Revealing the Perovskite Film Formation Using the Gas Quenching Method by In Situ GIWAXS: Morphology, Properties, and Device Performance

Abstract

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.

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

“…We sought to gain insight into the formation mechanism of 2D/3D interfaces using in situ grazing-incidence wide-angle X-ray scattering (GIWAXS), which can inform on the orientation and d-spacing of any diffractive species that form during the spin-coating of the ligand solution. In situ GIWAXS has been used previously to study the formation of 2D or 3D perovskites directly from precursors in solution, tracking the formation of intermediate states and precursor complexes that eventually transform into perovskite [18][19][20][21] . Here we instead use this technique to probe the transformation of the already fully-formed 3D perovskite surface into RDPs, by collecting diffraction patterns before, during, and after exposure of the 3D perovskite to a solution containing 2D ligand cations.…”

Rapid hybrid perovskite film crystallization from solution

“…Additionally, the reduction of solubility can be performed by the gas flow on the crystallization process. [104][105][106] The way of reaching the supersaturation can determine several crystal features such as size, morphology, and coexisting atomic structures. 107 Nevertheless, this review focuses on liquid room temperature solvent cases.…”

A Review on Gas‐Quenching Technique for Efficient Perovskite Solar Cells

“…Recently, Szostak et al also used NMP as the solvent in the gas-quenching technique, revealed the perovskite film formation, and analyzed the evolution of crystalline phases and intermediates during film preparation. [59] They compared the film-forming processes of MAPbI 3 and Cs x FA 1Àx Pb(I 0.83 Br 0.17 ) 3 perovskite components synthesized with DMSO and NMP as precursor solvents, demonstrating that the film-forming process depends on the composition of perovskite. As shown in Figure 4a,b, for MAPbI 3 perovskite, the presence of the intermediate MA 2 Pb 3 I 8 •2DMSO leads to pinholes in the films so that the PCE is only 9.9%, whereas the NMP-based films reveal pinholefree and good coverage, so it exhibits superior PCE of 16.4%.…”

“…[42][43][44][45][46][47][48][49][50][51][52][53][54][55][56][57] Among these crystallization methods, gas quenching is a desirable technique for the fabrication of large-area perovskite films, which can be easily integrated into a production line by coupling upscalable methods such as slot-die coating or roll-to-roll printing with an air knife, providing great potential for fabricating large-scale perovskite solar cells. [58][59][60][61][62][63][64] Based on the above advantages, gas quenching has strong competitiveness and wide application, which will boost the development of perovskite solar cell technology moving from the laboratory to the market.…”