Multiexciton Lifetime in All-Inorganic CsPbBr<sub>3</sub> Perovskite Nanocrystals

Jong, E. M. L. D. de; Yamashita, G.; Gómez, Leyre; Ashida, Masaaki; Fujiwara, Yoshihiro; Gregorkiewicz, T.

doi:10.1021/acs.jpcc.6b10551

Cited by 51 publications

(61 citation statements)

References 26 publications

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“…3 could be fitted with a double and triple exponential function for below and above CM threshold pumping respectively. This yields τ 1 = ~ 89 ps for the fast component for above threshold pumping which agrees with previously reported time constants for the AR process 43 , 53 , 54 . After the multi-exciton relaxation process, a single exciton remains, which decays through non-radiative and radiative recombination processes, depending on the characteristics of individual NCs, (because the ensemble PL QY < 100%) giving rise to the slow decay.…”

Section: Resultssupporting

confidence: 90%

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: Resultssupporting

confidence: 90%

Efficient carrier multiplication in CsPbI3 perovskite nanocrystals

et al. 2018

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“…It is noticed that a much faster decay than that of single‐exciton recombination appears under high excitation intensities, corresponding to nonradiative biexciton Auger recombination. Similar phenomena are also observed for CsPbX 3 nanocrystals of other halides . By subtraction of the single‐exciton recombination, the biexciton Auger lifetime is determined to be less than 100 ps for CsPbBr 3 nanocrystals with a size of ≈10 nm.…”

Section: Photophysics Of Cspbx3 Nanocrystalssupporting

confidence: 70%

“…Ultrafast TA spectroscopy can provide complementary information to time‐revolved PL experiments. Up to now, the TA measurements of CsPbX 3 nanocrystals have been widely investigated by several groups . Wu et al, for the first time, investigated the carrier dynamics of CsPbBr 3 nanocrystals using a femtosecond white‐light pump‐probe system .…”

Section: Photophysics Of Cspbx3 Nanocrystalsmentioning

confidence: 99%

All‐Inorganic Metal Halide Perovskite Nanostructures: From Photophysics to Light‐Emitting Applications

Wang

Sun

2017

Small Methods

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decay arising from the defect-state trapping dominates carrier recombination, which results in a typically low photoluminescence quantum yield (PLQY) (<30%), especially under low carrier-injection densities (≈10 15 cm −3 ), comparable to that under LED working conditions. [5,6,[12][13][14][15] Hence, spontaneous free-carrier generation following light absorption in OIHPs, which explains the high photoconversion efficiency, becomes the obstacle to improving their light-emission performance.[5] Second, these OIHPs are extremely sensitive to the moisture, oxygen, and heat, which has been found to be closely related to the existence of the organic component, thereby incurring a constraint of a critical environment for fabrication, storage, and device operation, commonly notorious in organic photonic materials.Fortunately, the above limitations of OIHPs can be simultaneously overcome by exploiting all-inorganic metal halide perovskite nanostructures (IHPNs), a closely related family of materials. The all-inorganic constituents with intrinsically higher melting and decomposition points allow improved photo-and thermostability, as well as higher resistance to the atmosphere, and the enhanced exciton binding energies in the perovskite nanostructures ensure stable excitonic emission at room temperature. In early 2015, Protesescu et al. reported pioneering work on all-inorganic cesium lead halide (CsPbX 3 , X = Cl, Br, and I) light-emitting nanocrystals. [16] Immediately after their report, there was an explosion of research activity on IHPNs motivated by their superior optical properties and the low cost of the synthetic methods. [16][17][18] Compared to the canonical CdSe quantum dots, which have developed for more than two decades, [19] the emerging all-inorganic CsPbBr 3 perovskite nanocrystals exhibit even better emission characteristics, including higher PLQY (a PLQY of 100% was recently achieved [20] ) and narrower emission linewidth (<20 nm). [16,18,21,22] Moreover, while a high temperature (280 °C) and a protective atmosphere are required for synthesis of CdSebased quantum dots, the fabrication of CsPbX 3 nanocrystals can be performed at room temperature and free from an inert environment. [18] Leveraging on the halide composition control, the emission wavelength of CsPbX 3 nanocrystals can be finely tuned across the whole visible spectral range, enabling a wide color gamut. [16] Especially, the facile fabrication of high-quality blue-green-emitting (410-530 nm) CsPbX 3 nanocrystals makes them more competitive against traditional metal-chalcogenide nanocrystals, which typically suffer from photodegradation and relatively poor PLQY in the visible short-wavelength range. [16] All-inorganic metal halide perovskite nanostructures (IHPNs) have sparked intense research interest by virtue of their superior optical properties and their cost-effective synthesis. Since the first report in 2015, striking development of IHPNs has been witnessed in terms of fabrication strategies, optical characterization, and optoelectronic a...

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“…With regards to the temperature relaxation at longer time delays, and the slow energy dissipation rate of the FCR, similar behavior is found for both samples, possibly related to a long-living free carrier population, especially in the case of the SC sample. The relaxation bottleneck in H-PVK and I-PVK nanostructures [31][32][33][34][35][36][37][38][39] was recently reported and ascribed to several causes such as efficient Auger processes, hot phonons or polaron formations, that keep the carrier temperature higher than the lattice temperature. However, at the excitation density used in our experiment (δ ≈ 10 16 cm −3 carriers per pulse), both hot phonons and Auger heating are negligible, given the Auger coefficient in CsPbBr 3 bulk, 3 × 10 −27 −4 × 10 −28 cm 6 s −1 [40]; for the same reason, a screening of the exciton-phonon interaction can be excluded.…”

Section: Thermalization Of the Free Carrier Populationmentioning

confidence: 99%

Long-living nonlinear behavior in CsPbBr₃ carrier recombination dynamics

et al. 2019

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By means of time-resolved photoluminescence (TR-PL) spectroscopy, we present a detailed investigation of the carrier relaxation dynamics in a CsPbBr3 bulk sample and microcrystal ensemble at cryogenic temperature on a picosecond time scale. We provide evidence of a long temperature-dependent cooling rate for the excitons and free carriers population, with an initial cooling time constant of a few tens of picoseconds. A relaxation bottleneck in the thermalization process was found that cannot be explained by the Auger effect or hot phonon population, since we address a very low excitation regime, not commonly investigated in literature, where such processes are not effective. Adding a continuous wave optical bias to the picosecond excitation, we probed the photoinduced PL decrease of the localized states and the photoinduced PL increase of the population in the high energy states. A long recovery time from the photoinduced PL decrease was found for localized states and quite significant differences were detected, depending on the resonance/off resonance bias used in the experiment.

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Multiexciton Lifetime in All-Inorganic CsPbBr₃ Perovskite Nanocrystals

Cited by 51 publications

References 26 publications

Efficient carrier multiplication in CsPbI3 perovskite nanocrystals

Efficient carrier multiplication in CsPbI3 perovskite nanocrystals

All‐Inorganic Metal Halide Perovskite Nanostructures: From Photophysics to Light‐Emitting Applications

Long-living nonlinear behavior in CsPbBr₃ carrier recombination dynamics

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Multiexciton Lifetime in All-Inorganic CsPbBr3 Perovskite Nanocrystals

Cited by 51 publications

References 26 publications

Efficient carrier multiplication in CsPbI3 perovskite nanocrystals

Efficient carrier multiplication in CsPbI3 perovskite nanocrystals

All‐Inorganic Metal Halide Perovskite Nanostructures: From Photophysics to Light‐Emitting Applications

Long-living nonlinear behavior in CsPbBr3 carrier recombination dynamics

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Multiexciton Lifetime in All-Inorganic CsPbBr₃ Perovskite Nanocrystals

Long-living nonlinear behavior in CsPbBr₃ carrier recombination dynamics