Tracking Structural Phase Transitions in Lead‐Halide Perovskites by Means of Thermal Expansion

Keshavarz, Masoumeh; Ottesen, Martin; Wiedmann, Steffen; Wharmby, Michael T.; Küchler, R.; Yuan, Haifeng; Debroye, Elke; Steele, Julian A.; Martens, Johan A.; Hussey, N. E.; Bremholm, Martin; Roeffaers, Maarten B. J.; Hofkens, Johan

doi:10.1002/adma.201900521

Cited by 109 publications

(137 citation statements)

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“…[ 10 ] Δ L / L is positive with the same magnitude for all compounds, yet, above the phase transition temperature T p , Δ L / L ∝ T in contrast to the methylammonium‐based lead halide materials. [ 51 ] Both Δ L / L and α are illustrated for the temperature region in the vicinity of the structural phase transition temperature in Figure 4d. The T p s are summarized in Figure 4g for all materials extracted from the maximum of α.…”

Section: Cs2agbibr6 (Cs098rb002)2agbibr6 (Cs098k002)2agbibr6 (Cs0mentioning

confidence: 99%

Tuning the Structural and Optoelectronic Properties of Cs₂AgBiBr₆ Double‐Perovskite Single Crystals through Alkali‐Metal Substitution

et al. 2020

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The discovery of lead-based organicinorganic perovskite materials for optoelectronic applications has triggered a revolution in photovoltaic material research. Despite their exceptional material properties such as strong light absorption, long charge carrier lifetimes in combination with high carrier mobility, and low production costs, their long-term instability, and the toxicity of lead currently hamper their deployment at an industrial scale. [1] To overcome this drawback, double perovskites with the general formula A 2 1+ M 1+ M′ 3+ X 6 have been proposed as candidate materials providing leadfree alternatives in the vastly expanding research field of perovskites. One of the first materials investigated in this branch of the perovskite catalog is Cs 2 AgBiBr 6 , demonstrating high stability in devices [2,3] and low effective carrier masses [4] with the long carrier recombination lifetimes Lead-free double perovskites have great potential as stable and nontoxic optoelectronic materials. Recently, Cs 2 AgBiBr 6 has emerged as a promising material, with suboptimal photon-to-charge carrier conversion efficiency, yet well suited for high-energy photon-detection applications. Here, the optoelectronic and structural properties of pure Cs 2 AgBiBr 6 and alkalimetal-substituted (Cs 1−x Y x) 2 AgBiBr 6 (Y: Rb + , K + , Na + ; x = 0.02) single crystals are investigated. Strikingly, alkali-substitution entails a tunability to the material system in its response to X-rays and structural properties that is most strongly revealed in Rb-substituted compounds whose X-ray sensitivity outperforms other double-perovskite-based devices reported. While the fundamental nature and magnitude of the bandgap remains unchanged, the alkali-substituted materials exhibit a threefold boost in their fundamental carrier recombination lifetime at room temperature. Moreover, an enhanced electron-acoustic phonon scattering is found compared to Cs 2 AgBiBr 6. The study thus paves the way for employing cation substitution to tune the properties of double perovskites toward a new material platform for optoelectronics.

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Section: Cs2agbibr6 (Cs098rb002)2agbibr6 (Cs098k002)2agbibr6 (Cs0mentioning

confidence: 99%

Tuning the Structural and Optoelectronic Properties of Cs₂AgBiBr₆ Double‐Perovskite Single Crystals through Alkali‐Metal Substitution

et al. 2020

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“…[1][2][3][4][5] Perovskites with ABX 3 structure are typically composed of organic cations at A site and inorganic cages BX 6 (B = Pb 2+ , Sn 2+ ; X = I − , Br − , Cl − ). [6,7] Owing to the small rotational energy and nonspherical nature, the organic cations with intrinsic dipole moment induce a dipolar polarization. [8,9] And the presence of the heavy elements (Pb 2+ and I − ) in APbI 3 leads to significant spin-orbit coupling (SOC), thus excitons in hybrid perovskites possess both orbital (L) and spin (S) momentums with the total momentum J = L + S. [10][11][12] In general, the electrical polarization plays an important role in suppressing the charge recombination, facilitating charge transport, and even polarizing excited states, which are critically MA/FA ratio in the MA x FA (1−x) PbI 3 .…”

Section: Introductionmentioning

confidence: 99%

Identifying Photoinduced Dipolar Polarization and Orbit–Orbit Interaction between Excitons in Organic–Inorganic Hybrid Perovskites

Dou

Wang

Zhang

et al. 2020

Adv Funct Materials

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Photoinduced polarization and orbit-orbit interaction are important issues in hybrid perovskites toward developing optoelectronic functionalities. This paper identifies that photoinduced polarization occurs in hybrid perovskites with mixed-cation methylammonium (MA)/formamidinium (FA) (MA x FA (1−x) PbI 3) by measuring bulk polarization at 1 MHz in a magnetic field. Interestingly, when the internal dipole moment is increased upon increasing the MA:FA ratio, the photoinduced dipolar polarization can be substantially enhanced, clarifying the controversial issue of whether photoexcitation can induce a dielectric polarization within dipolar polarization regime in hybrid perovskites. Furthermore, upon increasing photoinduced dipolar polarization, it is found that the intrinsic orbit-orbit interaction between excitons can be increased, revealed by monitoring photocurrent change (ΔJ sc) upon switching the photoexcitation between linear and circular polarizations. This presents that organic cations are directly involved in the orbit-orbit interaction within band structures. Clearly, the studies provide an insightful understanding of the dipole moment effects on photoinduced dipolar polarization and orbit-orbit interaction between excitons in hybrid perovskites toward controlling the optoelectronic properties.

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“…We note that the δ-FAPbBr 3 phase is not observed at high RH ( Supplementary Fig. 14) because δ-FAPbBr 3 is only stable below −8°C (265 K) 54 .…”

Section: Synthesis Of Layered Formamidinium Metal Halide Perovskitesmentioning

confidence: 93%

Reversible multicolor chromism in layered formamidinium metal halide perovskites

et al. 2020

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Metal halide perovskites feature crystalline-like electronic band structures and liquid-like physical properties. The crystal–liquid duality enables optoelectronic devices with unprecedented performance and a unique opportunity to chemically manipulate the structure with low energy input. In this work, we leverage the low formation energy of metal halide perovskites to demonstrate multicolor reversible chromism. We synthesized layered Ruddlesden-Popper FAn+1PbnX3n+1 (FA = formamidinium, X = I, Br; n = number of layers = 1, 2, 3 … ∞) and reversibly tune the dimensionality (n) by modulating the strength and number of H-bonds in the system. H-bonding was controlled by exposure to solvent vapor (solvatochromism) or temperature change (thermochromism), which shuttles FAX salt pairs between the FAn+1PbnX3n+1 domains and adjacent FAX “reservoir” domains. Unlike traditional chromic materials that only offer a single-color transition, FAn+1PbnX3n+1 films reversibly switch between multiple colors including yellow, orange, red, brown, and white/colorless. Each colored phase exhibits distinct optoelectronic properties characteristic of 2D superlattice materials with tunable quantum well thickness.

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Tracking Structural Phase Transitions in Lead‐Halide Perovskites by Means of Thermal Expansion

Abstract: The success of hybrid organic-inorganic perovskites (HOIP) in photovoltaic applications is based on their high power conversion efficiencies, up to 23.3%, in combination with seemingly

Cited by 109 publications

References 43 publications

Tuning the Structural and Optoelectronic Properties of Cs₂AgBiBr₆ Double‐Perovskite Single Crystals through Alkali‐Metal Substitution

Tuning the Structural and Optoelectronic Properties of Cs₂AgBiBr₆ Double‐Perovskite Single Crystals through Alkali‐Metal Substitution

Identifying Photoinduced Dipolar Polarization and Orbit–Orbit Interaction between Excitons in Organic–Inorganic Hybrid Perovskites

Reversible multicolor chromism in layered formamidinium metal halide perovskites

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Tracking Structural Phase Transitions in Lead‐Halide Perovskites by Means of Thermal Expansion

Abstract: The success of hybrid organic-inorganic perovskites (HOIP) in photovoltaic applications is based on their high power conversion efficiencies, up to 23.3%, in combination with seemingly

Cited by 109 publications

References 43 publications

Tuning the Structural and Optoelectronic Properties of Cs2AgBiBr6 Double‐Perovskite Single Crystals through Alkali‐Metal Substitution

Tuning the Structural and Optoelectronic Properties of Cs2AgBiBr6 Double‐Perovskite Single Crystals through Alkali‐Metal Substitution

Identifying Photoinduced Dipolar Polarization and Orbit–Orbit Interaction between Excitons in Organic–Inorganic Hybrid Perovskites

Reversible multicolor chromism in layered formamidinium metal halide perovskites

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Tuning the Structural and Optoelectronic Properties of Cs₂AgBiBr₆ Double‐Perovskite Single Crystals through Alkali‐Metal Substitution

Tuning the Structural and Optoelectronic Properties of Cs₂AgBiBr₆ Double‐Perovskite Single Crystals through Alkali‐Metal Substitution