A Cocktail of Multiple Cations in Inorganic Halide Perovskite toward Efficient and Highly Stable Blue Light-Emitting Diodes

Yuan, Fang; Wu, Zhaoxin; Zhang, Lin; Jiao, Bo; Hou, Xun; Li, Jingrui; Wu, Zhaoxin

doi:10.1021/acsenergylett.9b02562

Cited by 81 publications

(92 citation statements)

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“…The optimization of LiF interlayers and the mechanism of the IPI-structured PeLEDs can be found in our previous works. [38][39][40] The first LiF layer replaces the conventional HTL to improve the hole injection into perovskite emitting layer via tunneling effect. The second LiF layer bridges the perovskite emitting layer and ETLs, as well as prevents the luminescence quenching at the interface ( Figure S15, Supporting Information).…”

Section: Resultsmentioning

confidence: 99%

“…Alkali-metal ions (Rb + and K + ) were added into the inorganic CsPbBr 3 perovskite to passivate trap states and optimize the film quality. Importantly, to suppress electricfield-induced ion migrations, a pair of ultrathin LiF layers were used to sandwich the perovskite emission layer, forming an "insulator-perovskite-insulator" (IPI) device structure, [38][39][40] and a combination of inorganic ZnS/ZnSe were used as cascade ETLs. The impact of these strategies was demonstrated by depth profile analysis of X-ray photoelectron spectroscopy (D-XPS).…”

Section: Introductionmentioning

confidence: 99%

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Suppressing Ion Migration Enables Stable Perovskite Light‐Emitting Diodes with All‐Inorganic Strategy

Zhang

Yuan

et al. 2020

Adv Funct Materials

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2001834 (1 of 8) mobility, and low cost, make this emergent technology very promising. [1-9] Recently, near-infrared and green PeLEDs with external quantum efficiency (EQE) over 20% were reported, [10-13] signifying that we are one step closer to the practical application of PeLEDs in lighting and displays. Several metrics are generally used to assess the performance of PeLEDs. EQE and lifetime are of particular importance among them. Besides, brightness is an intuitive criterion for visible LEDs. [14-16] Most of the previous studies have not yet matched these three metrics simultaneously. For example, the green PeLED with the to-date record-high EQE of 20.3%, the record of PeLEDs so far, had a maximal luminance of 14 000 cd m −2 and 46 h lifetime (measured at continual mode of 100 cd m −2); [11] while for the most stable green PeLED to date (lifetime 250 h measured at initial brightness of 100 cd m −2), the EQE and luminance were 10.5% and 16 436 cd m −2 , respectively. [17] Critical factors that affect the PeLEDs lifetime include the materials stability, the intrinsic defects in perovskites, and most importantly, ion migration within devices. [18-21] Stable perovskites with high luminescence are essential to achieve PeLEDs with both high stability and efficiency. Hybrid organicinorganic perovskites degrade quickly against the heat and environmental moisture. All-inorganic perovskites usually have higher stability, but their PLQY is generally unsatisfactory because of the relatively low film quality. [22] The nonuniform morphology of perovskite films and the high density of defect states are detrimental to the electroluminescence (EL) emission. Intrinsic defects can mediate charge-carrier trapping thus leading to nonradiative recombination loss, which is harmful to the device performance. For efficient PeLEDs with high stability, many efforts have been devoted to reduce the trap states in perovskite films. Introducing large organic ligands is a widely adopted approach, as it can passivate defects and achieve a relatively high film quality by stabilizing the perovskite surfaces or facilitating the formation of low-dimensional perovskites. [13,23-27] Through optimal composition and phase engineering, Yang et al. achieved an EQE of 14.36% and an improved stability for green PeLEDs with quasi-2D perovskites. [27] Meanwhile, Xu et al. demonstrated a highly efficient and stable PeLEDs through the rational design of passivation molecules. [13] The improved stability results from a combination of reduced Joule heating caused by the high efficiency and the suppression of ion migration due to reduced defect density.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Suppressing Ion Migration Enables Stable Perovskite Light‐Emitting Diodes with All‐Inorganic Strategy

Zhang

Yuan

et al. 2020

Adv Funct Materials

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“…The scanning electron microscope (SEM) image of (Cs/Rb)‐PeQDs shows a compact film with good coverage compared to that of Cs‐PeQDs (Figure 1c), indicating the positive effect of Rb doping on film uniformity, [ 22 ] which would be beneficial for device performance in terms of reduction of leakage current. In order to explore the origins of the improved film quality, the X‐ray diffraction (XRD) measurement was further carried out (Figure 1d).…”

Section: Resultsmentioning

confidence: 99%

“…Meanwhile, (Cs/Rb)‐PeQDs film exhibits enhanced intensity of the (100) and (200) peaks compared with Cs‐PeQDs due to the preferential orientation, leading to smoother morphology. [ 22 ] It is worth noting that the diffraction peak shifts to a larger angle upon Rb doping. We attribute this to the smaller ionic radius of Rb cation than that of Cs cation, and the resulting crystal lattice contraction.…”

Section: Resultsmentioning

confidence: 99%

Multiple Cations Enhanced Defect Passivation of Blue Perovskite Quantum Dots Enabling Efficient Light‐Emitting Diodes

Pan

Zhao

Fang

et al. 2020

Advanced Optical Materials

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All inorganic perovskite quantum dots (ABX3, A = Cs, B = Pb, X = Cl, Br, or I) are potential candidates for wide‐color‐gamut display applications. High‐efficiency green and red perovskite quantum dot (PeQD) light‐emitting diodes (LEDs) have been achieved, however, development of blue‐emitting devices, especially those with the relatively short wavelengths (<470 nm) meeting National Television System Committee blue standard, lag largely behind, mainly due to poor film quality, low photoluminescence quantum yield (PLQY) of PeQDs, and unfavorable device structure. Here, a strategy of co‐doping Rb+ and Ni2+ in (Cs0.8Rb0.2)(Pb0.95Ni0.05)(Br1.8Cl1.2) PeQDs is reported to improve the film quality and PLQY of PeQDs by realizing multiple passivations and modifying the energy band of PeQDs to reduce the hole injection barrier. With further engineering the device structure to facilitate the hole transport, PeQDLEDs based on multiple‐cation PeQDs show the maximum EQE of 2.14% and the emission peak at 467 nm with a full width at half maximum of 16 nm. This work would open up a new avenue to design and develop efficient blue‐emitting materials for high‐performance blue PeQDLEDs.

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“…[ 28 ] For instance, a popular compositional strategy has been demonstrated to achieve stable EL spectra for blue PeLEDs on account of the mixture of rubidium (Rb), potassium (K), or formamidine (FA) cations with cesium (Cs) cation. [ 29–31 ]…”

Section: Introductionmentioning

confidence: 99%

Interfacial Potassium‐Guided Grain Growth for Efficient Deep‐Blue Perovskite Light‐Emitting Diodes

Shen

et al. 2020

Adv Funct Materials

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129

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Perovskite light‐emitting diodes (PeLEDs) are emerging candidates for the applications of solution‐processed full‐color displays. However, the device performance of deep‐blue PeLED still lags far behind that of their red and green counterparts, which is largely limited by low external quantum efficiency (EQE) and poor operational stability. Here, a facile and reliable crystallization strategy for perovskite grains is proposed, with improved deep‐blue emission through rational interfacial engineering. By modifying the substrate with potassium cation (K+) as the supplier of heterogeneous nucleation seeds, the interfacial K+‐guided grain growth is realized for well‐packed perovskite assemblies with high surface coverage and the controlled crystal orientation, leading to the enhanced radiative recombination and hole‐transport capabilities. Synergistical boost in device performance is achieved for deep‐blue PeLEDs emitting at 469 nm with a peak EQE of 4.14%, a maximum luminance of 451 cd m–2, and spectrally stable color coordinates of (0.125, 0.076) that matches well with the National Television System Committee (NTSC) standard blue.

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A Cocktail of Multiple Cations in Inorganic Halide Perovskite toward Efficient and Highly Stable Blue Light-Emitting Diodes

Cited by 81 publications

References 50 publications

Suppressing Ion Migration Enables Stable Perovskite Light‐Emitting Diodes with All‐Inorganic Strategy

Suppressing Ion Migration Enables Stable Perovskite Light‐Emitting Diodes with All‐Inorganic Strategy

Multiple Cations Enhanced Defect Passivation of Blue Perovskite Quantum Dots Enabling Efficient Light‐Emitting Diodes

Interfacial Potassium‐Guided Grain Growth for Efficient Deep‐Blue Perovskite Light‐Emitting Diodes

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