High‐Efficiency Solution‐Processed Inorganic Metal Halide Perovskite Light‐Emitting Diodes

Cho, Himchan; Wolf, Christoph; Kim, Sang Woo; Woo, Han Young; Bae, Jong Seong; Kim, Hobeom; Heo, Jung-Min; Ahn, Soyeong; Lee, Tae‐Woo

doi:10.1002/adma.201700579

Cited by 203 publications

(153 citation statements)

References 48 publications

(143 reference statements)

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“…Such a surprising phenomenon that the device with low electron transport shows strikingly higher efficiency than the device with good electron transport has not been observed previously, which offers a deep insight into the effect of ETLs in nanocrystal all‐inorganic PeLEDs. Besides, the EQE of Device G4 is higher than or comparable to those of recently reported representative performance levels of CsPbBr 3 PeLEDs (e.g., 1.37% for Cho's device, 1.49% for Zeng's device, and ≤0.93% for other devices). In addition, the maximum luminance of Device G4 is 452 cd m −2 , much higher than that of Device G2 with the conventional ETL TPBi (226 cd m −2 ; Figure S7, Supporting Information).…”

supporting

confidence: 60%

Highly Efficient Green Light‐Emitting Diodes from All‐Inorganic Perovskite Nanocrystals Enabled by a New Electron Transport Layer

Liu

Wang

et al. 2018

Advanced Optical Materials

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and excellent charge-transport capabilities. [1][2][3][4][5] These exceptional properties have also made perovskites suitable for applying to light-emitting diodes (LEDs). [6] Since the first demonstration of hybrid organicinorganic CH 3 NH 3 PbBr 3 perovskite LED (PeLED) in 2014, [7] PeLEDs have rapidly attracted a great deal of attention from both academic and industrial researchers. [8][9][10] So far, the highest external quantum efficiency (EQE) for hybrid organic-inorganic PeLED can reach 11%. [11] However, hybrid organicinorganic perovskite materials suffer from the stability issue, which is a hurdle for the widespread use. Alternatively, all-inorganic perovskites (e.g., CsPbX 3 , X = I, Br, and Cl or mixed halide) possess superior thermal stability than their hybrid counterparts. [12][13][14] Besides, all-inorganic perovskites can exhibit high photoluminescence quantum yield (PLQY, e.g., > 90% in solution) and narrow emissions (e.g., full width at halfmaximum (FWHM) < 30 nm), and are compatible with the solution processing technology, which triggers intense interest in applying all-inorganic perovskites to develop LEDs since the first report of all-inorganic PeLED with a maximum EQE of 0.12% by Adopting proper electron transport layers (ETLs) is essential to high-performance all-inorganic perovskite light-emitting diodes (PeLEDs). However, the effect of ETLs has not been comprehensively investigated in all-inorganic nanocrystal PeLEDs, while 2,2′,2′′-(1,3,5-benzenetriyl) tris-[1-phenyl-1H-benzimidazole] (TPBi) is the most common ETL. Herein, a novel strategy is proposed to enhance the efficiency of nanocrystal PeLEDs. Tris(8-hydroxyquinoline) aluminum (Alq 3 ) is incorporated into TPBi to form a new ETL TPBi/ Alq 3 /TPBi, simultaneously enabling charge balance and confinement. The green PeLED with new ETL exhibits a maximum external quantum efficiency(EQE) of 1.43%, current efficiency of 4.69 cd A −1 , and power efficiency of 1.84 lm W −1 , which are 191%, 192%, and 211% higher than those of PeLEDs with conventional ETL TPBi, respectively. Significantly, the EQE is 36-fold higher than that of PeLED with high electron mobility ETL. Impressively, the full width at half-maximum of electroluminescence emission is 16 nm, which is the narrowest among CsPbBr 3 PeLEDs. The findings may present a rational strategy to enhance the device engineering of all-inorganic PeLEDs. Perovskite LEDsLead halide perovskites have recently emerged as a new family of optoelectronic materials for applications including solar cells, lasers, and photodetectors because of their impressive characteristics including narrow emission, size-tunable optical bandgaps,The ORCID identification number(s) for the author(s) of this article can be found under https://doi.

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confidence: 60%

Highly Efficient Green Light‐Emitting Diodes from All‐Inorganic Perovskite Nanocrystals Enabled by a New Electron Transport Layer

Liu

Wang

et al. 2018

Advanced Optical Materials

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“…As an alternative, all-inorganic perovskites CsPbX 3 (X = I, Br and Cl or mixed halide) show better thermal stabilities, which may overcome the notorious stability issue [129,130,131]. In addition, since all-inorganic perovskites can show narrow emission (e.g., FWHM < 20 nm) and excellent PLQY (e.g., ~100% in solution), they have triggered great interest to develop LEDs [132,133,134,135,136]. After the first LED with all-inorganic perovskites developed in 2015 [137], many methods were used to enhance the performance of this kind of LEDs based on 3D nanocubes [138,139,140].…”

Section: Approaches To Achieve Npl-ledsmentioning

confidence: 99%

Emergence of Nanoplatelet Light-Emitting Diodes

et al. 2018

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Since 2014, nanoplatelet light-emitting diodes (NPL-LEDs) have been emerged as a new kind of LEDs. At first, NPL-LEDs are mainly realized by CdSe based NPLs. Since 2016, hybrid organic-inorganic perovskite NPLs are found to be effective to develop NPL-LEDs. In 2017, all-inorganic perovskite NPLs are also demonstrated for NPL-LEDs. Therefore, the development of NPL-LEDs is flourishing. In this review, the fundamental concepts of NPL-LEDs are first introduced, then the main approaches to realize NPL-LEDs are summarized and the recent progress of representative NPL-LEDs is highlighted, finally the challenges and opportunities for NPL-LEDs are presented.

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“…The factors limiting their performance are presented mainly in two aspects; the morphology of the perovskite films, and the interfaces between the perovskite emission layers and the charge‐injection or transport layers. For a high‐efficiency PeLED, the perovskite emission layer must have high quality morphology with high coverage and low defect density . To passivate defects, reduce ion migration, and fabricate high‐efficiency all‐inorganic PeLEDs, one of the recent effective strategies is to introduce additives into the perovskite layers.…”

Section: Device Parameters Of Peledsmentioning

confidence: 99%

High Brightness and Enhanced Stability of CsPbBr₃‐Based Perovskite Light‐Emitting Diodes by Morphology and Interface Engineering

Guo

et al. 2018

Advanced Optical Materials

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electroluminescent (EL) performance of CH 3 NH 3 PbBr 3 (MAPbBr 3 )-based green PeLED has been greatly boosted from a maximum current efficiency (CE) of 0.3-42.9 cd A −1 . [6][7][8] And the record of the external quantum efficiency (EQE) is 14.36%, which is achieved by a quasi-twodimensional green PeLED. [18] However, despite the rapid improvement of EL performance, the poor moisture and thermal stability of methylamine halide perovskites causes serious deterioration of PeLEDs, limiting their long-term applications. [19,20] Compared with organic-inorganic halide perovskites, all-inorganic halide perovskites, such as cesium lead bromide (CsPbBr 3 ), exhibit not only higher thermal and chemical stability, but also higher PLQY. [21][22][23][24][25] However, the EL efficiency of the CsPbBr 3 -based PeLEDs has yet been inferior to the MAPbBr 3 -based PeLEDs. The factors limiting their performance are presented mainly in two aspects; the morphology of the perovskite films, and the interfaces between the perovskite emission layers and the charge-injection or transport layers. For a high-efficiency PeLED, the perovskite emission layer must have high quality morphology with high coverage and low defect density. [26] To passivate defects, reduce ion migration, and fabricate highefficiency all-inorganic PeLEDs, one of the recent effective strategies is to introduce additives into the perovskite layers. Polymers, such as poly (ethylene oxide) [27,28] and polyethylene glycol, [29] have been employed into the perovskite precursors to passivate defects and suppress ion migration at grain boundaries. Another passivating agent is amine-based small molecules or polymers, [30,31] which also can improve the PLQYs and PL lifetimes of the perovskite films. Although the above passivating agents have the same feature of Lewis base and could produce similar effects on PL and EL improvement, the morphology of these perovskite films are multifarious, which is deduced to be the key of the different EL performance, enhanced with the different additives. However, how to choose the additives to control the perovskite polycrystalline morphology and suppress the defects at grain boundaries is still a big challenge in PeLEDs.In addition to the control of the perovskite morphology to improve EL efficiency, the interface optimization is also vital to the device EL performance, because large A CsPbBr 3 -based all-inorganic perovskite light-emitting diode (PeLED) with ultrahigh brightness and enhanced stability is prepared by controlling of morphology and interface engineering. A nonionic surfactant polyoxyethylene (20) sorbitan monolaurate is introduced into the CsPbBr 3 film, which induces tightly arranged grains in the perovskite film, thus highly passivating the defects at the grain boundaries, resulting in a performance-enhanced PeLED with a highest brightness of 111 000 cd m −2 , a peak current efficiency (CE) of 21.1 cd A −1 , a maximum external quantum efficiency (EQE) of 5.55%, and an operational lifetime of 4.5 h. The device properties are ...

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High‐Efficiency Solution‐Processed Inorganic Metal Halide Perovskite Light‐Emitting Diodes

Cited by 203 publications

References 48 publications

Highly Efficient Green Light‐Emitting Diodes from All‐Inorganic Perovskite Nanocrystals Enabled by a New Electron Transport Layer

Highly Efficient Green Light‐Emitting Diodes from All‐Inorganic Perovskite Nanocrystals Enabled by a New Electron Transport Layer

Emergence of Nanoplatelet Light-Emitting Diodes

High Brightness and Enhanced Stability of CsPbBr₃‐Based Perovskite Light‐Emitting Diodes by Morphology and Interface Engineering

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High‐Efficiency Solution‐Processed Inorganic Metal Halide Perovskite Light‐Emitting Diodes

Cited by 203 publications

References 48 publications

Highly Efficient Green Light‐Emitting Diodes from All‐Inorganic Perovskite Nanocrystals Enabled by a New Electron Transport Layer

Highly Efficient Green Light‐Emitting Diodes from All‐Inorganic Perovskite Nanocrystals Enabled by a New Electron Transport Layer

Emergence of Nanoplatelet Light-Emitting Diodes

High Brightness and Enhanced Stability of CsPbBr3‐Based Perovskite Light‐Emitting Diodes by Morphology and Interface Engineering

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High Brightness and Enhanced Stability of CsPbBr₃‐Based Perovskite Light‐Emitting Diodes by Morphology and Interface Engineering