18 research outputs found

    Solution-processed perovskite light emitting diodes with efficiency exceeding 15% through additive-controlled nanostructure tailoring.

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    Organometal halide perovskites (OHP) are promising materials for low-cost, high-efficiency light-emitting diodes. In films with a distribution of two-dimensional OHP nanosheets and small three-dimensional nanocrystals, an energy funnel can be realized that concentrates the excitations in highly efficient radiative recombination centers. However, this energy funnel is likely to contain inefficient pathways as the size distribution of nanocrystals, the phase separation between the OHP and the organic phase. Here, we demonstrate that the OHP crystallite distribution and phase separation can be precisely controlled by adding a molecule that suppresses crystallization of the organic phase. We use these improved material properties to achieve OHP light-emitting diodes with an external quantum efficiency of 15.5%. Our results demonstrate that through the addition of judiciously selected molecular additives, sufficient carrier confinement with first-order recombination characteristics, and efficient suppression of non-radiative recombination can be achieved while retaining efficient charge transport characteristics

    Protocol for efficient and self-healing near-infrared perovskite light-emitting diodes.

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    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).Funding agencies: RC Starting Grant (no. 717026), the Swedish Energy AgencyEnergimyndigheten (no. 48758-1), and the Swedish Government Strategic Research Area in Mate-rials Science on Functional Materials Linko ̈ ping University (Faculty Grant SFO-Mat-LiU no. 2009-00971). Y.Z. and B.S. also thank the support from Macau SAR (file no. 0044/2021/A)</p

    Energy-Saving Synthesis of MOF-Derived Hierarchical and Hollow Co(VO<sub>3</sub>)<sub>2</sub>‑Co(OH)<sub>2</sub> Composite Leaf Arrays for Supercapacitor Electrode Materials

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    A one-step and energy-saving method was proposed to synthesize hierarchical and hollow Co­(VO<sub>3</sub>)<sub>2</sub>-Co­(OH)<sub>2</sub> composite leaf arrays on carbon cloth, which expressed high capacitance (522 mF cm<sup>–2</sup> or 803 F g<sup>–1</sup> at the current density of 0.5 mA cm<sup>–2</sup>), good rate capability (79.5% capacitance retention after a 30-fold increase of the current density) and excellent cycling stability (90% capacitance retention after 15 000 charge–discharge cycles) when tested as a supercapacitor electrode

    High-Performance Perovskite Light-Emitting Diode with Enhanced Operational Stability Using Lithium Halide Passivation

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    Defect passivation has been demonstrated to be effective in improving the radiative recombination of charge carriers in perovskites, and consequently, the device performance of the resultant perovskite light-emitting diodes (LEDs). State-of-the-art useful passivation agents in perovskite LEDs are mostly organic chelating molecules that, however, simultaneously sacrifice the charge-transport properties and thermal stability of the resultant perovskite emissive layers, thereby deteriorating performance, and especially the operational stability of the devices. We demonstrate that lithium halides can efficiently passivate the defects generated by halide vacancies and reduce trap state density, thereby suppressing ion migration in perovskite films. Efficient green perovskite LEDs based on all-inorganic CsPbBr3 perovskite with a peak external quantum efficiency of 16.2 %, as well as a high maximum brightness of 50 270 cd m(-2), are achieved. Moreover, the device shows decent stability even under a brightness of 10(4) cd m(-2). We highlight the universal applicability of defect passivation using lithium halides, which enabled us to improve the efficiency of blue and red perovskite LEDs.Funding Agencies|National Key Research and Development Program of China [2016YFA0202402]; National Natural Science Foundation of ChinaNational Natural Science Foundation of China [61974098, 61674108]; Jiangsu High Educational Natural Science Foundation [18KJA430012]; Priority Academic Program Development of Jiangsu Higher Education Institutions; 111 programMinistry of Education, China - 111 Project; Collaborative Innovation Center of Suzhou Nano Science and Technology (NANO-CIC); China Scholarship CouncilChina Scholarship Council [201806920071]; Postgraduate Research and Practice Innovation Program of Jiangsu Province [KYCX18_2504]</p

    Thermal-induced interface degradation in perovskite light-emitting diodes

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    Perovskite light-emitting diodes (PeLEDs) have experienced rapid improvements in device efficiency during the last several years. However, the operational instability of PeLEDs remains a key barrier hindering their practical applications. A fundamental understanding of the degradation mechanism is still lacking but will be important to seek ways to mitigate these unwanted processes. In this work, through comprehensive characterizations of the perovskite emitters and the interfacial contacts, we figure out that Joule heating induced interface degradation is one of the dominant factors affecting the operational stability of PeLEDs. We investigate the interfacial contacts of PeLEDs based on a commonly used device structure, with an organic electron transport layer of 1,3,5-tris(N-phenylbenzimiazole-2-yl)benzene (TPBi), and observe obvious photoluminescence quenching of the perovskite layer after device operation. Detailed characterizations of the interlayers and the interfacial contacts reveal that photoluminescence quenching is mainly due to the element inter-diffusion at the interface induced by the morphological evolution of the TPBi layers under Joule heating during the operation of PeLEDs. Our work provides direct insights into the degradation pathways and highlights the importance of exploring intrinsically stable interlayers as well as interfacial contacts beyond the state-of-the-art to further boost the operational stability of PeLEDs.Funding Agencies|National Natural Science Foundation of ChinaNational Natural Science Foundation of China (NSFC) [91833303, 61974098, 61674108]; National Key Research and Development Program [2016YFA0201900]; Priority Academic Program Development of Jiangsu Higher Education Institutions; 111 programMinistry of Education, China - 111 Project; Collaborative Innovation Center of Suzhou Nano Science and Technology (NANO-CIC); ERC Starting GrantEuropean Research Council (ERC) [717026]; Swedish Energy Agency EnergimyndighetenSwedish Energy Agency [48758-1]; Swiss National Science Foundation (SNF)-Bridge POWERSwiss National Science Foundation (SNSF) [20B2-1_176552/1]; Postgraduate Research &amp; Practice Innovation Program of Jiangsu Province [KYCX18_2504]; China Scholarship CouncilChina Scholarship Council [201806920071]</p
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