Reduced Efficiency Roll-Off and Enhanced Stability in Perovskite Light-Emitting Diodes with Multiple Quantum Wells

Yang, Ming; Wang, Nana; Zhang, Shuting; Zou, Wei; He, Yarong; Wei, Yingqiang; Xu, Mengmeng; Wang, Jianpu; Huang, Wei

doi:10.1021/acs.jpclett.8b00600

Cited by 56 publications

(71 citation statements)

References 25 publications

(64 reference statements)

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“…Xie et al demonstrated that the addition of FA + into CsPbBr 3 resulted in an enhanced operational lifetime in perovskite LEDs, which was attributed to a reduced trap density [31]. Yang et al achieved a more significant operational stability improvement with a partial substitution of Cs + in a FA + based perovskite LED [28]. The mixed-cation perovskite LED had a lifetime of ∼31 h in contrast to ∼1 h for the device without Cs + addition under a constant current density of 10 mA cm −2 .…”

Section: A-site Engineeringmentioning

confidence: 99%

“…However, due to the low field present during operation, ion migration does not appear to be a severe problem affecting the operational lifetime of perovskite PVs [27]. On the contrary, it is not uncommon to see a perovskite LED degrades to half of their initial efficiency within hours [16,18,28,29] or even minutes [17,[30][31][32][33][34] due to ion migration under an applied electric field. In addition, perovskite can undergo electrochemical reactions driven by charge injection, leading to interfacial degradation and perovskite decomposition [35].…”

Section: Introductionmentioning

confidence: 99%

“…Therefore, ion migration, electrochemical reactions and interfacial reactions are the first order degradation mechanisms in perovskite LEDs, and operational stability is a major obstacle that perovskite LEDs need to overcome. While efforts have been devoted to improving the operational stability through compositional engineering, defect engineering and device architecture engineering [28][29][30][31][32][33], very little progress has been made to date. In order to accelerate this progress, a comprehensive understanding on the degradation mechanisms in the operation of perovskite LEDs is needed.…”

Section: Introductionmentioning

confidence: 99%

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Operational stability of perovskite light emitting diodes

et al. 2020

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Organometal halide perovskite light emitting diodes (LEDs) have attracted a lot of attention in recent years, owing to the rapid progress in device efficiency. However, their short operational lifetime severely impedes the practical uses of these devices. The operating stability of perovskite LEDs are due to degradation due to ambient environment and degradation during operation. The former can be suppressed by encapsulation while the latter one is the intrinsic degradation due to the electrochemical stability of the perovskite materials. In addition, perovskites also suffer from ion migration which is a major degradation mechanism in perovskite LEDs. In this review, we specifically focus on the operational stability of perovskite LEDs. The review is divided into two parts: the first part contains a summary of various degradation mechanisms and some insight on the degradation behavior and the second part is the strategies how to improve the operational stability, especially the strategies to suppress ion migration. Based on the current advances in the literature, we finally present our perspectives to improve the device stability.

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Section: A-site Engineeringmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Operational stability of perovskite light emitting diodes

et al. 2020

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“…We believe this is probably resulting from two reasons: 1) a slow trap‐filling process by the injected carriers and/or ionic motion; 2) a slow internal field‐redistribution due to local ionic motion of excess ions under external electric field . The device EQE EL decays to half of the initial value after ≈96 h of continuous operation at a given current density of 200 mA cm −2 , creating a new record of operation lifetime for perovskite LEDs, and even better than the best performing near infrared organic LEDs . For a higher injection current density of 1000 mA cm −2 , the operation lifetime of quasi‐2D perovskite LED still reaches an impressed 5.35 h. Our results suggest that the good stability of the LED devices can be attributed to the intrinsic stability of quasi‐2D perovskite films with high crystallinity and a low level of defects.…”

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confidence: 99%

Oriented Quasi‐2D Perovskites for High Performance Optoelectronic Devices

et al. 2018

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device stability impedes its commercialization, mainly stemming from the chemical decomposition of regular 3D perovskites in damp environment. [3,4] Encapsulation techniques can slow down the degradation process, but the essential approach to tackle this issue is to find stable perovskite materials capable of achieving long-term stability. [5] In contrast to traditional 3D counterparts, quasi-2D layered perovskites have shown enhanced stability owing to the bulkier and hydrophobic organic molecule in the structure, and have been applied both in photovoltaics and light-emitting diodes. [6][7][8][9] Quasi-2D perovskites take the generic structural formula of L 2 S n−1 M n X 3n+1 , where n is an integer, M is a divalent metal, X is a halide anion, and L and S are organic cations with large and small sizes, respectively. [10] Layered structures are usually formed by inserting the large-sized organic cation spacers into the inorganic sheets of corner-sharing [MX 6 ] octahedra. These quasi-2D compounds can be regarded as natural formed quantum-well (QW) structures, in which the semiconducting inorganic sheets act as the wells and the organic dielectric layers correspond to the Quasi-2D layered organometal halide perovskites have recently emerged as promising candidates for solar cells, because of their intrinsic stability compared to 3D analogs. However, relatively low power conversion efficiency (PCE) limits the application of 2D layered perovskites in photovoltaics, due to large energy band gap, high exciton binding energy, and poor interlayer charge transport. Here, efficient and water-stable quasi-2D perovskite solar cells with a peak PCE of 18.20% by using 3-bromobenzylammonium iodide are demonstrated. The unencapsulated devices sustain over 82% of their initial efficiency after 2400 h under relative humidity of ≈40%, and show almost unchanged photovoltaic parameters after immersion into water for 60 s. The robust performance of perovskite solar cells results from the quasi-2D perovskite films with hydrophobic nature and a high degree of electronic order and high crystallinity, which consists of both ordered large-bandgap perovskites with the vertical growth in the bottom region and oriented smallbandgap components in the top region. Moreover, due to the suppressed nonradiative recombination, the unencapsulated photovoltaic devices can work well as light-emitting diodes (LEDs), exhibiting an external quantum efficiency of 3.85% and a long operational lifetime of ≈96 h at a high current density of 200 mA cm −2 in air.

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“…b,c) External quantum efficiency (EQE (%)) and luminescence of the best reported LEDs plotted as a function of injection current density. The data are plotted using the reported EQE values, and luminescence for red/NIR and green, blue, and orange PeLEDs. For details of each device and its performance parameters, refer to Table .…”

Section: Introductionmentioning

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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Reduced Efficiency Roll-Off and Enhanced Stability in Perovskite Light-Emitting Diodes with Multiple Quantum Wells

Cited by 56 publications

References 25 publications

Operational stability of perovskite light emitting diodes

Operational stability of perovskite light emitting diodes

Oriented Quasi‐2D Perovskites for High Performance Optoelectronic Devices

Inorganic and Layered Perovskites for Optoelectronic Devices

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