The Physics of Light Emission in Halide Perovskite Devices

Stranks, Samuel D.; Hoye, Robert L. Z.; Di, Dawei; Friend, Richard H.; Deschler, Felix

doi:10.1002/adma.201803336

Cited by 218 publications

(220 citation statements)

References 154 publications

(182 reference statements)

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“…The internal quantum efficiency (IQE) measures the fraction of injected electrons that lead to generation of a photon. To reach a high IQE, quenching of electron–hole pairs at the interface between the active layer and the surrounding layers has to be avoided, and no charges should pass through the device without recombining radiatively, and therefore, efficient LEDs often employ electron and hole blocking layers to avoid opposite charges reaching the injecting electrodes, which would lead to high ELQY . This could also be achieved by employing electron injecting layer (EIL) with a low‐lying valance band so as to minimize hole injection, and hole injecting layer (HIL) with high‐lying conduction band edge (or LUMO in the case of organic molecules), to avoid electron injection .…”

Section: Applications Of Inorganic and Layered Perovskite Materialsmentioning

confidence: 99%

Inorganic and Layered Perovskites for Optoelectronic Devices

et al. 2019

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Organic-inorganic halide perovskites are making breakthroughs in a range of optoelectronic devices. Reports of >23% certified power conversion efficiency in photovoltaic devices, external quantum efficiency >21% in light-emitting diodes (LEDs), continuous-wave lasing and ultralow lasing thresholds in optically pumped lasers, and detectivity in photodetectors on a par with commercial GaAs rivals are being witnessed, making them the fastest ever emerging material technology. Still, questions on their toxicity and long-term stability raise concerns toward their market entry. The intrinsic instability in these materials arises due to the organic cation, typically the volatile methylamine (MA), which contributes to hysteresis in the current-voltage characteristics and ion migration. Alternative inorganic substitutes to MA, such as cesium, and large organic cations that lead to a layered structure, enhance structural as well as device operational stability. These perovskites also provide a high exciton binding energy that is a prerequisite to enhance radiative emission yield in LEDs. The incorporation of inorganic and layered perovskites, in the form of polycrystalline films or as single-crystalline nanostructure morphologies, is now leading to the demonstration of stable devices with excellent performance parameters. Herein, key developments made in various optoelectronic devices using these perovskites are summarized and an outlook toward stable yet efficient devices is presented.

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Section: Applications Of Inorganic and Layered Perovskite Materialsmentioning

confidence: 99%

Inorganic and Layered Perovskites for Optoelectronic Devices

et al. 2019

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“…It should be noted that the PLQY results are limited by the outcoupling efficiency. The outcoupling efficiency for MAPbI 3 flat film was found to be 6.7% . This limits the achievable external PLQY in flat thin films samples .…”

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confidence: 91%

“…Ruddlesden–Popper (RP) organic–inorganic halide perovskites have been attracting increasing attention for applications in high efficiency light emitting diodes (LEDs) due to their wider range of tunability, improved environmental stability, and higher exciton binding energy compared to more commonly studied 3D organic–inorganic halide perovskites . They have a general formula Aʹ 2 A n ‐1 B n X 3 n +1 , where Aʹ is the bulky organic spacer cation, A is Cs + or a smaller organic cation capable of forming a 3D perovskite ABX 3 , B is a divalent metal cation (Pb, Sn), X is a halide anion, while n is the number of perovskite sheets between Aʹ spacer cations.…”

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confidence: 99%

Spontaneous Formation of Nanocrystals in Amorphous Matrix: Alternative Pathway to Bright Emission in Quasi‐2D Perovskites

Liu

Chan

et al. 2019

Advanced Optical Materials

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Ruddlesden-Popper (RP) organic-inorganic halide perovskites have been attracting increasing attention for applications in high efficiency light emitting diodes (LEDs) due to their wider range of tunability, improved environmental stability, and higher exciton binding energy compared to more commonly studied 3D organic-inorganic halide perovskites. [1][2][3][4][5][6][7][8][9][10][11][12][13][14] They have a general formula Aʹ 2 A n-1 B n X 3n+1 , where Aʹ is the bulky organic spacer cation, A is Cs + or a smaller organic cation capable of forming a 3D perovskite ABX 3 , B is a divalent metal cation (Pb, Sn), X is a halide anion, while n is the number of perovskite sheets between Aʹ spacer cations. A number of different RP perovskite materials have been reported to date, with the most commonly studied ones using butylammonium (BA) or phenethylammonium (PEA) spacer cations. [1] Thin films of a quasi-2D perovskite will commonly contain domains with different n. [3,6] Therefore, significant efforts in the study of Significant enhancement of the light emission in Ruddlesden-Popper organic-inorganic halide perovskites is obtained by antisolvent induced spontaneous formation of nanocrystals in an amorphous matrix. This morphology change results in the passivation of defects and significant enhancement of light emission and 16 times higher photoluminescence quantum yield (PLQY), and it is applicable to different spacer cations. The use of trioctylphosphine oxide results in further defect passivation leading to an increase in PLQY (≈2.3 times), the suppression of lower energy emission in low temperature photoluminescence spectra, the dominance of radiative recombination, and the disappearance of thermal quenching of the luminescence. The proposed method offers a reproducible, controllable, and antisolvent-insensitive alternative to energy landscape engineering to utilize energy funneling phenomenon to achieve bright emission. Instead of facilitating fast energy transfer from lower to higher number of perovskite sheets to prevent nonradiative losses, it is demonstrated that defects can be effectively passivated via morphology control and the use of a passivating agent, so that bright emission can be obtained from single phase nanocrystals embedded in amorphous matrix, resulting in light emitting diodes with a maximum external quantum efficiency of 2.25%. Ruddlesden-Popper PerovskitesThe ORCID identification number(s) for the author(s) of this article can be found under https://doi.www.advopticalmat.de Science and Technology of the People's Republic of China through Croatian-Chinese bilateral projects entitled "Insight into thermosalient phenomenon of molecular crystals-one step closer to revealing the jumping mystery using the high-temperature AFM and high-temperature FTIR" and "The study of highly stable and mixed cations organometallic trihalide perovskite materials and solar cells."

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“…Metal halide perovskites have attracted extensive attention in the field of light‐emitting diodes (LEDs) due to their excellent luminescence efficiency, balanced charge transport, high color purity, tunable bandgap, and low‐cost solution processability . Very recently, the external quantum efficiency (EQE) of green‐ and near‐infrared‐emitting perovskite LEDs (PeLEDs) have reached over 20%, which is becoming competitive with that of conventional quantum dot LEDs and organic LEDs.…”

Section: Introductionmentioning

confidence: 99%

Spectrally Stable Ultra‐Pure Blue Perovskite Light‐Emitting Diodes Boosted by Square‐Wave Alternating Voltage

Tan

Luo

Yang

et al. 2019

Advanced Optical Materials

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perspective. [1,14] The blue-emitting PeLEDs are indispensable for full-color displays and solid-state lighting, especially the pure blue emitting around 467 nm according to the National Television System Committee (NTSC) criterion. [15,16] Therefore, it is worthwhile for researchers to achieve pure blue-emitting PeLEDs.Two main strategies have been proposed to realize blue-emitting PeLEDs. Controlling quantum well structure provides a simple approach to tune the emission spectrum by engineering organic component composition. [17] For example, quasi-2D perovskite PEA 2 (Cs x MA 1−x ) n−1 Pb n Br 3n+1 can adjust the emission wavelength by controlling 〈n〉 value through partially replacing phenethylamine (PEA) by isopropylamine (IPA). [18] When the largest 〈n〉 value in the quantum well structure is tuned at 3 exactly, this perovskite film can exhibit 464 nm photoluminescence (PL), resulting in a low EQE of 0.15% with an EL peak at 474 nm due to lower conductivity of incorporated IPA than PEA. The 〈n〉 value = 3 is difficult to control, as the perovskite composition is not only affected by the spin-coating procedure, but also by the substrate, often resulting in a large distribution of 〈n〉 values.On the other hand, the mixed halide approach can achieve tunable emission from 450 to 490 nm with high photoluminescence quantum yields (PLQYs) by simply controlling Br/Cl ratio. [19] Yao et al. reported a 0.07% EQE of blue PeLEDs with an EL peak at 470 nm based on CsPbBr x Cl 3−x nanocrystals. [20] Congreve et al. improved EQE to 2.12% with an EL peak located at 466 nm by optimizing the device structure and Mn doping in CsPbBr x Cl 3−x nanocrystals. [21] Li et al. realized an efficient sky-blue PeLED with an EL peak located at 480 nm by incorporating PEABr to passivate CsPbBr x Cl 3−x film. [22] However, the strong working electric field (over a magnitude of 10 5 V cm −1 ) would prompt the halide-ion-migration-induced phase separation of mixed halide perovskite, which shifts the EL spectrum from target pure blue to longer wavelength. The spectral instability under working bias is the biggest challenge for mixed halide approach.According to our experience, it is easier and more controllable to achieve pure blue-emitting perovskite through the mixed halide approach than controlling quantum well structure. As for the spectral instability, the mixed halide perovskite film shows Cl-rich and Br-rich region under working bias due to the halide ions migration, and we found out that the process is Perovskite light-emitting diodes (PeLEDs) have attracted great research interests considering their excellent luminescent properties and solution processability. Despite rapid advances of green-, red-, and near-infraredemitting PeLEDs, blue-PeLEDs, as an essential part for full-color display and solid-state lighting, still remain challenging due to their low efficiency and spectral instability. Here, reported are spectrally stable blue-PeLEDs biased by an alternating voltage. First, 2-phenoxyethylamine-passivated CsPbBr x Cl 3−x is obtained...

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The Physics of Light Emission in Halide Perovskite Devices

Cited by 218 publications

References 154 publications

Inorganic and Layered Perovskites for Optoelectronic Devices

Inorganic and Layered Perovskites for Optoelectronic Devices

Spontaneous Formation of Nanocrystals in Amorphous Matrix: Alternative Pathway to Bright Emission in Quasi‐2D Perovskites

Spectrally Stable Ultra‐Pure Blue Perovskite Light‐Emitting Diodes Boosted by Square‐Wave Alternating Voltage

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