Ultrahigh sensitivity of methylammonium lead tribromide perovskite single crystals to environmental gases

Fang, Hong‐Hua; Adjokatse, Sampson; Wei, Haotong; Yang, Jie; Blake, Graeme R.; Huang, Jinsong; Even, Jacky; Loi, Maria Antonietta

doi:10.1126/sciadv.1600534

Cited by 338 publications

(448 citation statements)

References 47 publications

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“…2. (CH 3 NH 3 )PbBr 3 is extremely sensitive to gas adsorption [35,45], which can change surface band bending and trap state density, thus altering carrier diffusion and scattering. We point out the necessity to avoid exposure of OIPS to air and to prevent hydration of the surface prior to contacting, if energetic carriers are to be harvested in future experiments.…”

Section: Modeling Of Absorption and Emission Spectramentioning

confidence: 99%

“…Experimental data and their interpretation, however, show strong variations. Spectroscopic results obtained from thin films depend on growth technique [29][30][31][32][33], grain size [30,34], and environmental conditions [35,36].…”

Section: Introductionmentioning

confidence: 99%

“…Direct measurements of optical absorption spectra of single crystals in transmission are hindered by the short absorption length of visible light in OIPS [52], which forms a basis of their successful application in optoelectronics. Measurements in reflectance are surface-sensitive, and easily affected by hydration of the surface [35,45]. To create clean surfaces and avoid their subsequent hydration, we perform experiments on (CH 3 NH 3 )PbBr 3 single crystals cleaved in UHV.…”

Section: Introductionmentioning

confidence: 99%

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Temperature-dependent optical spectra of single-crystal (CH3NH3)PbBr3 cleaved in ultrahigh vacuum

et al. 2017

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We measure temperature-dependent one-photon and two-photon induced photoluminescence from (CH3NH3)PbBr3 single crystals cleaved in ultrahigh vacuum. An approach is presented to extract absorption spectra from a comparison of both measurements. Cleaved crystals exhibit broad photoluminescence spectra. We identify the direct optical band gap of 2.31 eV. Below 200 K the band gap increases with temperature, and it decreases at elevated temperature, as described by the BoseEinstein model. An excitonic transition is found 22 meV below the band gap at temperatures < 200 K. Defect emission occurs at photon energies < 2.16 eV. In addition, we observe a transition at 2.25 eV (2.22 eV) in the orthorhombic (tetragonal and cubic) phase. Below 200 K, the associated exciton binding energy is also 22 meV, and the transition redshifts at higher temperature. The binding energy of the exciton related to the direct band gap, in contrast, decreases in the cubic phase. High-energy emission from free carriers is observed with higher intensity than reported in earlier studies. It disappears after exposing the crystals to air.

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Section: Modeling Of Absorption and Emission Spectramentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Temperature-dependent optical spectra of single-crystal (CH3NH3)PbBr3 cleaved in ultrahigh vacuum

et al. 2017

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“…41 Similarly, Fang and coworkers showed a PL variation of MAPbBr 3 single crystals (MSCs) by exposing them to different gases. 42 These works made a great contribution for the understanding of perovskites' properties; however, the primary mechanism for the PL change under different atmospheres or pressures has not been rigorously proved. As one possibility, Fang et al explained that positive charges at the crystal surface, which can be neutralized by the physisorption of O 2 and H 2 O, are responsible for weak PL in vacuum, 42 while there is another possibility that shallow trap states, which are induced by air infiltration or surface degradation, contribute to high PL intensity in air.…”

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confidence: 99%

Reversible air-induced optical and electrical modulation of methylammonium lead bromide (MAPbBr3) single crystals

Zhang

Liu

et al. 2017

Applied Physics Letters

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The photoluminescence (PL) variations of organic-inorganic hybrid lead halide perovskites in different atmospheres are well documented, while the fundamental mechanism still lacks comprehensive understandings. This study reports the reversible optical and electrical properties of methylammonium lead bromide (MAPbBr3 or CH3NH3PbBr3) single crystals caused by air infiltration. With the change in the surrounding atmosphere from air to vacuum, the PL intensity of perovskite single crystals decreases, while the conductivity increases. By means of first-principles computational studies, the shallow trap states are considered as key elements in PL and conductivity changes. These results have important implications for the characterization and application of organic-inorganic hybrid lead halide perovskites in vacuum.

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“…24,25 Galisteo-López et al found that moisture can cause strong photodarkening of MAPbI3 film, while oxygen will induce photoactivation of the PL emission. 24 Fang et al reported oxygen and water molecules cause PL enhancement of MAPbBr3 single crystals.…”

mentioning

confidence: 99%

Inhomogeneous degradation in metal halide perovskites

Yang

Zhang

Cao

et al. 2017

Applied Physics Letters

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Although the rapid development of organic-inorganic metal halide perovskite solar cells has led to certified power conversion efficiencies of above 20%, their poor stability remains a major challenge, preventing their practical commercialization. In this paper, we investigate the intrinsic origin of the poor stability in perovskite solar cells by using a confocal fluorescence microscope. We find that the degradation of perovskite films starts from grain boundaries and gradually extend to the center of the grains. Firmly based on our findings, we further demonstrate that the device stability can be significantly enhanced by increasing the grain size of perovskite crystals. Our results have important implications to further enhance the stability of optoelectronic devices based on metal halide perovskites.

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Ultrahigh sensitivity of methylammonium lead tribromide perovskite single crystals to environmental gases

Abstract: Extremely low surface trap densities and ultrahigh sensitivity to oxygen and water molecules are demonstrated in perovskite single crystals.

Cited by 338 publications

References 47 publications

Temperature-dependent optical spectra of single-crystal (CH3NH3)PbBr3 cleaved in ultrahigh vacuum

Temperature-dependent optical spectra of single-crystal (CH3NH3)PbBr3 cleaved in ultrahigh vacuum

Reversible air-induced optical and electrical modulation of methylammonium lead bromide (MAPbBr3) single crystals

Inhomogeneous degradation in metal halide perovskites

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