Stable and bright formamidinium-based perovskite light-emitting diodes with high energy conversion efficiency

Miao, Yanfeng; Ke, You; Wang, Nana; Zou, Wei; Xu, Mengmeng; Cao, Yu; Sun, Yan; Yang, Rong; Wang, Ying; Tong, Yunfang; Xu, Wenjie; Zhang, Liangdong; Li, Renzhi; Li, Jing; He, Haiping; Jin, Yizheng; Gao, Feng; Huang, Wei; Wang, Jianpu

doi:10.1038/s41467-019-11567-1

Cited by 113 publications

(61 citation statements)

References 34 publications

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“…However, the EL intensities of aged device (magenta line) are lower than those of fresh device (red line), suggesting the formation of EL quenchers. Note that the EL quenchers do not influence the PL intensity, which may be explained by the degradation of the interfaces between the emissive layer and charge-transport layers 34 . In addition, we find obvious emission from TFB (400 to 500 nm) when the driving voltage is above 2.5 V (Supplementary Fig.…”

Section: Discussionmentioning

confidence: 96%

Perovskite-molecule composite thin films for efficient and stable light-emitting diodes

et al. 2020

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Although perovskite light-emitting diodes (PeLEDs) have recently experienced significant progress, there are only scattered reports of PeLEDs with both high efficiency and long operational stability, calling for additional strategies to address this challenge. Here, we develop perovskite-molecule composite thin films for efficient and stable PeLEDs. The perovskite-molecule composite thin films consist of in-situ formed high-quality perovskite nanocrystals embedded in the electron-transport molecular matrix, which controls nucleation process of perovskites, leading to PeLEDs with a peak external quantum efficiency of 17.3% and half-lifetime of approximately 100 h. In addition, we find that the device degradation mechanism at high driving voltages is different from that at low driving voltages. This work provides an effective strategy and deep understanding for achieving efficient and stable PeLEDs from both material and device perspectives.

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Section: Discussionmentioning

confidence: 96%

Perovskite-molecule composite thin films for efficient and stable light-emitting diodes

et al. 2020

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“…63 The optical absorption spectra, which are extracted from the diffuse reflectance spectra by the Kubelka-Munk function, exhibit a gradual shift of the absorption edge to lower energy as Cl is replaced by Br and followed by I in Cs2SnX6 parents. Considering a direct bandgap property for these semiconducting materials, 64 the optical bandgap values are extracted from the linear region in the Tauc plot of (αhν) 2 against energy ( Figure S3). (Figure 2a and Table 1).…”

Section: Introductionmentioning

confidence: 99%

Uncovering Halide Mixing and Octahedral Dynamics in Vacancy-Ordered Double Perovskites by Multinuclear Magnetic Resonance Spectroscopy

Karmakar¹,

Mukhopadhyay²,

Gachod³

et al. 2021

Preprint

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Vacancy-ordered double perovskites Cs2SnX6 (X = Cl, Br, I) have emerged as promising lead-free and ambient-stable materials for photovoltaic and optoelectronic applications. To advance these promising materials, it is crucial to determine the correlations between physical properties and their local structure and dynamics. Solid-state NMR spectroscopy of multiple NMR-active nuclei (133Cs, 119Sn and 35Cl) in these cesium tin(IV) halides has been used to decode the structure, which plays a key role in the materials’ optical properties. The 119Sn NMR chemical shifts span approximately 4000 ppm and the 119Sn spin-lattice relaxation times span three orders of magnitude when the halogen goes from chlorine to iodine in these diamagnetic compounds. Moreover, ultrawideline 35Cl NMR spectroscopy for Cs2SnCl6 indicates an axially symmetric chlorine electric field gradient tensor with a large quadrupolar coupling constant of ca. 32 MHz, suggesting a chlorine that is directly attached to Sn(IV) ions. Variable temperature 119Sn spin lattice relaxation time measurements uncover the presence of hidden dynamics of octahedral SnI6 units in Cs2SnI6 with a low activation energy barrier of 12.45 kJ/mol (0.129 eV). We further show that complete mixed-halide solid solutions of Cs2SnClxBr6−x and Cs2SnBrxI6−x (0 ≤ x ≤ 6) form at any halogen compositional ratio. 119Sn and 133Cs NMR spectroscopy resolve the unique local SnClnBr6−nand SnBrnI6−n (n = 0−6) octahedral and CsBrmI12−m (m = 0−12) cuboctahedral environments in the mixed-halide samples. The experimentally observed 119Sn NMR results are consistent with magnetic shielding parameters obtained by density functional theory computations to verify random halogen distribution in mixed-halide analogues. Finally, we demonstrate the difference in the local structures and optical absorption properties of Cs2SnI6 samples prepared by solvent-assisted and solvent-free synthesis routes.

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“…The second approach to achieve blue emission perovskites is through mixing Br and Cl in three-dimensional (3D) perovskites [ 12 ]. The 3D perovskites possess the merits of high charge mobility and low luminescence quenching at high excitations, which have been proven to be an effective strategy to achieve bright LEDs with high energy conversion efficiency [ 4 , 6 , 13 ]. However, phase segregation in mixed-halide 3D perovskites is generally found to prevent the achievement of spectrally stable LED devices [ 12 ].…”

Section: Introductionmentioning

confidence: 99%

Halide Homogenization for High-Performance Blue Perovskite Electroluminescence

Lü

Tong

et al. 2020

Research

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Metal halide perovskite light-emitting diodes (LEDs) have achieved great progress in recent years. However, bright and spectrally stable blue perovskite LED remains a significant challenge. Three-dimensional mixed-halide perovskites have potential to achieve high brightness electroluminescence, but their emission spectra are unstable as a result of halide phase separation. Here, we reveal that there is already heterogeneous distribution of halides in the as-deposited perovskite films, which can trace back to the nonuniform mixture of halides in the precursors. By simply introducing cationic surfactants to improve the homogeneity of the halides in the precursor solution, we can overcome the phase segregation issue and obtain spectrally stable single-phase blue-emitting perovskites. We demonstrate efficient blue perovskite LEDs with high brightness, e.g., luminous efficacy of 4.7, 2.9, and 0.4 lm W-1 and luminance of over 37,000, 9,300, and 1,300 cd m-2 for sky blue, blue, and deep blue with Commission Internationale de l’Eclairage (CIE) coordinates of (0.068, 0.268), (0.091, 0.165), and (0.129, 0.061), respectively, suggesting real promise of perovskites for LED applications.

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Stable and bright formamidinium-based perovskite light-emitting diodes with high energy conversion efficiency

Cited by 113 publications

References 34 publications

Perovskite-molecule composite thin films for efficient and stable light-emitting diodes

Perovskite-molecule composite thin films for efficient and stable light-emitting diodes

Uncovering Halide Mixing and Octahedral Dynamics in Vacancy-Ordered Double Perovskites by Multinuclear Magnetic Resonance Spectroscopy

Halide Homogenization for High-Performance Blue Perovskite Electroluminescence

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