Suchergebnisse

The development of perovskite emitters, their use in light-emitting devices, and the challenges in enhancing the efficiency and stability, as well as reducing the potential toxicity of this technology are discussed in this Review. Metal halide perovskites have shown promising optoelectronic properties suitable for light-emitting applications. The development of perovskite light-emitting diodes (PeLEDs) has progressed rapidly over the past several years, reaching high external quantum efficiencies of over 20%. In this Review, we focus on the key requirements for high-performance PeLEDs, highlight recent advances on materials and devices, and emphasize the importance of reliable characterization of PeLEDs. We discuss possible approaches to improve the performance of blue and red PeLEDs, increase the long-term operational stability and reduce toxicity hazards. We also provide an overview of the application space made possible by recent developments in high-efficiency PeLEDs. ; Funding Agencies|European Research Council Starting GrantEuropean Research Council (ERC) [717026]; Swedish Energy Agency EnergimyndighetenSwedish Energy Agency [48758-1]; Swedish Foundation for International Cooperation in Research and Higher Education [CH2018-7736]; Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University (Faculty Grant SFO-Mat-LiU) [2009-00971]; UK Engineering and Physical Sciences Research CouncilEngineering & Physical Sciences Research Council (EPSRC); Joint Research Program between China and the European Union [2016YFE0112000]; National Key Research and Development Program of China [2016YFB0401600]; National Natural Science Foundation of ChinaNational Natural Science Foundation of China (NSFC) [21975220, 91833303, 91733302, 51911530155]

Colloidal metal oxide nanocrystals offer a unique combination of excellent low-temperature solution processability, rich and tuneable optoelectronic properties and intrinsic stability, which makes them an ideal class of materials as charge transporting layers in solution-processed light-emitting diodes and solar cells. Developing new material chemistry and custom-tailoring processing and properties of charge transporting layers based on oxide nanocrystals hold the key to boosting the efficiency and lifetime of all-solution-processed light-emitting diodes and solar cells, and thereby realizing an unprecedented generation of high-performance, low-cost, large-area and flexible optoelectronic devices. This review aims to bridge two research fields, chemistry of colloidal oxide nanocrystals and interfacial engineering of optoelectronic devices, focusing on the relationship between chemistry of colloidal oxide nanocrystals, processing and properties of charge transporting layers and device performance. Synthetic chemistry of colloidal oxide nanocrystals, ligand chemistry that may be applied to colloidal oxide nanocrystals and chemistry associated with post-deposition treatments are discussed to highlight the ability of optimizing processing and optoelectronic properties of charge transporting layers. Selected examples of solution-processed solar cells and light-emitting diodes with oxide-nanocrystal charge transporting layers are examined. The emphasis is placed on the correlation between the properties of oxide-nanocrystal charge transporting layers and device performance. Finally, three major challenges that need to be addressed in the future are outlined. We anticipate that this review will spur new material design and simulate new chemistry for colloidal oxide nanocrystals, leading to charge transporting layers and solution-processed optoelectronic devices beyond the state-of-the-art. ; Funding Agencies|National Key Research and Development Program of China [2016YFB0401602, 2016YFA0204000]; National Natural Science Foundation of China [51522209, 91433204, U1632118, 21571129]; Fundamental Research Funds for the Central Universities [2015FZA3005]; Shanghai Key Research program [16JC1402100]; Shanghai International Cooperation Project [16520720700]; Carl Tryggers Stiftelse; Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linko "ping University [2009-00971]

Solution-processable perovskites show highly emissive and good charge transport, making them attractive for low-cost light-emitting diodes (LEDs) with high energy conversion efficiencies. Despite recent advances in device efficiency, the stability of perovskite LEDs is still a major obstacle. Here, we demonstrate stable and bright perovskite LEDs with high energy conversion efficiencies by optimizing formamidinium lead iodide films. Our LEDs show an energy conversion efficiency of 10.7%, and an external quantum efficiency of 14.2% without outcoupling enhancement through controlling the concentration of the precursor solutions. The device shows low efficiency droop, i.e. 8.3% energy conversion efficiency and 14.0% external quantum efficiency at a current density of 300 mA cm(-2), making the device more efficient than state-of-the-art organic and quantum-dot LEDs at high current densities. Furthermore, the half-lifetime of device with benzylamine treatment is 23.7 hr under a current density of 100 mA cm(-2), comparable to the lifetime of near-infrared organic LEDs. ; Funding Agencies|Joint Research Program between China and European Union [2016YFE0112000]; Major Research Plan of the National Natural Science Foundation of China [91733302]; National Basic Research Program of China-Fundamental Studies of Perovskite Solar Cells [2015CB932200]; Natural Science Foundation of Jiangsu Province, China [BK20150043, BK20150064, BK20180085]; National Key R&D Program of China [2016YFB0401600, 2017YFB0404500, 2018YFB0406704]; National Natural Science Foundation of China [11474164, 61875084, 61634001, 51522209, 91433204]; National Science Fund for Distinguished Young Scholars [61725502]; Major Program of Natural Science Research of Jiangsu Higher Education Institutions of China [18KJA510002]; Synergetic Innovation Center for Organic Electronics and Information Displays; Natural Science Foundation of Zhejiang Province, China [LY17A040008]

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. ; Funding Agencies|ERC Starting GrantEuropean Research Council (ERC) [717026]; European Commission Marie Skodowska-Curie Actions [691210]; Swedish Foundation for International Cooperation in Research and Higher Education [CH2018-7736]; Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University [2009-00971]; China Scholarship CouncilChina Scholarship Council; Jardine Foundation; Cambridge Trust; Linkoping University

Organometal halide perovskites can be processed from solutions at low temperatures to form crystalline direct-bandgap semiconductors with promising optoelectronic properties(1-5). However, the efficiency of their electroluminescence is limited by non-radiative recombination, which is associated with defects and leakage current due to incomplete surface coverage(6-9). Here we demonstrate a solution-processed perovskite light-emitting diode (LED) based on self-organized multiple quantum wells (MQWs) with excellent film morphologies. The MQW-based LED exhibits a very high external quantum efficiency of up to 11.7%, good stability and exceptional highpower performance with an energy conversion efficiency of 5.5% at a current density of 100 mA cm(-2). This outstanding performance arises because the lower bandgap regions that generate electroluminescence are effectively confined by perovskite MQWs with higher energy gaps, resulting in very efficient radiative decay. Surprisingly, there is no evidence that the large interfacial areas between different bandgap regions cause luminescence quenching. ; Funding Agencies|National Basic Research Program of China-Fundamental Studies of Perovskite Solar Cells [2015CB932200]; Natural Science Foundation of Jiangsu Province, China [BK20131413, BK20140952, BM2012010]; National Natural Science Foundation of China [11474164, 51522209, 91433204, 61405091, 11474249]; National 973 Program of China [2015CB654901]; Jiangsu Specially-Appointed Professor programme; Synergetic Innovation Center for Organic Electronics and Information Displays; Fundamental Research Funds for the Central Universities [2015FZA3005]; China Postdoctoral Science Foundation; Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University (Faculty Grant SFO-Mat-LiU) [2009-00971]; Swedish Research Council (VR) [330-2014-6433]; European Commission Marie Sklodowska-Curie actions [691210, INCA 600398]