The thermal stability of FAPbBr<sub>3</sub>nanocrystals from temperature-dependent photoluminescence and first-principles calculations

Wang, Xiaozhe; Wang, Qi; Chai, Zhifang; Wu, Wenzhi

doi:10.1039/d0ra07668f

Cited by 17 publications

(9 citation statements)

References 43 publications

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“…According to previous reports, , the structural phase transition from orthorhombic to tetragonal should be accounted for this red-shift in FAPbBr 3 PeNCs. Moreover, theoretical calculations show that the tetragonal phase has a smaller band gap than the orthorhombic phase, which also supports this observation. It is noted that the phase transition temperature is lower than that in previous research works, , which may be due to the smaller size of the PeNCs. , The blue-shift of emission with temperature from 140 to 295 K can be described by the temperature coefficient α = ∂ E g /∂ T = 0.359 meV/K.…”

Section: Resultssupporting

confidence: 67%

Quasi-Type II Core–Shell Perovskite Nanocrystals for Improved Structural Stability and Optical Gain

Zhang

Guo

et al. 2021

ACS Appl. Mater. Interfaces

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In recent years, core–shell lead halide perovskite nanocrystals (PeNCs) and their devices have attracted intensive attention owing to nearly perfect optoelectronic properties. However, the complex photophysical mechanism among them is still unclear. Herein, monodispersed core–shell PeNCs coated with an all-inorganic cesium lead bromide (CsPbBr3) shell epitaxially grown on the surface of formamidinium lead bromide (FAPbBr3) PeNCs were synthesized. Through power- and temperature-dependent photoluminescence (PL) measurements, it is found that the electronic structure of the core–shell FAPbBr3/CsPbBr3 PeNCs has a quasi-type II band alignment. The presence of Cs+ in the shell limits ion migration and helps to stabilize structural and optical properties. On this basis, after being exposed to pulsed nanosecond laser for a period, an amplified spontaneous emission (ASE) can be observed, which is attributed to the effective passivation induced by laser irradiation on defects at the interface. The ASE threshold of the core–shell PeNCs showing high structural and optical stability is 447 nJ/cm2 under pulsed nanosecond optical pumping. The results that are demonstrated here provide a new idea and perspective for improving the stability of perovskite and can be of practical interest for the utilization of the core–shell PeNCs in optoelectronic devices.

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Section: Resultssupporting

confidence: 67%

Quasi-Type II Core–Shell Perovskite Nanocrystals for Improved Structural Stability and Optical Gain

Zhang

Guo

et al. 2021

ACS Appl. Mater. Interfaces

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“…Despite several efforts, the accurate description of the band gap of halide perovskites with a single formulation of the exchange–correlation functional in DFT is challenging and often results in relatively large errors. For this reason, it is common practice to study each perovskite with an ad hoc DFT hybrid functional specifically designed to reproduce the band gap of that specific perovskite. − Needless to say that this introduces a certain level of empiricism and severely limits the possibility to predict in a reliable way the properties and the band gap of an unknown perovskite, in the attempt to improve the results, it is common practice to include spin–orbit coupling (SOC) effects in the calculations . However, we will show below that this is not always useful and it may result in worsening the agreement with the experiment.…”

Section: Introductionmentioning

confidence: 99%

Density Functional Theory Estimate of Halide Perovskite Band Gap: When Spin Orbit Coupling Helps

2022

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The description of the band gap of halide perovskites at the level of density functional theory (DFT) has been subject of several studies but still presents significant problems and deviations from experimental values. Various approaches have been proposed, including the use of system-specific hybrid functionals with a variable amount of exact exchange or the explicit inclusion of spin–orbit coupling (SOC) effects. In this work, we present a pragmatic recipe to compute the band gap of halide perovskites with a minimum average error. The recipe is tested on a set of 36 halide perovskites of the type ABX3 [A = Cs, methyl-ammonium (MA), and formamidinium (FA); B = Ge, Sn, and Pb; and X = Cl, Br, and I] for which experimental estimates of the band gap have been reported in the literature. Upon assessment of the accuracy of commonly used DFT functionals and the analysis of their performances based on error and statistical analysis, we suggest a strategy to compute band gaps in halide perovskites with a single functional. This is based on the use of the hybrid HSE06 functional where SOC is included exclusively for Pb-containing compounds. The results are rationalized in terms of the materials’ chemical nature and are corroborated by the prediction of their expected efficiencies in solar cells. The calculated efficiencies from band gaps obtained with the proposed approach closely follow the experimental trend, demonstrating the importance of adopting a reliable but material-independent computational strategy to screen new halide perovskite materials for solar energy conversion.

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“…It is well established that organic–inorganic LHP NCs are less stable than all-inorganic LHP NCs at elevated temperatures due to structural phase transition. , Temperature has a great influence on FAPbBr 3 NCs. With the increase of temperature up to 400 K, FAPbBr 3 NCs were easy to change from cubic phase to tetragonal phase . Here, we show that introducing Cs + into organic–inorganic LHP NCs can solve this issue, probably due to the spherical coordination behavior of Cs + compared with asymmetrical FA + cations for the formation of a high-symmetry cubic perovskite structure.…”

Section: Resultsmentioning

confidence: 82%

“…With the increase of temperature up to 400 K, FAPbBr 3 NCs were easy to change from cubic phase to tetragonal phase. 67 Here, we show that introducing Cs + into organic−inorganic LHP NCs can solve this issue, probably due to the spherical coordination behavior of Cs + compared with asymmetrical FA + cations for the formation of a high-symmetry cubic perovskite structure. The 4a), and the PL peak widened and multiple emission peaks appeared, which was an indication of phase transformation and was consistent with previous reports.…”

Section: Resultsmentioning

confidence: 93%

FAPbBr₃/Cs₄PbBr₆ Core/Shell Perovskite Nanocrystals with Enhanced Stability and Emission: Implications for LEDs

Zeng

Chen

Deng

et al. 2022

ACS Appl. Nano Mater.

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Formamidinium lead bromide (FAPbBr3) nanocrystals (NCs) have been demonstrated to exhibit ideal ultrapure green luminescence at 530 nm and to hold great potential in light-emitting diodes, by potentially overcoming the difficulties facing cesium lead bromide (CsPbBr3) NCs. However, compared to all-inorganic lead halide perovskite NCs, organic–inorganic hybrid FAPbBr3 NCs are sensitive to moisture, oxygen, and heat due to their intrinsic instability caused by the organic cations (FA+). Herein, we present an epitaxial growth method for the overgrowth of a large-band-gap cesium lead halide (Cs4PbBr6) shell on the surface of FAPbBr3 NCs. The resulting core/shell NCs show a near-unity photoluminescence quantum yield (PLQY) of 97.1%, the emission with full width at half-maxima of 88 meV, and long-term environmental stability. The introduction of Cs+ into FAPbBr3 NCs can inhibit the migration of FA+ and suppress the phase transformation from cubic phase to tetragonal phase at 60 °C. Furthermore, the existence of shell can provide stronger exciton confinement and improve the thermal stability of FAPbBr3 NCs. The core/shell perovskite NCs developed in this study have the advantages of high PLQY and good stability and may contribute to the field of light-emitting diodes (LEDs).

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The thermal stability of FAPbBr₃nanocrystals from temperature-dependent photoluminescence and first-principles calculations

Abstract: The thermal properties of FAPbBr3 perovskite nanocrystals (PNCs) is investigated by use of temperature-dependent steady-state/time-resolved photoluminescence and first-principle calculations.

Cited by 17 publications

References 43 publications

Quasi-Type II Core–Shell Perovskite Nanocrystals for Improved Structural Stability and Optical Gain

Quasi-Type II Core–Shell Perovskite Nanocrystals for Improved Structural Stability and Optical Gain

Density Functional Theory Estimate of Halide Perovskite Band Gap: When Spin Orbit Coupling Helps

FAPbBr₃/Cs₄PbBr₆ Core/Shell Perovskite Nanocrystals with Enhanced Stability and Emission: Implications for LEDs

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The thermal stability of FAPbBr3nanocrystals from temperature-dependent photoluminescence and first-principles calculations

Abstract: The thermal properties of FAPbBr3 perovskite nanocrystals (PNCs) is investigated by use of temperature-dependent steady-state/time-resolved photoluminescence and first-principle calculations.

Cited by 17 publications

References 43 publications

Quasi-Type II Core–Shell Perovskite Nanocrystals for Improved Structural Stability and Optical Gain

Quasi-Type II Core–Shell Perovskite Nanocrystals for Improved Structural Stability and Optical Gain

Density Functional Theory Estimate of Halide Perovskite Band Gap: When Spin Orbit Coupling Helps

FAPbBr3/Cs4PbBr6 Core/Shell Perovskite Nanocrystals with Enhanced Stability and Emission: Implications for LEDs

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The thermal stability of FAPbBr₃nanocrystals from temperature-dependent photoluminescence and first-principles calculations

FAPbBr₃/Cs₄PbBr₆ Core/Shell Perovskite Nanocrystals with Enhanced Stability and Emission: Implications for LEDs