Title: Sustainable materials acceleration platform reveals stable and efficient wide-bandgap metal halide perovskite alloys
The vast chemical space of emerging semiconductors, like metal halide perovskites, and their varied requirements for semiconductor applications have rendered trial-and-error environmentally unsustainable. In this work, we demonstrate RoboMapper, a materials acceleration platform (MAP), that achieves 10-fold research acceleration by formulating and palletizing semiconductors on a chip, thereby allowing high-throughput (HT) measurements to generate quantitative structure-property relationships (QSPRs) considerably more efficiently and sustainably. We leverage the RoboMapper to construct QSPR maps for the mixed ion FA 1-y Cs y Pb(I 1-x Br x ) 3 halide perovskite in terms of structure, bandgap, and photostability with respect to its composition. We identify wide-bandgap alloys suitable for perovskite-Si hybrid tandem solar cells exhibiting a pure cubic perovskite phase with favorable defect chemistry while achieving superior stability at the target bandgap of 1.7 eV. RoboMapper’s palletization strategy reduces environmental impacts of data generation in materials research by more than an order of magnitude, paving the way for sustainable data-driven materials research.  more » « less
Award ID(s):
1936527
PAR ID:
10492035
Author(s) / Creator(s):
; ; ; ; ; ; ; ; ; ; ; ; ; ;
Publisher / Repository:
Cell Press
Date Published:
Journal Name:
Matter
Volume:
6
Issue:
9
ISSN:
2590-2385
Page Range / eLocation ID:
2963 to 2986
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
More Like this
  1. One of the organic components in the perovskite photo-absorber, the methylammonium cation, has been suggested to be a roadblock to the long-term operation of organic–inorganic hybrid perovskite-based solar cells. In this work we systematically explore the crystallographic and optical properties of the compositional space of mixed cation and mixed halide lead perovskites, where formamidinium (FA + ) is gradually replaced by cesium (Cs + ), and iodide (I − ) is substituted by bromide (Br − ), i.e. , Cs y FA 1− y Pb(Br x I 1− x ) 3 . Higher tolerance factors lead to more cubic structures, whereas lower tolerance factors lead to more orthorhombic structures. We find that while some correlation exists between the tolerance factor and structure, the tolerance factor does not provide a holistic understanding of whether or not a perovskite structure will fully form. By screening 26 solar cells with different compositions, our results show that Cs 1/6 FA 5/6 PbI 3 delivers the highest efficiency and long-term stability among the I-rich compositions. This work sheds light on the fundamental structure–property relationships in the Cs y FA 1− y Pb(Br x I 1− x ) 3 compositional space, providing vital insight to the design of durable perovskite materials. Our approach provides a library of structural and optoelectronic information for this compositional space. 
    more » « less
  2. Organic-inorganic halide perovskites are promising semiconductors for energy-conversion applications, but these materials face an inherent limitation due to poor intrinsic stability, particularly via decomposition upon exposure to water. The dimensionality and stability of perovskite materials are highly dependent on the organic cation in the perovskite. The incorporation of bulky organic ligands in the structure induces 2D layered perovskites where organic ligands are perpendicular to the inorganic layers and can enhance the perovskite moisture stability through the ligand hydrophobicity. Herein, the relative water stability of reportedly water-stable organic-inorganic halide perovskites were compared between microparticulate powders and compact thin films. In particular, the 3D perovskite DMASnBr3 (DMA = dimethylammonium) and 2D perovskite (PEA)2SnBr4 (PEA = phenylethylammonium) were synthesized in both forms and characterized for water stability. The microparticulate crystals of both materials exhibited significant stability in water while analogous thin films were highly unstable, which was attributed to the presence of a soluble intermixed phase. A new bulky organic ligand, 8-(2,5-bis(thiophen-2-yl)-1H-pyrrol-1-yl)-octylammonium (2TPO), with hydrophobic wing-like groups to help impede water ingress was synthesized and incorporated into a 2D perovskite structure. A thin film of (2TPO)2PbI4 exhibited strongly enhanced durability when fully immersed in water for several minutes or exposed to 85% relative humidity for several days. Material stability was characterized using techniques such as X-ray diffraction (XRD), UV-visible spectroscopy, and X-ray photoelectron spectroscopy (XPS). 
    more » « less
  3. Chalcogenide perovskite semiconductors, with their excellent optical absorption, chemical stability, and lack of toxicity, have emerged as a promising alternative to traditional halide perovskites. Through first-principles density functional theory, we show that despite the large lattice mismatch between the prototypical BaZrS3 and BaZrO3 chalcogenide perovskites, BaZr(S1−xOx)3 can form low-energy ordered lattices that significantly reduce strain. The bandgap dependence of the resulting ordered compound on x is found to exhibit double Vegard's law behavior, having two distinct linear regions, associated with an underlying distorted or undistorted perovskite structures. 
    more » « less
  4. Metal halide perovskite films in the top cell of triple-junction tandems require bandgaps around 2.0 eV to achieve current matching, assuming that the middle absorbing layer is the commonly used FAPbI3 and the bottom cell has a bandgap around 1.1 eV. Unfortunately, mixed organic/inorganic metal halide perovskites that have the necessary Br content to reach a bandgap of 2.0 eV segregate into iodine-rich and bromine-rich phases under illumination, limiting their obtainable voltage. Previous reports have shown improved photostability using either Cs-based inorganic compositions or Cl incorporation on the X-site. Here, we investigate the inorganic triple halide compositional space CsPb(I1-x-yBryClx)3 where bandgaps near 2.0 eV are expected based on the knowledge that CsPbI2Br has a bandgap of 1.90 eV. Incorporation of Cl occurs readily for x ≤ 0.07-0.10 within perovskites with a Br content of 0.3 ≤ y ≤ 0.42. When x > 0.1, x-ray diffraction and photoluminescence measurements indicate that multiple compositional phases form. We hypothesize that the variable size of the three halide ions is not supported within the rigid Cs lattice, resulting in the formation of multiple compositional phases. The photoluminescence quantum yield of the single-phase compositional space - CsPb(I1-x-yBryClx)3 where x ≤ 0.07, was typically 0.001% to 0.004%, most likely as a result of a high defect density, including mobile iodine species. Extended Photoluminescence light-soaking measurements of many perovskite compositions with bandgaps in the range of 1.89 eV to 2.05 eV demonstrate that phase segregation occurs when initial bandgaps are above 1.95 eV regardless of halide content: indicating further iodide oxidation and corresponding migration under illumination. The conclusion is that further compositional or additive engineering is necessary for the development of inorganic triple halide compositions that accomplish the elusive goal of fabricating high quality and photostable 2.0 eV films for use in multijunction tandems. 
    more » « less
  5. Halide perovskite nanocrystals are at the forefront of materials research due to their remarkable optoelectronic properties and versatile applications. While their lattice structure and optical properties have been extensively investigated for the structure–property correlation, their lattice dynamics, the physical link between the lattice structure and optoelectronic properties, has been much less visited. We report the evolution of structural dynamics of a series of cesium lead halide perovskite nanocrystals whose size and morphology are systematically varied by synthesis temperature. Low-frequency Raman spectroscopy uncovers the nanocrystals’ structural dynamics, including a relaxational spectral continuum from ligand librations and a phonon spectrum evolving with nanocrystal size. As the size of nanocrystals increases, their phonon spectrum becomes more intense, and their spectral weights redistribute with new first- and second-order modes being activated. The linewidth of the observed phonon modes generally broadens as the nanocrystal grows larger, an interesting deviation from the established phonon confinement model. We suggest that strong confinement and truncation of the lattice and ligands anchoring on the surface might lead to pinning of the lattice dynamics at nanoscale. These findings offer new insights into the bulk–nano-transition in halide perovskite soft semiconductors. 
    more » « less