% in the lifetime of the devices assembled with octylammonium‐modified perovskite film is observed compared with that of the standard device, which is directly linked to the improvement of the charge carrier lifetimes obtained from time‐correlated single photon counting measurements.
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