O<sub>2</sub> as a molecular probe for nonradiative surface defects in CsPbBr<sub>3</sub> perovskite nanostructures and single crystals

Rodà, Carmelita; Abdelhady, Ahmed L.; Shamsi, Javad; Lorenzon, Monica; Pinchetti, Valerio; Gandini, Marina; Meinardi, Francesco; Manna, Liberato; Brovelli, Sergio

doi:10.1039/c9nr01133a

Cited by 41 publications

(39 citation statements)

References 74 publications

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“…Despite this, the effects of the environment on the optical properties of lead halide perovskites NCs have been surprisingly poorly investigated to date, with only few experiments on CsPbBr 3 nanocubes grown by hot-injection method, curiously finding contradictory results. In particular, the PL intensity in air has been reported to be lower than in vacuum [3,28], or not affected by the environment [27]. These results are different from the ones on single crystals, bulk polycrystalline thin films, and even nanosheets and nanowires [3], all showing a PL intensity enhancement in air.…”

Section: Introductionmentioning

confidence: 82%

“…In particular, the PL intensity in air has been reported to be lower than in vacuum [3,28], or not affected by the environment [27]. These results are different from the ones on single crystals, bulk polycrystalline thin films, and even nanosheets and nanowires [3], all showing a PL intensity enhancement in air.…”

Section: Introductionmentioning

confidence: 82%

“…In particular, perovskite nanocrystals (NCs) are very interesting due to the possibility to engineer the optical properties by acting on the chemical composition [1], the size, the shape [2,3], and even the crystalline packing dimensionality within each NC [4]. Moreover, efficient NCs electroluminescence [5] and low threshold amplified spontaneous emission [6][7][8][9] have been demonstrated, thus proposing them as possible active materials in LEDs and lasers.…”

Section: Introductionmentioning

confidence: 99%

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Investigation of the Role of the Environment on the Photoluminescence and the Exciton Relaxation of CsPbBr3 Nanocrystals Thin Films

et al. 2020

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In this work, we present a detailed optical investigation of the effects of the environment on the photoluminescence (PL) spectra and the relaxation dynamics of pristine and aged CsPbBr3 nanocrystal (NC) thin films. We demonstrate that, contrary to previous results on similar NCs, the PL intensity of pristine NCs is higher when the sample is in wet air than in vacuum, due to the passivation of defects reducing the free exciton trapping and the bound excitons non-radiative relaxation. The aged NCs show a PL intensity increase in wet air nine times stronger than the pristine ones, due to an interplay between static and dynamic effects, increasing the number of emitting NCs and reducing the non-radiative recombination rate of free excitons. These results improve the understanding of the possible interactions between perovskite NCs and the environment, which could be relevant for the development of optical gas sensors exploiting perovskite NCs.

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Section: Introductionmentioning

confidence: 82%

Section: Introductionmentioning

confidence: 82%

Section: Introductionmentioning

confidence: 99%

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Investigation of the Role of the Environment on the Photoluminescence and the Exciton Relaxation of CsPbBr3 Nanocrystals Thin Films

et al. 2020

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“…O 2 was then used as a molecular probe to compare and contrast the ability of the proposed ALD modes to grow gas diffusion barriers. Recent reports have demonstrated reduction in the PL of CsPbBr 3 NCs in the presence of molecular O 2 . The authors have suggested that this behavior is due to the interaction of O 2 with the NC surface.…”

Section: Resultsmentioning

confidence: 99%

“…Herein, we optimize the above‐mentioned ALD protection scheme for CsPbBr 3 NC films by using O 2 as a molecular diffusion probe to assess the uniformity of the encapsulating AlO x layer. The O 2 quenches the PL by extracting photogenerated charges . The better the gas barrier properties of ALD layer are, the less quenching is expected when the CsPbBr 3 /AlO x nanocomposites are exposed to an O 2 ‐rich atmosphere .…”

Section: Introductionmentioning

confidence: 99%

Optimizing the Atomic Layer Deposition of Alumina on Perovskite Nanocrystal Films by Using O₂ As a Molecular Probe

Saris

Dona

Niemann

et al. 2020

Helvetica Chimica Acta

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Encapsulation methods have shown to be effective in imparting improved stability to metal‐halide perovskite nanocrystals (NCs). Atomic layer deposition (ALD) of metal oxides is one of the promising approaches for such encapsulation, yet better control on the process parameters are required to achieve viable lifetimes for several optoelectronic and photocatalytic applications. Herein, we optimize the ALD process of amorphous aluminum oxide (AlOx) as an encapsulating layer for CsPbBr3 NC thin films by using oxygen (O2) as a molecular diffusion probe to assess the uniformity of the deposited AlOx layer. When O2 reaches the NC surface, it extracts the photogenerated electrons, thus quenching the PL of the CsPbBr3 NCs. As the quality of the ALD layer improves, less quenching is expected. We compare three different ALD deposition modes. We find that the low temperature/high temperature and the exposure modes improve the quality of the alumina as a gas barrier when compared with the low temperature mode. We attribute this result to a better diffusion of the ALD precursor throughout the NC film. We propose the low temperature/high temperature as the most suitable mode for future implementation of multilayered coatings.

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Understanding Thermal and A‐Thermal Trapping Processes in Lead Halide Perovskites Towards Effective Radiation Detection Schemes

Rodà

Fasoli

Zaffalon

et al. 2021

Adv Funct Materials

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Lead halide perovskites (LHP) are rapidly emerging as efficient, low-cost, solution-processable scintillators for radiation detection. Carrier trapping is arguably the most critical limitation to the scintillation performance. Nonetheless, no clear picture of the trapping and detrapping mechanisms to/ from shallow and deep trap states involved in the scintillation process has been reported to date, as well as on the role of the material dimensionality.Here, this issue is addressed by performing, for the first time, a comprehensive study using radioluminescence and photoluminescence measurements side-by-side to thermally-stimulated luminescence (TSL) and afterglow experiments on CsPbBr 3 with increasing dimensionality, namely nanocubes, nanowires, nanosheets, and bulk crystals. All systems are found to be affected by shallow defects resulting in delayed intragap emission following detrapping via a-thermal tunneling. TSL further reveals the existence of additional temperature-activated detrapping pathways from deeper trap states, whose effect grows with the material dimensionality, becoming the dominant process in bulk crystals. These results highlight that, compared to massive solids where the suppression of both deep and shallow defects is critical, low dimensional nanostructures are more promising active materials for LHP scintillators, provided that their integration in functional devices meets efficient surface engineering.

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O₂ as a molecular probe for nonradiative surface defects in CsPbBr₃ perovskite nanostructures and single crystals

Abstract: Surface defects and environmental conditions affect the physical properties of CsPbBr3 perovskites differently, based on the materials dimensionality, despite their ‘defect tolerant’ electronic structure.

Cited by 41 publications

References 74 publications

Investigation of the Role of the Environment on the Photoluminescence and the Exciton Relaxation of CsPbBr3 Nanocrystals Thin Films

Investigation of the Role of the Environment on the Photoluminescence and the Exciton Relaxation of CsPbBr3 Nanocrystals Thin Films

Optimizing the Atomic Layer Deposition of Alumina on Perovskite Nanocrystal Films by Using O₂ As a Molecular Probe

Understanding Thermal and A‐Thermal Trapping Processes in Lead Halide Perovskites Towards Effective Radiation Detection Schemes

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O2 as a molecular probe for nonradiative surface defects in CsPbBr3 perovskite nanostructures and single crystals

Abstract: Surface defects and environmental conditions affect the physical properties of CsPbBr3 perovskites differently, based on the materials dimensionality, despite their ‘defect tolerant’ electronic structure.

Cited by 41 publications

References 74 publications

Investigation of the Role of the Environment on the Photoluminescence and the Exciton Relaxation of CsPbBr3 Nanocrystals Thin Films

Investigation of the Role of the Environment on the Photoluminescence and the Exciton Relaxation of CsPbBr3 Nanocrystals Thin Films

Optimizing the Atomic Layer Deposition of Alumina on Perovskite Nanocrystal Films by Using O2 As a Molecular Probe

Understanding Thermal and A‐Thermal Trapping Processes in Lead Halide Perovskites Towards Effective Radiation Detection Schemes

Contact Info

Product

Resources

About

O₂ as a molecular probe for nonradiative surface defects in CsPbBr₃ perovskite nanostructures and single crystals

Optimizing the Atomic Layer Deposition of Alumina on Perovskite Nanocrystal Films by Using O₂ As a Molecular Probe