Influence of the image charge effect on excitonic energy structure in organic-inorganic multiple quantum well crystals

Takagi, Hidetsugu; Kunugita, Hideyuki; Ema, Kazuhiro

doi:10.1103/physrevb.87.125421

Cited by 66 publications

(89 citation statements)

References 25 publications

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“…7–12 Here, the low dielectric constant of the adjacent organic layers provides poor shielding of the electrons and holes in the inorganic layers leading to the exciton's dielectric confinement. The E b values for n = 1 perovskites are typically above 300 meV, 13 comparable to those of certain organic molecules. 14 These tightly bound excitons in 2D perovskites have enabled varied applications in luminescence.…”

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confidence: 90%

Decreasing the electronic confinement in layered perovskites through intercalation

et al. 2017

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Section: Introductionmentioning

confidence: 90%

Decreasing the electronic confinement in layered perovskites through intercalation

et al. 2017

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“…Electronic coupling between inorganic layers is negligible because of the high energy barriers formed by the PEA layers. This 2D material naturally forms repeating quantum well structures, as schematically shown in Figure 1B, that tightly confine excitons within the inorganic layers, leading to high exciton binding energies (350 -480 meV) 37 and strong, stable PL at room temperature. 36 Narrow, violet PL was previously reported for (PEA)2PbBr4.…”

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confidence: 99%

Color-Pure Violet-Light-Emitting Diodes Based on Layered Lead Halide Perovskite Nanoplates

et al. 2016

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Violet electroluminescence is rare in both inorganic and organic light-emitting diodes (LEDs). Low-cost and room-temperature solution-processed lead halide perovskites with high-efficiency and color-tunable photoluminescence are promising for LEDs. Here, we report room-temperature color-pure violet LEDs based on a two-dimensional lead halide perovskite material, namely, 2-phenylethylammonium (C6H5CH2CH2NH3(+), PEA) lead bromide [(PEA)2PbBr4]. The natural quantum confinement of two-dimensional layered perovskite (PEA)2PbBr4 allows for photoluminescence of shorter wavelength (410 nm) than its three-dimensional counterpart. By converting as-deposited polycrystalline thin films to micrometer-sized (PEA)2PbBr4 nanoplates using solvent vapor annealing, we successfully integrated this layered perovskite material into LEDs and achieved efficient room-temperature violet electroluminescence at 410 nm with a narrow bandwidth. This conversion to nanoplates significantly enhanced the crystallinity and photophysical properties of the (PEA)2PbBr4 samples and the external quantum efficiency of the violet LED. The solvent vapor annealing method reported herein can be generally applied to other perovskite materials to increase their grain size and, ultimately, improve the performance of optoelectronic devices based on perovskite materials.

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“…Therefore, we can estimate ¦ LT at 4 K to be 7 meV. It is reported that ¦ LT and the exciton binding energy of the two-dimensional perovskite lead bromide material (C 4 H 9 NH 3 ) 2 PbBr 4 are about 70 meV and 390 480 meV, 22,23 respectively. Considering the relation among ¦ LT , the oscillator strength, and the exciton binding energy, 24,25 we can roughly estimate the exciton binding energy of CH 3 NH 3 -PbBr 3 at low temperature to be 80100 meV, which is almost in accordance with the reported value of 76 meV.…”

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Excitonic Feature in Hybrid Perovskite CH3NH3PbBr3 Single Crystals

et al. 2015

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We have measured the temperature dependence of the reflection and photoluminescence spectra of a lead bromide hybrid material (CH 3 NH 3 PbBr 3 ) using high-quality macroscopic single crystals. Single crystals provide clear and sampleindependent reflection spectra that permit discussion of the properties of the photoexcited carriers. We have found that excitons still exist in CH 3 NH 3 PbBr 3 , even at room temperature. We have also determined the temperature dependence of the exciton resonance energy and the line width.In recent years, lead halide organicinorganic hybrid perovskite materials have attracted considerable attention for photovoltaic applications. 16 The reported power conversion efficiencies (PCE) of the hybrid perovskite-type solar cells with lead iodide materials (CH 3 NH 3 PbI 3¹x Cl x ) are more than 20%. Meanwhile, such materials have been studied from the viewpoint that they form ideal low-dimensional systems and have stable excitons. 812 Even in three-dimensional hybrid materials, the exciton binding energies were reported to be 3750 meV. 13This suggests that stable excitons might exist even at room temperature, and seems to contradict the fact that these materials function as excellent photovoltaic materials, for which dissociation of photoexcited electronhole pairs is necessary to extract the photocurrent.While most studies of the excitonic properties have been performed at low temperatures, solar cells work at room temperature. Therefore, in order to resolve the contradiction stated above, it is important to study the temperature dependence of photoexcited carrier properties in these materials. Recent studies of CH 3 NH 3 PbI 3 indicate that the static dielectric constant shows a rapid increase with increasing temperature, suggesting that this effectively decreases the exciton binding energy. 14,15 Consequently, these results support the view that the excitons dissociate at room temperature in CH 3 NH 3 PbI 3 . In order to clarify the intrinsic properties of these materials, however, such investigations should be performed with high-quality single crystals, which are less affected by defects or impurities. Nevertheless, there are few studies on hybrid perovskite single crystals. 1618In this work, we used high-quality macroscopic single crystals of lead bromide hybrid material (CH 3 NH 3 PbBr 3 ), which has similar properties to CH 3 NH 3 PbI 3 but has a larger band gap (ca. 2.35 eV at room temperature).13 Although CH 3 NH 3 PbBr 3 does not absorb near infrared light, a PCE of more than 10% was reported. 19 The reason why we chose CH 3 NH 3 PbBr 3 is that macroscopic single crystals are more easily synthesized than those of CH 3 NH 3 PbI 3 . Using the single crystals, we have measured the temperature dependence of the reflection and photoluminescence (PL) spectra to discuss the properties of the photoexcited carriers. Our results indicate that excitons still exist in CH 3 NH 3 PbBr 3 , even at room temperature. In addition, we have determined the temperature dependence of the exciton reso...

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Influence of the image charge effect on excitonic energy structure in organic-inorganic multiple quantum well crystals

Cited by 66 publications

References 25 publications

Decreasing the electronic confinement in layered perovskites through intercalation

Decreasing the electronic confinement in layered perovskites through intercalation

Color-Pure Violet-Light-Emitting Diodes Based on Layered Lead Halide Perovskite Nanoplates

Excitonic Feature in Hybrid Perovskite CH3NH3PbBr3 Single Crystals

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