Interfacial engineering for highly efficient quasi-two dimensional organic–inorganic hybrid perovskite light-emitting diodes

Liu, Qingwei; Yuan, Shuai; Sun, Shuang‐Qiao; Luo, Wei; Zhang, Yijie; Liao, Liang‐Sheng; Fung, Man‐Keung

doi:10.1039/c8tc06490c

Cited by 48 publications

(43 citation statements)

References 34 publications

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“…[19,120] Apart from improving the wettability of organic films, the PFN-Br layer was shown to result in defect reduction in perovskite films owing to increasing the grain sizes and passivation roles. [19] At present, other buffer layers, including polyvinylpyrrolidone (PVP), [121] ITO 2 -Cl, [20] poly(9-vinylcarbazole) (PVK), [122] perylene, [123] phenethylammonium bromide (PEABr), [124] phenethylammonium iodide (PEAI), [125] 1,3,4,5,7,8-hexafluorotetracyanonaphthoquinodimethane (F 6 TCNQ), [126] and self-assembly monolayers, [127][128][129] are also broadly employed and have proven to improve perovskite grain sizes and morphologies, as we summarized in Table 2.…”

Section: Surface Buffer Materials For Growing Better Perovskitesmentioning

confidence: 99%

Recent Progress on Perovskite Surfaces and Interfaces in Optoelectronic Devices

et al. 2021

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conversion efficiencies (PCEs) of perovskite solar cells (PeSCs) have already surpassed 25%, [4] which is comparable to current industrial-grade mono-crystalline silicon solar cells. This fantastic efficiency combined with potentially low-cost fabrication makes them more attractive than the most efficient photovoltaic technologies. [5] Similarly, perovskite light-emitting diodes (PeLEDs) are shown to have an extraordinary performance with external quantum efficiencies (EQEs) exceeding 20% in devices made from the solution phase at low temperatures. [6][7][8] We associated these notable improvements on device performance with lessons learned from organic optoelectronics and other semiconductor devices. Typically, many empirical approaches learned from others such as structural optimization, [9] interface engineering, [10] defects passivation, [11] etc., have been considered optimizing the carrier injection/extraction and mitigating undesirable non-radiative recombination losses. [12][13][14][15][16] Nonetheless, there is plenty of room optimizing nonradiative recombination losses in the bulk and at the interfaces to reach the efficiency limits. [17,18] Historically, band misalignments and interfacial defects have been considered the predominant factors responsible for the undesirable recombination at the various interfaces in devices. [19][20][21] In light of band misalignment, the resulting nonradiative recombination losses at the perovskite interfaces cause a substantial reduction in open-circuit voltages (V oc ) of the PeSCs, [14] mainly because of charge extraction suppression. For example, an energy barrier height of >0.1 eV is sufficient to block the extraction of majority carriers and to block the minority carriers from entering the undesirable transport layer, resulting in efficiency losses. [22] The presence of a charge injection barrier is also known to impact the turn-on voltage and device efficiency of PeLEDs. [23] Moreover, the deep-level defect-assisted recombination provides an additional path for intrinsic loss of charge carriers. [24][25][26] However, the origin and distribution of deep-level defects, a kind of defect that are far away from the band edge and can trap charge carriers, are highly debated topics. To date, there are several experimental observations confirming that a considerable density of deep-level defects retains at the interfaces of both the single-crystal and polycrystalline devices, and some surface passivation strategies can considerably eliminate the defects on the surfaces. [27][28][29] Based on photoemission Surfaces and heterojunction interfaces, where defects and energy levels dictate charge-carrier dynamics in optoelectronic devices, are critical for unlocking the full potential of perovskite semiconductors. In this progress report, chemical structures of perovskite surfaces are discussed and basic physical rules for the band alignment are summarized at various perovskite interfaces. Common perovskite surfaces are typically decorated by various compositional and structur...

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Section: Surface Buffer Materials For Growing Better Perovskitesmentioning

confidence: 99%

Recent Progress on Perovskite Surfaces and Interfaces in Optoelectronic Devices

et al. 2021

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“…Interface engineering is also an effective strategy to improve device performance. 27,28 Liu et al 29 (EQE) of 11.1%) green PeLED by employing betaine, whose molecules possess both amphiphilicity and conjugation functions, as the interface buffer layer; Yang and co-workers 30 presented surface-passivation engineering of quasi-2D perovskite films by means of trioctylphosphine oxide (TOPO) treatment and obtained a 14.36% EQE for the resultant greenemitting device. Herein, we demonstrate high-performance quasi-2D Pe-LEDs by incorporating a vacuum-deposition lithium fluoride (LiF) interlayer between the perovskite layer and the electrontransporting layer (ETL) to simultaneously reduce exciton loss and improve charge balance.…”

Section: ■ Introductionmentioning

confidence: 99%

Improving Efficiency and Stability in Quasi-2D Perovskite Light-Emitting Diodes by a Multifunctional LiF Interlayer

You

Wang

Cao

et al. 2020

ACS Appl. Mater. Interfaces

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Owing to the enlarged exciton binding energy and the ability to confine charge carriers compared to their three-dimensional (3D) counterparts, research on quasi-two-dimensional (quasi-2D) perovskite materials and the correlative application in light-emitting diodes (LEDs) has attracted considerable attention. However, high density of defects, exciton emission trapping, and unbalanced charge injection are still the main intractable obstacles to their further development and practical application. Herein, we report an efficient multifunctional interlayer, lithium fluoride (LiF), to boost the performance of green-emitting quasi-2D perovskite LEDs (PeLEDs) by simultaneously overcoming the aforementioned issues. The introduced LiF interlayer not only eliminates the defects at perovskite grain boundaries and the surface by reinforcing the chemical bonds with uncoordinated lead ions but also restrains the emission of perovskite from quenching triggered by the electron transport layer and reduces excess electron injections to effectively balance carriers in the device. As a result, the resulting green quasi-2D PeLED shows a maximum external quantum efficiency of 16.35%, which is the best value obtained for quasi-2D perovskite-based LEDs reported so far, with simultaneous improvement in the operating lifetime of the device.

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“…[ 31 ] We note that the film with direct annealing exhibits almost no photoluminance, which is probably due to the formation of a large number of electronic defects in the 3D crystals that induce significant nonradiative recombination. [ 32–38 ]…”

Section: Resultsmentioning

confidence: 99%

Vacuum‐Assisted Preparation of High‐Quality Quasi‐2D Perovskite Thin Films for Large‐Area Light‐Emitting Diodes

Chen

Zeng

Jiang

et al. 2021

Adv Funct Materials

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Recent years have witnessed marked progress in the electroluminescence efficiency of perovskite-based light emitting diodes (PeLEDs). Nevertheless, the majority of highly efficient devices feature only several square millimeters with the perovskite emitting layers deposited by nonscalable methods, which hinders their intriguing application in large-area lightings and displays. Here, a robust crystallization protocol is devised for the deposition of high-quality perovskite emitting layers by blade coating. Central to this method is the deployment of a vacuum process to the freshly coated precursor film, thereby achieving controllable crystallization kinetics by decoupling precursor deposition and the subsequent thermal annealing. Accordingly, dense and uniform perovskite thin films with efficient energy funneling among the evenly distributed 2D and 3D phases are obtained. PeLED devices based on the vacuum-processed quasi-2D cesium lead tribromide layers achieve high external quantum efficiencies of 8.24% and 6.12% on active areas of 0.12 and 1 cm 2 , respectively. The scalability of the technology is further demonstrated by fabricating a 3.5 × 3.5 cm 2 device with bright and uniform emitting characteristic. This work offers a viable approach for further advancing the performance of large-area PeLEDs by scalable methods.

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Interfacial engineering for highly efficient quasi-two dimensional organic–inorganic hybrid perovskite light-emitting diodes

Abstract: Metal halide-based perovskites are regarded as promising candidates for light-emitting diodes (LEDs) owing to their high color purity, tunable bandgap and solution processability.

Cited by 48 publications

References 34 publications

Recent Progress on Perovskite Surfaces and Interfaces in Optoelectronic Devices

Recent Progress on Perovskite Surfaces and Interfaces in Optoelectronic Devices

Improving Efficiency and Stability in Quasi-2D Perovskite Light-Emitting Diodes by a Multifunctional LiF Interlayer

Vacuum‐Assisted Preparation of High‐Quality Quasi‐2D Perovskite Thin Films for Large‐Area Light‐Emitting Diodes

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