Luminescence properties of CsPbBr3 nanocrystals dispersed in a polymer matrix

Demkiv, T.; Myagkota, S. V.; Malyi, T.; Pushak, A.S.; Vistovskyy, V.; Yakibchuk, P. M.; Shapoval, Oleksandr; Mitina, Nataliya; Zaichenko, Alexander; Voloshinovskii, А.

doi:10.1016/j.jlumin.2018.02.021

Cited by 16 publications

(12 citation statements)

References 20 publications

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“…The latter observation is especially insightful: since the experimentally observed cooling time is determined only by the relaxation between the lowest states in bands, this implies that the hot carrier losing its energy by CM is not directly transferred to the lowest state, and that the secondary carrier, created by CM, arrives in a state with a considerably longer relaxation time. We recall that such states (in the form of self-trapped excitons) have been investigated in the past for Si NCs 57 – 59 and have recently been invoked also for IP-NCs 60 . We have also observed that the time constant of this very characteristic prolonged build-up of PIB signal depends on the NC size, shortening for smaller NCs—see Supplementary Fig.…”

Section: Discussionmentioning

confidence: 99%

Efficient carrier multiplication in CsPbI3 perovskite nanocrystals

et al. 2018

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The all-inorganic perovskite nanocrystals are currently in the research spotlight owing to their physical stability and superior optical properties—these features make them interesting for optoelectronic and photovoltaic applications. Here, we report on the observation of highly efficient carrier multiplication in colloidal CsPbI3 nanocrystals prepared by a hot-injection method. The carrier multiplication process counteracts thermalization of hot carriers and as such provides the potential to increase the conversion efficiency of solar cells. We demonstrate that carrier multiplication commences at the threshold excitation energy near the energy conservation limit of twice the band gap, and has step-like characteristics with an extremely high quantum yield of up to 98%. Using ultrahigh temporal resolution, we show that carrier multiplication induces a longer build-up of the free carrier concentration, thus providing important insights into the physical mechanism responsible for this phenomenon. The evidence is obtained using three independent experimental approaches, and is conclusive.

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Section: Discussionmentioning

confidence: 99%

Efficient carrier multiplication in CsPbI3 perovskite nanocrystals

et al. 2018

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“…[15] This phase change is accelerated with harsh washing reagents and, with a more gentle washing strategy-using methyl acetate or MeOAc-CsPbI 3 , is stable in the γ (black) phase for over 2 months. Additionally, several groups have been developing methods of protecting the perovskite structure from moisture, including overlaying silicone resins, [60] preparing polymer or related composites, [61][62][63] and coating with zwitterion [64] or metal complexes. Park et al observe a 16-nm blue shift and eventual degradation in CsPbI 3 nanocrystals that were caused by the irreversible generation of surface defects during photoluminescence measurements.…”

Section: Introductionmentioning

confidence: 99%

“…[54] For films in air, photobrightening followed by photodegradation was observed under illumination, and degradation is also observed for films in dark, ambient conditions. Additionally, several groups have been developing methods of protecting the perovskite structure from moisture, including overlaying silicone resins, [60] preparing polymer or related composites, [61][62][63] and coating with zwitterion [64] or metal complexes. [17,65] A recent report by Liao et al describes the thermal stability of cesium lead halide perovskites from À 190 to 500°C using Raman spectroscopy and XRD.…”

Section: Introductionmentioning

confidence: 99%

Unveiling the Photo‐ and Thermal‐Stability of Cesium Lead Halide Perovskite Nanocrystals

et al. 2019

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Lead halide perovskites possess unique characteristics that are well-suited for optoelectronic and energy capture devices, however, concerns about their long-term stability remain. Limited stability is often linked to the methylammonium cation, and all-inorganic CsPbX 3 (X=Cl, Br, I) perovskite nanocrystals have been reported with improved stability. In this work, the photostability and thermal stability properties of CsPbX 3 (X=Cl, Br, I) nanocrystals were investigated by means of electron microscopy, X-ray diffraction, thermogravimetric analysis coupled with FTIR (TGA-FTIR), ensemble and single particle spectral characterization. CsPbBr 3 was found to be stable under 1-sun illumination for 16 h in ambient conditions, although single crystal luminescence analysis after illumination using a solar simulator indicates that the luminescence states are changing over time. CsPbBr 3 was also stable to heating to 250°C. Large CsPbI 3 crystals (34 � 5 nm) were shown to be the least stable composition under the same conditions as both XRD reflections and Raman bands diminish under irradiation; and with heating the γ (black) phase reverts to the nonluminescent δ phase. Smaller CsPbI 3 nanocrystals (14 � 2 nm) purified by a different washing strategy exhibited improved photostability with no evidence of crystal growth but were still thermally unstable. Both CsPbCl 3 and CsPbBr 3 show crystal growth under irradiation or heat, likely with a preferential orientation based on XRD patterns. TGA-FTIR revealed nanocrystal mass loss was only from liberation and subsequent degradation of surface ligands. Encapsulation or other protective strategies should be employed for long-term stability of these materials under conditions of high irradiance or temperature.[a] B.

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“…Realization of practical LHP NC emitters is critically dependent upon improving their structural, thermodynamical, and optical stability under ambient conditions, which remains the foremost challenge for such nanomaterials (Huang et al, 2017; Kovalenko et al, 2017; Akkerman et al, 2018; Zhao et al, 2018). Encapsulation of perovskite NCs into macro- or nanoscale polymeric structures has been recently demonstrated (Huang et al, 2016; Raja et al, 2016; Wang et al, 2016, 2017; Hou et al, 2017; Lu et al, 2017; Ma et al, 2017; Murphy et al, 2017; Demkiv et al, 2018; Liao et al, 2018; Lin et al, 2018; Sygletou et al, 2018; Tsai et al, 2018; Wong et al, 2018; Xin et al, 2018; Yang M. et al, 2018; Yang S. et al, 2018; Zhang et al, 2018; Zhu et al, 2018) as simple and low-cost methodologies to preserve the LHP NC chemical integrity by suppressing water and oxygen transmission, improving the thermal stability, and reducing structural modifications, to which LHP NCs are highly susceptible, such as ligand desorption and nanocrystal sintering. Furthermore, integration of the NCs into polymers provides a method to improve their solid-state processability into films, microspheres, fibers, or more complex composites while offering new functionalities such as polarizing PL (Raja et al, 2016; Lu et al, 2017), light detection (Wang et al, 2016), biological labeling and sensing (Wang et al, 2017; Zhu et al, 2018) or device applications such as light emitting diodes (Huang et al, 2016; Liao et al, 2018; Lin et al, 2018; Tsai et al, 2018; Xin et al, 2018; Yang M. et al, 2018; Zhang et al, 2018; Zhu et al, 2018).…”

Section: Introductionmentioning

confidence: 99%

Robust Hydrophobic and Hydrophilic Polymer Fibers Sensitized by Inorganic and Hybrid Lead Halide Perovskite Nanocrystal Emitters

et al. 2019

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Advances in the technology and processing of flexible optical materials have paved the way toward the integration of semiconductor emitters and polymers into functional light emitting fabrics. Lead halide perovskite nanocrystals appear as highly suitable optical sensitizers for such polymer fiber emitters due to their ease of fabrication, versatile solution-processing and highly efficient, tunable, and narrow emission across the visible spectrum. A beneficial byproduct of the nanocrystal incorporation into the polymer matrix is that it provides a facile and low-cost method to chemically and structurally stabilize the perovskite nanocrystals under ambient conditions. Herein, we demonstrate two types of robust fiber composites based on electrospun hydrophobic poly(methyl methacrylate) (PMMA) or hydrophilic polyvinylpyrrolidone (PVP) fibrous membranes sensitized by green-emitting all-inorganic CsPbBr 3 or hybrid organic-inorganic FAPbBr 3 nanocrystals. We perform a systematic investigation on the influence of the nanocrystal-polymer relative content on the structural and optical properties of the fiber nanocomposites and we find that within a wide content range, the nanocrystals retain their narrow and high quantum yield emission upon incorporation into the polymer fibers. Quenching of the radiative recombination at the higher/lower bound of the nanocrystal:polymer mass ratio probed is discussed in terms of nanocrystal clustering/ligand desorption due to dilution effects, respectively. The nanocomposite's optical stability over an extended exposure in air and upon immersion in water is also discussed. The studies confirm the demonstration of robust and bright polymer-fiber emitters with promising applications in backlighting for LCD displays and textile-based light emitting devices.

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Luminescence properties of CsPbBr3 nanocrystals dispersed in a polymer matrix

Cited by 16 publications

References 20 publications

Efficient carrier multiplication in CsPbI3 perovskite nanocrystals

Efficient carrier multiplication in CsPbI3 perovskite nanocrystals

Unveiling the Photo‐ and Thermal‐Stability of Cesium Lead Halide Perovskite Nanocrystals

Robust Hydrophobic and Hydrophilic Polymer Fibers Sensitized by Inorganic and Hybrid Lead Halide Perovskite Nanocrystal Emitters

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