Identifying and controlling phase purity in 2D hybrid perovskite thin films

Hu, Yinghong; Spies, Laura M.; Alonso-Álvarez, D.; Mocherla, Priyanka; Jones, Harry; Hanisch, Jonas; Bein, Thomas; Barnes, Piers R. F.; Docampo, Pablo

doi:10.1039/c8ta05475d

Cited by 64 publications

(85 citation statements)

References 39 publications

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“…The main features are located at 2.04 and 2.18 eV in all systems, which indicates a mixture of different n phases as discussed in ref. . We note that recently an empirical formula was established to estimate binding energies in perovskite quantum wells with varying perovskite layer sheets and binding energies ranging from 250 meV to 150 meV were found for the n = 2–4 systems .…”

Section: Photovoltaic Performance Parameters Including Standard Deviamentioning

confidence: 83%

The Role of Bulk and Interface Recombination in High‐Efficiency Low‐Dimensional Perovskite Solar Cells

et al. 2019

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Section: Photovoltaic Performance Parameters Including Standard Deviamentioning

confidence: 83%

The Role of Bulk and Interface Recombination in High‐Efficiency Low‐Dimensional Perovskite Solar Cells

et al. 2019

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“…It has been reported that solvent‐engineering with DMSO (relative polarity of 0.444 for DMSO vs 0.377 for DMAc) [ 31 ] can retard the crystallization rate. [ 32,33 ] The introduction of DMSO in the precursor solution results in a compact film morphology and significantly enhanced diffraction intensities at 14.1° (111) and 28.4° (202). To reveal the orientation of the RPP perovskite, grazing‐incidence wide‐angle X‐ray scattering (GIWAXS) analysis was conducted.…”

Section: Resultsmentioning

confidence: 99%

“…[ 43 ] Using a cosolvent with strong coordinating abilities for metal halides, the colloidal phase can be further solubilized by allowing facile intercalation of guest DMSO molecules into the organic spacer then decomposes into individual ions, including TEA + , MA + , and PbI 2 (DMSO) x complexes. Similar to the conventional stoichiometric recipe, [ 33,44 ] the nontemplate ions would partially convert into the more thermodynamically favorable low n ‐members phases and n = ∞ phase, rather than self‐assemble into the n = 3 perovskite. This theory is supported by the similar colloidal and film absorption spectra of the dissolved single‐crystal and stoichiometric‐mixture precursors (see Figure S13 in the Supporting Information).…”

Section: Resultsmentioning

confidence: 99%

Coordination Engineering of Single‐Crystal Precursor for Phase Control in Ruddlesden–Popper Perovskite Solar Cells

Qin

Zhong

Intemann

et al. 2020

Advanced Energy Materials

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efficiencies (PCE). [1,2] However, the intrinsic instability of 3D perovskite materials still remains unresolved. [3,4] Inert bulky organic cations can not only enhance their structural stability via strong interactions between covering organic cations and the [PbI 6 ] − units, but also block moisture from penetrating and corroding inner inorganic layers. [5,6] By incorporation of a larger cation into the 3D structure, the most common type is the (100)-oriented cutting direction, forming representative Ruddlesden-Popper perovskite (RPP) with a chemical formula (A′) 2 (A) n−1 Pb n I 3n+1 (A′ is a primary monovalent cations). [7,8] Unfortunately, the confinement effects of organic spacers also lead to a strong quantum and dielectric confinement in 2D perovskite. Moreover, the decreased conductivity of the organic layers prevents the carrier charge transport between perovskite quantum wells. [9] Thus, RPP exhibits a wider bandgap, a higher exciton binding energy (E b ), and lower charge mobility relative to the 3D perovskites, which results in poor efficiencies. Note that a weak quantum confinement would arise from an increase thickness of layers (n value), leading to a remarkable decrease in the optical bandgap, making it highly desirable to increase the number (n ≥ 4) of inorganic sheets between two adjacent organic spacers by forming quasi-2D structures. [10,11] In addition, through rational design 2D Ruddlesden-Popper perovskites (RPPs) have recently drawn significant attention because of their structural variability that can be used to tailor optoelectronic properties and improve the stability of derived photovoltaic devices. However, charge separation and transport in 2D perovskite solar cells (PSCs) suffer from quantum well barriers formed during the processing of perovskites. It is extremely difficult to manage phase distributions in 2D perovskites made from the stoichiometric mixtures of precursor solutions. Herein, a generally applicable guideline is demonstrated for precisely controlling phase purity and arrangement in RPP films. By visually presenting the critical colloidal formation of the single-crystal precursor solution, coordination engineering is conducted with a rationally selected cosolvent to tune the colloidal properties. In nonpolar cosolvent media, the derived colloidal template enables RPP crystals to preferentially grow along the vertically ordered alignment with a narrow phase variation around a target value, resulting in efficient charge transport and extraction. As a result, a recordhigh power conversion efficiency (PCE) of 14.68% is demonstrated for a (TEA) 2 (MA) 2 Pb 3 I 10 (n = 3) photovoltaic device with negligible hysteresis. Remarkably, superior stability is achieved with 93% retainment of the initial efficiency after 500 h of unencapsulated operation in ambient air conditions.

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“…However, luminescence intensity is also dependent on the native defects in the films, which are affected by the deposition conditions. Therefore, we performed comprehensive optimization of the film deposition conditions for (BA 0.5 PEA 0.5 ) 2 MAPb 2 Br 7 and BA 2 MAPb 2 Br 7 films, including the investigation of the factors that known to affect crystallization and/or optical quality, such as the effects of precursor purity, solvents and/or additives used, and the use of antisolvents . The details are given in Note S1 and Figures S6–S12 of the Supporting Information.…”

Section: Resultsmentioning

confidence: 99%

Mixed Spacer Cation Stabilization of Blue‐Emitting n = 2 Ruddlesden–Popper Organic–Inorganic Halide Perovskite Films

Leung

Tam

Liu

et al. 2019

Advanced Optical Materials

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Ruddlesden–Popper halide perovskite (RPP) materials are of significant interest for light‐emitting devices since their emission wavelength can be controlled by tuning the number of layers n, resulting in improved spectral stability compared to mixed halide devices. However, RPP films typically contain phases with different n, and the low n phases tend to be unstable upon exposure to humidity, irradiation, and/or elevated temperature which hinders the achievement of pure blue emission from n = 2 films. In this work, two spacer cations are used to form an RPP film with mixed cation bilayer and high n = 2 phase purity, improved stability, and brighter light emission compared to a single spacer cation RPP. The stabilization of n = 2 phase is attributed to favorable formation energy, reduced strain, and reduced electron–phonon coupling compared to the RPP films with only one type of spacer cation. Using this approach, pure blue light‐emitting diodes (LEDs) with Commission Internationale de l'éclairage (CIE) coordinates of (0.156, 0.088) and excellent spectral stability are achieved.

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Identifying and controlling phase purity in 2D hybrid perovskite thin films

Abstract: Improved phase purity in 2D hybrid perovskite thin films with horizontal crystal orientation was achieved through slow crystallization employing lead-complexing solvent additives.

Cited by 64 publications

References 39 publications

The Role of Bulk and Interface Recombination in High‐Efficiency Low‐Dimensional Perovskite Solar Cells

The Role of Bulk and Interface Recombination in High‐Efficiency Low‐Dimensional Perovskite Solar Cells

Coordination Engineering of Single‐Crystal Precursor for Phase Control in Ruddlesden–Popper Perovskite Solar Cells

Mixed Spacer Cation Stabilization of Blue‐Emitting n = 2 Ruddlesden–Popper Organic–Inorganic Halide Perovskite Films

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