Defect step controlled growth of perovskite MAPbBr3 single crystal

Shen, Hongxia; Nan, Ruihua; Jian, Zengyun; Li, Xiaojuan

doi:10.1007/s10853-019-03710-6

Cited by 47 publications

(28 citation statements)

References 31 publications

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“…Although the high-resolution X-ray diffraction (HR-XRD) reveals its single crystalline nature in the bulk (Figure S1, Supporting Information), the surface is covered with multiple of pits and micro-crystallites, resulting from spontaneous nucleation. [31][32][33] This surface roughness is also confirmed by the atomic force microscopy (AFM) topographic image (Figure 1d). X-ray photoelectron spectroscopy (XPS) analysis reveals that the surface chemical composition significantly deviates from the ideal stoichiometry (Figure 1g).…”

Section: Resultssupporting

confidence: 59%

Observation of 3D Biexcitons in Pristine‐Quality CH₃NH₃PbBr₃ Single Crystals

et al. 2022

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Regarding the latter, for example, the basic issue such as "the identity of optical excitation at room temperature" is still controversial, because there are contradicting evidences for two candidates, free carriers and excitons. [9,10] The key question is the stability of the exciton against thermal ionization of the constituents. The exciton binding energy ϕ X in 3D HPs such as MAPbX 3 (MA = CH 3 NH 3 , X = I, Br, Cl) ranges from 15 meV to 70 meV, [9,11,12] which is indeed comparable to room temperature (≈26 meV), and therefore, an exciton may or may not be stable. However, optical excitation is certainly excitonic at low temperatures, for example, 10 K (≈0.9 meV).Like a hydrogen molecule formed by binding of two hydrogen atoms, two excitons can bind to form an excitonic molecule, typically known as a biexciton. The numerical value for the biexciton binding energy ϕ XX can be roughly estimated by a theoretical model, which predicts its universal dependence on ϕ X and the effective mass ratio σ between the electron and the hole. [13][14][15] According to variational methods, [16,17] the predicted ϕ XX for MAPbBr 3 (ϕ X = 38 meV [9] and σ ≈ 1 [18] ) can range from 1.0 meV to 4.8 meV, which is sufficiently large to ensure the stability of the biexciton at nominal cryogenic temperatures. However, there is no single experimental evidence for their existence in the 3D HPs, which is quite surprising because biexcitons are well established in conventional semiconductors like Si and Ge with similar and even much smaller values of ϕ XX = 1.5 meV [19] and 0.3 meV, [20] respectively.Here, we demonstrate that biexcitons do exist in 3D MAPbBr 3 single crystals at low temperatures (T < 30 K). However, biexcitons are unstable at the crystal exposed to ambient, explaining their elusive nature when probing as-grown crystals with typical photoluminescence (PL) spectroscopy. Therefore, the freshcut pristine quality of the crystal should be established for the stable biexciton formation. The evidence of the biexcitonic phase is very clear from the rapidly growing PL peak having an inverted Boltzmann shape, reflecting the kinetic energy distribution of the biexcitons. [21,22] We show that a cold biexciton can be directly generated using giant resonant two-photon absorption (2PA) with polarization control aided by the nanoscale surface flatness of the crystal with fine-scale photoluminescence Halide perovskites (HPs) are fascinating materials whose optoelectronic properties are arguably excitonic. In the HP family, biexcitons are known to exist only in low dimensions where exciton-exciton binding is strongly enhanced by quantum and dielectric confinements. In this paper, however, it is shown that they indeed do exist in 3D bulk CH 3 NH 3 PbBr 3 (MAPbBr 3 ) single crystals if the pristine crystal quality is ensured for subtle binding of two excitons. The existence of biexcitons is clearly evidenced below 30 K with a binding energy of ≈3.9 ± 0.3 meV according to i) exciton-biexciton population dynamics, ii) giant resonant two-photon ex...

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Section: Resultssupporting

confidence: 59%

Observation of 3D Biexcitons in Pristine‐Quality CH₃NH₃PbBr₃ Single Crystals

et al. 2022

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“…The crystal structures of the MAPbBr 3 –MAAc and MAPbBr 3 –DMF:DMSO films were characterized by X‐ray diffraction (XRD) in Figure 1e. The diffraction peaks located at 15.2°, 30.08°, and 45.79° are observed from both MAPbBr 3 –MAAc and MAPbBr 3 –DMF:DMSO films, assigned to the (100), (200), and (300) planes of MAPbBr 3 perovskite cubic phase, [ 41–44 ] respectively. But the (100) and (200) peaks of MAPbBr 3 –MAAc are notably stronger and sharper than those of MAPbBr 3 –DMF:DMSO, indicating a high crystalline quality of the MAPbBr 3 –MAAc perovskite film fabrication.…”

Section: Resultsmentioning

confidence: 99%

“…The crystal structures of the MAPbBr 3 -MAAc and MAPbBr 3 -DMF:DMSO films were characterized by X-ray diffraction (XRD) in Figure 1e. The diffraction peaks located at 15.2°, 30.08°, and 45.79° are observed from both MAPbBr 3 -MAAc and MAPbBr 3 -DMF:DMSO films, assigned to the (100), (200), and (300) planes of MAPbBr 3 perovskite cubic phase, [41][42][43][44] respectively. But the (100) and ( 200 It is well known that Raman microprobe applied on materials or devices is a good technique to detect the local variations and changes of the crystal structure.…”

Section: Structures and Morphologies Of The Mapbbr 3 -Maac And Mapbbr 3 -Dmf:dmso Filmsmentioning

confidence: 99%

Air‐Processed MAPbBr₃ Perovskite Thin Film with Ultrastability and Enhanced Amplified Spontaneous Emission

Luo

Liu

et al. 2021

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The poor stability, in particular with respect to temperature, moisture, and light exposure, remains a ubiquitous impediment virtually for metal halide perovskite materials and devices in their future practical application. Herein, from the perspective of precursor solution chemistry, ionic liquid solvent methylammonium acetate (MAAc) is introduced to prepare high‐quality MAPbBr3 perovskite thin films in a one‐step air‐processing process without anti‐solvent treatment. Due to formation of pinhole‐free, uniform, and compact MAPbBr3 perovskite film, excellent amplified spontaneous emission (ASE) with high emission efficiency and low threshold is obtained under nanosecond laser. Furthermore, the prepared MAPbBr3 perovskite exhibits excellent two‐photon induced ASE with a low threshold of 100 µJ cm−2 under 800 nm femtosecond laser excitation. More importantly, in comparison with the traditional MAPbBr3 films prepared with N,N‐dimethylformamide (DMF) and dimethyl sulfoxide (DMSO), the MAPbBr3 film prepared with MAAc shows excellent optical stability: no signs of degradation under more than 2 h pulsed laser excitation, stable ASE emission spectra under the humidity of 95% and ASE spectra can be stimulated when films are kept in air for more than 6000 h without encapsulation.

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“…It was found that the roughness and crystallinity of the lm were signi cantly improved by using anisole as the antisolvent, the PCE of perovskite solar cells prepared with anisole as antisolvent reached 19.42%. [21,22] Based on the above research, our group proposed to apply environmentally friendly solvent to regulate the process of perovskite crystallization in order to achieve high-quality perovskite lms. We studied the effects of green organic solvents (such as propyl acetate and propylene glycol methyl ether) on the morphology and performance of perovskite solar cells.…”

Section: Introductionmentioning

confidence: 99%

Environment-friendly High Efficiency CH3NH3PbI3 Perovskite Solar Cells Fabricated by Green Antisolvent Method

Gao

Meng

2021

Preprint

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Green antisolvents propyl acetate and isooctane can promote the nucleation of PbI2 particles and provide the heterogeneous nucleation site of perovskite crystal, so as to promote the rapid growth of perovskite crystal. The films treated with propyl acetate and propylene glycol methyl ether have larger grains and lower root-mean-square value (RMS) than those treated with chlorobenzene. The full coverage perovskite films with uniform grain size which is closer to the exciton diffusion length of perovskite can be obtained. Compared with the CH3NH3PbI3 perovskite solar cells treated with chlorobenzene (power conversion efficiency (PCE) is 17.86%), the best efficiency of the devices treated with propylene glycol methyl ether is 21.60%, which is improved by 21%, which has certain reference value and guiding significance for researchers to obtain environment-friendly high-quality perovskite solar cells in the future.

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Defect step controlled growth of perovskite MAPbBr3 single crystal

Cited by 47 publications

References 31 publications

Observation of 3D Biexcitons in Pristine‐Quality CH₃NH₃PbBr₃ Single Crystals

Observation of 3D Biexcitons in Pristine‐Quality CH₃NH₃PbBr₃ Single Crystals

Air‐Processed MAPbBr₃ Perovskite Thin Film with Ultrastability and Enhanced Amplified Spontaneous Emission

Environment-friendly High Efficiency CH3NH3PbI3 Perovskite Solar Cells Fabricated by Green Antisolvent Method

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Defect step controlled growth of perovskite MAPbBr3 single crystal

Cited by 47 publications

References 31 publications

Observation of 3D Biexcitons in Pristine‐Quality CH3NH3PbBr3 Single Crystals

Observation of 3D Biexcitons in Pristine‐Quality CH3NH3PbBr3 Single Crystals

Air‐Processed MAPbBr3 Perovskite Thin Film with Ultrastability and Enhanced Amplified Spontaneous Emission

Environment-friendly High Efficiency CH3NH3PbI3 Perovskite Solar Cells Fabricated by Green Antisolvent Method

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Observation of 3D Biexcitons in Pristine‐Quality CH₃NH₃PbBr₃ Single Crystals

Observation of 3D Biexcitons in Pristine‐Quality CH₃NH₃PbBr₃ Single Crystals

Air‐Processed MAPbBr₃ Perovskite Thin Film with Ultrastability and Enhanced Amplified Spontaneous Emission