Formation of Perovskite Heterostructures by Ion Exchange

Shewmon, Nathan T.; Yu, Hyeonggeun; Constantinou, Iordania; Klump, Erik; So, Franky

doi:10.1021/acsami.6b10034

Cited by 66 publications

(70 citation statements)

References 38 publications

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“…2C and D, both local PL lifetimes and surface potential show a close dependence on the concentration evolution, suggesting the correlated diffusion of vacancies during interdiffusion. These two measurements qualitatively indicate that the vacancy concentration is locally at equilibrium and depends only on the Br concentration.A constant interdiffusion coefficient D may be estimated by the average diffusion length L ≅ 2 ffiffiffiffiffi Dt p for an ideal semiinfinite model(27). The interdiffusion length is around 1∼2.5 μm after 1.5 h of constant heating, resulting in interdiffusion coefficient around 10 −13 ∼10 −12 cm 2 /s at 75-125°C.…”

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confidence: 99%

Intrinsic anion diffusivity in lead halide perovskites is facilitated by a soft lattice

Lai

Obliger

et al. 2018

Proc. Natl. Acad. Sci. U.S.A.

193

197

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Facile ionic transport in lead halide perovskites plays a critical role in device performance. Understanding the microscopic origins of high ionic conductivities has been complicated by indirect measurements and sample microstructural heterogeneities. Here, we report the direct visualization of halide anion interdiffusion in CsPbCl3–CsPbBr3 single crystalline perovskite nanowire heterojunctions using wide-field and confocal photoluminescence measurements. The combination of nanoscale imaging techniques with these single crystalline materials allows us to measure intrinsic anionic lattice diffusivities, free from complications of microscale inhomogeneity. Halide diffusivities were found to be between 10−13 and ∼10−12 cm2/second at about 100 °C, which are several orders of magnitudes lower than those reported in polycrystalline thin films. Spatially resolved photoluminescence lifetimes and surface potential measurements provide evidence of the central role of halide vacancies in facilitating ionic diffusion. Vacancy formation free energies computed from molecular simulation are small due to the easily deformable perovskite lattice, accounting for the high equilibrium vacancy concentration. Furthermore, molecular simulations suggest that ionic motion is facilitated by low-frequency lattice modes, resulting in low activation barriers for vacancy-mediated transport. This work elucidates the intrinsic solid-state ion diffusion mechanisms in this class of semisoft materials and offers guidelines for engineering materials with long-term stability in functional devices.

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mentioning

confidence: 99%

Intrinsic anion diffusivity in lead halide perovskites is facilitated by a soft lattice

Lai

Obliger

et al. 2018

Proc. Natl. Acad. Sci. U.S.A.

193

197

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“…This image suggests that this low-noisecurrent X-ray PIN photodiode could possibly realize better contrast in objects. In addition, ion exchange and migration [55][56][57][58] may degrade perovskite-based devices; here, the device is placed at temperatures from 15 (room temperature) to 90 °C in air to accelerate this phenomenon (Fig. 5a).…”

Section: Resultsmentioning

confidence: 99%

Low-noise X-ray PIN photodiodes made of perovskite single crystals by Solution-processed doped epitaxial growth

Wang¹,

Xu²,

Pan³

et al. 2020

Preprint

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X-ray photodiodes made of metal halide perovskites (MHPs) which directly convert X-ray photons into electron-hole pairs have shown advantages in low-cost and high X-ray detection sensitivity. However, devices fabricated by spin-coating and evaporation methods suffer from high traps density near poor interfacial layers (n-type/intrinsic and p-type/intrinsic) which lead to high dark current and noise current under large reverse bias. In this work, solution-processed doped epitaxial growth is employed to limit these traps through epitaxially growing n-type MHPs (bismuth-doped) and p-type MHPs (silver-doped) on opposite faces of intrinsic CH3NH3PbBr2.5Cl0.5 MHP single crystals. Through energy structure design, effective electron/hole blocking layers could decrease the noise and dark current, these X-ray PIN photodiodes work under a large external electrical field, which enables a state-of-art response speed (fall) of 750 ns and a lowest detectable dose rate of 17.7 nGys-1(40 kVp). This work will motivate new strategies to fabricate high-performance devices based on perovskites using solution-processed methods. These founding also explore a new generation of low dose and high dynamic X-ray detectors based on MHPs.

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“…Earlier attempts utilized ion‐exchange technique to create 3D/3D MAPbX 3 (X = Br, I) heterostructures, and realized self‐powered photodetectors; [ 9 ] since then the advance in structural design extended this material family to 2D/2D systems that exhibit enhanced heterojunction stability; however, at the cost of the device performance. [ 10 ] To make a trade‐off between the structural stability and device efficiency, notably, recent efforts have been devoted to fabricating 2D/3D hybrid perovskite heterostructures.…”

Section: Figurementioning

confidence: 99%

Solution‐Grown Large‐Sized Single‐Crystalline 2D/3D Perovskite Heterostructure for Self‐Powered Photodetection

Zhang

Liu

et al. 2020

Advanced Optical Materials

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that is simultaneously sensitive and costeffective. [1e,4] Today, a wide variety of photodetectors based on inorganic and organic semiconductor heterostructures are at our disposal. For example, MoS 2 / pyramid Si heterostructures have enabled the construction of photodiodes with ultrahigh detectivity in self-driven operation mode. [5] In rubrene-7,7,8,8tetracyanoquinodime heterostructures, the charge-transfer interface presents an external quantum efficiency of nearly 100%. [6] Compared with those inorganic and organic semiconductors, the recently emerged organic-inorganic hybrid perovskites provide several specific features to create heterostructures for novel photodetection devices. For instance, their excellent semiconductor properties, including large absorption coefficient, long carrier diffusion length, and high carrier mobility can give rise to efficient photocurrent generation. [7] Furthermore, their unique structural flexibility will enable a wide tunability in the bandgap and dimensionality, allowing for the creation of new heterostructures with exotic device properties. [8] Earlier attempts utilized ion-exchange technique to create 3D/3D MAPbX 3 (X = Br, I) heterostructures, and realized selfpowered photodetectors; [9] since then the advance in structural design extended this material family to 2D/2D systems that exhibit enhanced heterojunction stability; however, at the cost of the device performance. [10] To make a trade-off between the structural stability and device efficiency, notably, recent efforts have been devoted to fabricating 2D/3D hybrid perovskite heterostructures. [11] This integration can combine the hydrophobic properties of 2D perovskites with the superior charge-transport properties of their 3D counterparts, as has been demonstrated by their remarkable implementation in the optoelectronic field. [12] However, until now, those prepared 2D/3D perovskite heterostructures are typically polycrystalline or amorphous, in which the charge transport is usually plagued by unavoidable boundaryinduced defects and rich chemical disorders, limiting the optoelectronic performance of the resulting devices. [13] In contrast, a single-crystalline heterostructure with high crystalline purity and well-defined interface would overcome these obstacles and exhibit impressive improvements: lower intrinsic carrier concentration, higher carrier mobility, and longer carrier diffusion length. [14] Such characteristics make these materials an ideal medium for

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Formation of Perovskite Heterostructures by Ion Exchange

Cited by 66 publications

References 38 publications

Intrinsic anion diffusivity in lead halide perovskites is facilitated by a soft lattice

Intrinsic anion diffusivity in lead halide perovskites is facilitated by a soft lattice

Low-noise X-ray PIN photodiodes made of perovskite single crystals by Solution-processed doped epitaxial growth

Solution‐Grown Large‐Sized Single‐Crystalline 2D/3D Perovskite Heterostructure for Self‐Powered Photodetection

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