Spatial Charge Separation as the Origin of Anomalous Stark Effect in Fluorous 2D Hybrid Perovskites

Queloz, Valentin I. E.; Bouduban, Marine E. F.; García‐Benito, Inés; Fedorovskiy, Alexander E.; Orlandi, Simonetta; Cavazzini, Marco; Pozzi, Gianluca; Trivedi, Harsh; Beljonne, David; Moser, Jacques‐E.; Nazeeruddin, Mohammad Khaja; Quarti, Claudio; Grancini, Giulia

doi:10.1002/adfm.202000228

Cited by 13 publications

(19 citation statements)

References 48 publications

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“…It is the combination of structure effect and electrostatic effect that promotes the formation of confined hole states in the valence band edge space, stabilizes the electron-hole pairs with loose interaction, reduces recombination, and prolongs the lifetime. [48] As reported in the literature, V OC losses are caused by radiation recombination and nonradiation recombination involving traps or energy misalignment. Since the change of bandgap is negligible in the SUG-2D perovskite film, the little higher V OC of the SUG-2D-based device is mainly due to the reduction of nonradiative recombination loss in the film.…”

Section: Resultsmentioning

confidence: 91%

Spontaneous Formation of Upper Gradient 2D Structure for Efficient and Stable Quasi‐2D Perovskites

Xing

Huang

et al. 2021

Advanced Materials

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Highly efficient and stable quasi-2D hybrid perovskite solar cells (PSCs) using hydrophobic 4-(trifluoromethyl) benzylamine (4TFBZA) as the spacer cation are successfully demonstrated. It is found that the incorporation of hydrophobic 4TFBZA into MAPbI 3 can effectively induce a spontaneous upper gradient 2D (SUG-2D) structure, passivate the trap states, and restrain the ion motion. Meanwhile, the strong hydrogen bonding of F•••HN between 4TFBZA ions and methylamine ions can effectively suppress the decomposition of perovskite, which gives the device a better thermal stability. Besides, due to the SUG-2D structure with hydrophobic 4TFBZA, the device also exhibits a better moisture stability. The SUG-2D-structure-based device exhibits a power conversion efficiency of 17.07% with a high open-circuit voltage of 1.10 V and a notable fill factor of 71%. This work provides a new strategy for constructing efficient and stable quasi-2D PSCs, and it is an inspiration for the packaging strategy of perovskites.

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Section: Resultsmentioning

confidence: 91%

Spontaneous Formation of Upper Gradient 2D Structure for Efficient and Stable Quasi‐2D Perovskites

Xing

Huang

et al. 2021

Advanced Materials

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“…The shape of the signal in both the PDMA-I and PDEA-I spectra appears to closely match that of the second derivative of the absorption spectra, shown by the dashed black line, which allows us to conclude that the positive features arise due to a photoinduced Stark effect. Stark effects, first evidenced in hybrid perovskite materials in 2014, and subsequently in 2D-perovskites , and perovskite nanocrystals, arise due to a change in the absorption of a material in the presence of an electric field; in the case of the photoinduced Stark effect, the electric field is a photoinduced (local) field. The photoinduced signal, Δ A , has been shown to comprise a linear combination of the first and second derivatives of the absorption spectrum .…”

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confidence: 99%

The Role of Alkyl Chain Length and Halide Counter Ion in Layered Dion−Jacobson Perovskites with Aromatic Spacers

Dučinskas

Hope

Merten

et al. 2021

J. Phys. Chem. Lett.

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Layered hybrid perovskites based on Dion–Jacobson phases are of interest to various optoelectronic applications. However, the understanding of their structure–property relationships remains limited. Here, we present a systematic study of Dion–Jacobson perovskites based on (S)PbX4 (n = 1) compositions incorporating phenylene-derived aromatic spacers (S) with different anchoring alkylammonium groups and halides (X = I, Br). We focus our study on 1,4-phenylenediammonium (PDA), 1,4-phenylenedimethylammonium (PDMA), and 1,4-phenylenediethylammonium (PDEA) spacers. Systems based on PDA did not form a well-defined layered structure, showing the formation of a 1D structure instead, whereas the extension of the alkyl chains to PDMA and PDEA rendered them compatible with the formation of a layered structure, as shown by X-ray diffraction and solid-state NMR spectroscopy. In addition, the control of the spacer length affects optical properties and environmental stability, which is enhanced for longer alkyl chains and bromide compositions. This provides insights into their design for optoelectronic applications.

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“…In addition, mixing MAPbI 3 with t ‐BA‐based 2DHPs has been reported to help mitigate moisture instability [44] . A band gap opening accompanied by octahedral distortion away from cubic symmetry was observed in BA‐based 2D systems upon fluorination of the spacers, [45] as well as in Pb−Sn 2DHP systems [46] . Charge transport properties of 2D halide perovskites have been characterized by time‐resolved microwave conductivity (TRMC) measurements, [30,47] and modeled by calculating the effective masses through the band transport model [28,30] .…”

Section: Introductionmentioning

confidence: 99%

Organic Spacers in 2D Perovskites: General Trends and Structure‐Property Relationships from Computational Studies

Jahanbakhshi

Mladenović

Dankl

et al. 2021

Helvetica Chimica Acta

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Addition of large organic molecules to halide perovskites has been shown to provoke dimensionality reduction and formation of two‐dimensional phases that demonstrate improved long‐term stabilities. Optoelectronic properties of the resulting 2D layered perovskites are strongly influenced by the chemical nature of the additive molecules, which opens immense possibilities for preparation of materials with tailored properties. However, given the huge chemical space of possible organic spacers, a systematic and exhaustive search for optimal compounds is impossible and general structure–property relationships that could guide a rational design are still largely absent. Here, we provide an overview of a series of recent computational studies from our group on different types of spacers. We first develop a simplified universal monovalent cation model to map out approximate structural stability maps as a function of the van der Waals radius and the magnitude of dispersion interactions to monitor the possible emergence of 2D phases. We further provide structural and photophysical insights from classical and first‐principles molecular dynamics simulations and density functional theory calculations on 2D hybrid perovskites based on a wide range of spacers with different chemical nature and varying conformational properties. Our computational predictions are validated through comparison with powder diffraction, conductivity and optical measurements. Such comparative study allows for providing some general structure–property correlations, which can serve as design guidelines in the search for optimal 2D and mixed 2D/3D perovskite photovoltaic materials.

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Spatial Charge Separation as the Origin of Anomalous Stark Effect in Fluorous 2D Hybrid Perovskites

Cited by 13 publications

References 48 publications

Spontaneous Formation of Upper Gradient 2D Structure for Efficient and Stable Quasi‐2D Perovskites

Spontaneous Formation of Upper Gradient 2D Structure for Efficient and Stable Quasi‐2D Perovskites

The Role of Alkyl Chain Length and Halide Counter Ion in Layered Dion−Jacobson Perovskites with Aromatic Spacers

Organic Spacers in 2D Perovskites: General Trends and Structure‐Property Relationships from Computational Studies

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