Crystal Growth and Dissolution of Methylammonium Lead Iodide Perovskite in Sequential Deposition: Correlation between Morphology Evolution and Photovoltaic Performance

Abstract

Crystal morphology and structure are important for improving the organic-inorganic lead halide perovskite semiconductor property in optoelectronic, electronic, and photovoltaic devices. In particular, crystal growth and dissolution are two major phenomena in determining the morphology of methylammonium lead iodide perovskite in the sequential deposition method for fabricating a perovskite solar cell. In this report, the effect of immersion time in the second step, i.e., methlyammonium iodide immersion in the morphological, structural, optical, and photovoltaic evolution, is extensively investigated. Supported by experimental evidence, a five-staged, time-dependent evolution of the morphology of methylammonium lead iodide perovskite crystals is established and is well connected to the photovoltaic performance. This result is beneficial for engineering optimal time for methylammonium iodide immersion and converging the solar cell performance in the sequential deposition route. Meanwhile, our result suggests that large, well-faceted methylammonium lead iodide perovskite single crystal may be incubated by solution process. This offers a low cost route for synthesizing perovskite single crystal.

Europium and Acetate Co‐doping Strategy for Developing Stable and Efficient CsPbI2Br Perovskite Solar Cells

“…The morphology of perovskite film is crucial for improving the performance of photovoltaic devices . In order to further investigate the effects of Eu(Ac) 3 dopant on CsPbI 2 Br pervoskite films, the morphology of CsPbI 2 Br perovskite films were observed by scanning electron microscopy (SEM), as shown in Figure a–e.…”

Substitutional Growth of Methylammonium Lead Iodide Perovskites in Alcohols

“…The reaction does not produce a high MAPbI 3 yield when the mass concentration of solution is <40 wt% as tested in methanol ( Figures S31 and S32, Supporting Information). [27] Tetragonal phase at (110) is achieved only under this reaction condition along without any residual precursors ( Figures S8 and S9f, Supporting Information). The shift of the XRD peak at 2θ ≈ 19.8° for the (112) orientation is observed only at 60 °C after 48 h and is a signature of the perovskite conversion in solution.…”

“…MAPbI 3 growth in ethanol (75 °C for 48 h) shows increased X-ray intensity of the peak at 2θ ≈ 28°-28.5° that corresponds to preferable growth direction at (004) and (220) (Figures S10-S12f, Supporting Information). [31] In contrast, the ratio of the (004/220) peak to the (222/310) peak is 1 for MAPbI 3 growth in 2-butanol ( Figure S16c, Supporting Information), and the (110) peak has the maximum X-ray intensity, representing platelet-like grains (Figure 5v). SEM images show that (004/220) preferable growth direction results in cubicshaped crystals ( Figure 5,ii-iv) for MAPbI 3 growth in ethanol, 2-propanol, and 1-butanol.…”

“…For SEM (Figure 5), MAPbI 3 dispersions are spin coated on carbon tape ( Figures S28 and S29, Supporting Information) without sonication. The binding affinity of alcohols and reaction temperature determine the morphology of the resulting MAPbI 3 grains, [27] Spectral deconvolutions constrained to the line shape observed for the toluene material. The crystals from ethanol are ≤10 µm ( Figure 5ii) and are mostly in the 200 nm up to 1 µm range, for 2-propanol ≥1 µm with small crystals mostly between 200 and 500 nm, and for 1-butanol in the 100-500 nm range, respectively (Figure 5iii,iv).…”

“…The largest grain size is obtained for methanol (≥10 µm in Figure 5i), while the grain size is substantially smaller for MAPbI 3 derived from all other alcohols. [27,28] The grain size of crystals are correlated by comparison of the full width half-maximum (FWHM) the (110) preferred growth direction (Figures S8-S16, Supporting Information). The binding affinity of alcohols and reaction temperature determine the morphology of the resulting MAPbI 3 grains, [27] Spectral deconvolutions constrained to the line shape observed for the toluene material.…”