| 1. |
- Xu, Weidong, 1988-, et al.
(author)
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Rational molecular passivation for high-performance perovskite light-emitting diodes
- 2019
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In: Nature Photonics. - : Springer Nature Publishing AG. - 1749-4885 .- 1749-4893. ; 13:6, s. 418-424
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Journal article (peer-reviewed)abstract
- A major efficiency limit for solution-processed perovskite optoelectronic devices, for example light-emitting diodes, is trap-mediated non-radiative losses. Defect passivation using organic molecules has been identified as an attractive approach to tackle this issue. However, implementation of this approach has been hindered by a lack of deep understanding of how the molecular structures influence the effectiveness of passivation. We show that the so far largely ignored hydrogen bonds play a critical role in affecting the passivation. By weakening the hydrogen bonding between the passivating functional moieties and the organic cation featuring in the perovskite, we significantly enhance the interaction with defect sites and minimize non-radiative recombination losses. Consequently, we achieve exceptionally high-performance near-infrared perovskite light-emitting diodes with a record external quantum efficiency of 21.6%. In addition, our passivated perovskite light-emitting diodes maintain a high external quantum efficiency of 20.1% and a wall-plug efficiency of 11.0% at a high current density of 200 mA cm−2, making them more attractive than the most efficient organic and quantum-dot light-emitting diodes at high excitations.
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| 2. |
- Bao, Chunxiong, 1986-, et al.
(author)
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A multifunctional display based on photo-responsive perovskite light-emitting diodes
- 2024
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In: NATURE ELECTRONICS. - : NATURE PORTFOLIO. - 2520-1131.
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Journal article (peer-reviewed)abstract
- Current display screens are typically only used for information display, but can have a range of different sensors integrated into them for functions such as touch control, ambient light sensing and fingerprint sensing. Photo-responsive light-emitting diodes (LEDs), which can display information and respond to light excitation, could be used to develop future ultra-thin and large screen-to-body ratio screens. However, photo-response is difficult to achieve with conventional display technologies. Here, we report a multifunctional display that uses photo-responsive metal halide perovskite LEDs as pixels. The perovskite LED display can be simultaneously used as a touch screen, ambient light sensor and image sensor (including for fingerprint drawing) without integrating any additional sensors. The light-to-electricity conversion efficiency of the pixels also allow the display to act as a photovoltaic device that can charge the equipment. Photo-responsive metal halide perovskite light-emitting diodes can be used to create a multifunctional display that can function as a touch screen, ambient light sensor and image sensor.
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| 3. |
- Yuan, Zhongcheng, 1989-
(author)
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Defects and crystallinity control of perovskite films for light-emitting diodes
- 2019
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Doctoral thesis (other academic/artistic)abstract
- Metal halide perovskites are promising materials for the fabrication of cost-effective and highperformance light-emitting diodes (LEDs), due to their solution processability, high photoluminescence quantum efficiencies (PLQEs) and excellent charge transport properties. Importantly, perovskite LEDs show ultra-pure emission color, which is better than that of the state-of-the-art quantum dot LEDs (QLEDs) and organic LEDs (OLEDs), demonstrating a bright application potential for realizing vivid natural colors display in the future.In this thesis, we first incorporate natural molecules, e.g. deoxyribonucleic acid (DNA), to passivate FAPbI3 perovskite films. We notice that the existence of carbonyl and amide groups within DNA are important for efficient passivation of perovskite films. Combining the knowledge, we further introduce amino-functionalized molecules into perovskite films and achieve significantly improved efficiency of 21.6 %, which is a record external quantum efficiency (EQE) of perovskite LEDs. We reveal that by weakening the hydrogen bond strength between passivation molecules and organic cations, the interaction between passivation amino groups and defects improves, contributing to more efficient passivation.We also notice that the underlying substrates play important roles on the film quality of perovskite and the device performance of the ensuing LEDs. Here, we reveal that efficient deprotonation of the undesirable organic cations (Methylammonium (MA+) or Formamidinium (FA+)) by a metal oxide interlayer, e.g. ZnO, with a high isoelectric point, is critical to promote the transition from intermediate phases to highly emissive perovskites. We reveal synergistic effects of precursor stoichiometry and interfacial reactions for high-performance perovskite LEDs, and establish useful guidelines for rational device optimisation. With the knowledge we obtain from the deprotonation process, we further push the EL emission from near-infrared (NIR) (around 800 nm) region to deep red emission (around 700 nm) via cation exchange process between cesium (Cs+) and FA+, which promotes enhanced crystallization of the perovskite films and devices performance simultaneously.Intensive efforts in the perovskite community have pushed the EQEs of perovskite LEDs to over 20 %for green, red and NIR emission region. However, it is still a long way to go before their practical applications. We believe that efficient control of both the defects and crystallinity of the perovskite films through rational materials development and interfacial modifications is important for the development of perovskite optoelectronic devices. In addition, both our findings on the perovskite film quality control are universal and provide insights to promote the development of perovskites (especially the hybrid ones containing organic components) for the applications of other optoelectronic devices.
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| 4. |
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| 5. |
- Zou, Yatao, et al.
(author)
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Protocol for efficient and self-healing near-infrared perovskite light-emitting diodes.
- 2022
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In: STAR protocols. - : Cell Press. - 2666-1667. ; 3:3
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Journal article (peer-reviewed)abstract
- Preparation of highly efficient and stable perovskite light-emitting diodes (PeLEDs) with reproducible device performance is challenging. This protocol describes steps for fabrication of high-performance and self-healing PeLEDs. These include instructions for synthesis of charge-transporting zinc oxide (ZnO) nanocrystals, step-by-step device fabrication, and control over self-healing of the degraded devices. For complete details on the use and execution of this protocol, please refer to Teng et al. (2021).
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