First-principles analysis of the optical properties of lead halide perovskite solution precursors

Procida, Giovanni; Schier, Richard; Valencia, Ana M.; Cocchi, Caterina

doi:10.1039/d1cp03574f

Cited by 5 publications

(19 citation statements)

References 61 publications

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“…Despite the simplicity of these synthetic methods, there has been a myriad of other reported synthesis methods, ,− for example, using other solvents and various additives, which altogether suggest that much of this work has been done without an in-depth understanding of the impacts of solvents, solvent–solute interactions, and various additives. Recently, several computational studies have attempted to characterize metal halide precursor solutions with a particular focus on lead halide perovskites. − Investigations and understanding of the precursor solution chemistry are expected to result in optimized syntheses of high-quality lead halide perovskites.…”

Section: Introductionmentioning

confidence: 99%

Investigation of the Solution Chemistry of Hybrid Organic–Inorganic Indium Halides for New Material Discovery

et al. 2022

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Recently, metal halide perovskites (MHPs) have emerged as a new class of materials for optical and electronic applications such as solar cells and ionizing radiation detectors. Although the solution-processability of MHPs is among their greatest advantages, the solution chemistries of most metal halide systems and their relationship with the observed structural and chemical diversity are poorly understood. In this work, we study the solution chemistry of a model indium halide system, methylammonium (MA)−In−Br, using a combination of the UV−vis spectroscopy, electrospray ionization mass spectrometry (ESI-MS) measurements, small-angle X-ray scattering (SAXS), and density functional theory (DFT) calculations. Our results show that indium could form either octahedral [InBr 6 3− ] or tetrahedral [InBr 4 − ] anions in solution or a combination of both, depending on the loading ratios of MABr and InBr 3 reactants. Understanding the solution chemistry of this system and recognizing the optical fingerprints of these polyanions allow for targeted crystallization of two novel compounds: MAInBr 4 featuring tetrahedral [InBr 4 − ] anions and MA 2 InBr 5 containing both octahedral [InBr 6 3− ] and tetrahedral [InBr 4 − ] anions. Further increase of the MABr content leads to the formation of previously reported MA 4 InBr 7 , containing only octahedral [InBr 63− ] anions separated by Br − anions. Our results suggest that understanding the solution chemistry of multinary metal halide systems could be a valuable tool for discovering functional materials for practical applications.

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Section: Introductionmentioning

confidence: 99%

Investigation of the Solution Chemistry of Hybrid Organic–Inorganic Indium Halides for New Material Discovery

et al. 2022

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“…14,15 The missing piece of the puzzle is a systematic, first-principles analysis of the microscopic properties of tin halide solution complexes as building blocks for corresponding perovskite structures. Similar studies performed on lead halide counterparts have significantly contributed to disclosing the characteristics of these compounds [16][17][18][19][20][21] and, hence, to better understanding the evolution process of these systems from solution precursors to thin films through several intermediate steps. 22,23 In the case of Sn-based halide perovskites, such efforts have been conducted primarily in conjunction with experiments.…”

Section: Introductionmentioning

confidence: 76%

“…For these optimizations, we used the generalized gradient approximation in the Perdew-Burke-Ernzerhof (PBE) parameterization 30 together with the LANL2DZ basis set; pseudopotentials are adopted for Sn and I atoms, and the double-zeta basis set cc-pVDZ for the remaining lighter species. We checked that the choice of this functional, which is substantially more efficient than hybrid approximations and adopted in previous studies on similar systems, [16][17][18]20,21 does not affect the electronic structure of the resulting optimized structures. For single-point-geometry DFT calculations, for the population and natural bond order (NBO) analysis, as well as for the time-dependent DFT (TDDFT) runs, we adopt the range-separated hybrid functional CAM-B3LYP 31 in combination with the SDD basis set together with the corresponding SDD pseudopotentials for Sn and I, and the quadruple-zeta cc-pVQZ basis set for the lighter atoms.…”

Section: Methodsmentioning

confidence: 99%

“…In this study, we consider 14 tin iodide solution complexes characterized by a SnI 2 backbone in the axial configuration surrounded by four solvent molecules binding to it (see Figure 1). The initial geometries are set up based on earlier works on lead iodide solution complexes 6,17,20 while the choice of solvents is based on experimental work on tin halide perovskite precursors. 6 We consider the common solvents propylene carbonate (PC), which is a green compound, and DMSO as a point of reference for comparisons with Pb-based counterparts.…”

Section: Systemsmentioning

confidence: 99%

“…Earlier results obtained for equivalent PbI 2 M 4 systems indicate a similar trend, with the frontier states localized on the PbI 2 kernel with negligible or even vanishing contributions from the surrounding solvent molecules. 17,20 Further details on the orbital energies and spatial distributions of the inspected SnI 2 M 4 complexes can be found in the Supporting Information, Figures S1-S6. The absorption spectra of the SnI 2 M 4 complexes are reported in Figure 8, where the result obtained for the isolated SnI 2 molecule in an implicit DMSO solution is displayed for comparison on the bottom-right panel.…”

Section: Hmpamentioning

confidence: 99%

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Electronic Structure and Optical Properties of Tin Iodide Solution Complexes

Freerk¹,

Valencia²,

Cocchi³

2023

Preprint

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The emerging interest in tin-halide perovskites demands a robust understanding of the fundamental properties of these materials starting from the earliest steps of their synthesis. In a first-principles work based on time-dependent density-functional theory, we investigate the structural, energetic, electronic, and optical properties of 14 tin-iodide solution complexes formed by the SnI 2 unit tetracoordinated with molecules of common solvents, which we classify according to their Gutmann's donor number.We find that all considered complexes are energetically stable and their formation energy expectedly increases with the donating ability of the solvent. The energies of the frontier states are affected by the choice of the solvent with their absolute values decreasing with the donor number. The occupied orbitals are predominantly localized on the tin-iodide unit while the unoccupied ones are distributed also on the solvent molecules. Owing to this partial wave-function overlap, the first optical excitation is generally weak, although the spectral weight is red-shifted by the solvent molecules being coordinated to SnI 2 in comparison to the reference obtained for this molecule alone. Comparisons with results obtained on the same level of theory on Pb-based counterparts corroborate our analysis. The outcomes of this study provide quantummechanical insight into the fundamental properties of tin-iodide solution complexes. This knowledge is valuable in the research on lead-free halide perovskites and their precursors.

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First‐Principle Characterization of Structural, Electronic, and Optical Properties of Tin‐Halide Monomers

Schütt,

Valencia,

Cocchi

2024

ChemPhysChem

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The growing interest in tin‐halide semiconductors for photovoltaic applications demands an in‐depth knowledge of the fundamental properties of their constituents, starting from the smallest monomers entering the initial stages of formation. In this first‐principles work based on time‐dependent density‐functional theory, we investigate the structural, electronic, and optical properties of tin‐halide molecules SnXn2‐n, with n=1,2,3,4 and X = Cl, Br, I, simulating these compounds in vacuo as well as in an implicit solvent. We find that structural properties are very sensitive to the halogen species while the charge distribution is also affected by stoichiometry. The ionicity of the Sn‐X bond is confirmed by the Bader charge analysis albeit charge displacement plots point to more complex metal‐halide coordination. Particular focus is posed on the neutral molecules SnX2, for which electronic and optical properties are discussed in detail. Band gaps and absorption onset decrease with increasing size of the halogen species, and despite general common features, each molecule displays peculiar optical signatures. Our results are elaborated in the context of experimental and theoretical literature, including the more widely studied lead‐halide analogs, aiming to contribute with microscopic insight to a better understanding of tin‐halide perovskites.

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First-principles analysis of the optical properties of lead halide perovskite solution precursors

Abstract: Lead halide perovskites (LHPs) are promising materials for opto-electronics and photovoltaics, thanks to favorable characteristics and low manufacturing costs enabled by solution processing. In light of this, it is crucial...

Cited by 5 publications

References 61 publications

Investigation of the Solution Chemistry of Hybrid Organic–Inorganic Indium Halides for New Material Discovery

Investigation of the Solution Chemistry of Hybrid Organic–Inorganic Indium Halides for New Material Discovery

Electronic Structure and Optical Properties of Tin Iodide Solution Complexes

First‐Principle Characterization of Structural, Electronic, and Optical Properties of Tin‐Halide Monomers

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