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  • 1.
    Argillander, Joakim
    et al.
    Linköping University, Department of Electrical Engineering, Information Coding. Linköping University, Faculty of Science & Engineering.
    Alarcon, Alvaro
    Linköping University, Department of Electrical Engineering, Information Coding. Linköping University, Faculty of Science & Engineering.
    Bao, Chunxiong
    Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials. Linköping University, Faculty of Science & Engineering. Nanjing Univ, Peoples R China.
    Kuang, Chaoyang
    Linköping University, Faculty of Science & Engineering. Linköping University, Department of Science and Technology, Laboratory of Organic Electronics.
    Lima, Gustavo
    Univ Concepcion, Chile.
    Gao, Feng
    Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials. Linköping University, Faculty of Science & Engineering.
    Xavier, Guilherme B.
    Linköping University, Department of Electrical Engineering, Information Coding. Linköping University, Faculty of Science & Engineering.
    Quantum random number generation based on a perovskite light emitting diode2023In: Communications Physics, E-ISSN 2399-3650, Vol. 6, no 1, article id 157Article in journal (Refereed)
    Abstract [en]

    True random number generation is not thought to be possible using a classical approach but by instead exploiting quantum mechanics genuine randomness can be achieved. Here, the authors demonstrate a certified quantum random number generation using a metal-halide perovskite light emitting diode as a source of weak coherent polarisation states randomly producing an output of either 0 or 1. The recent development of perovskite light emitting diodes (PeLEDs) has the potential to revolutionize the fields of optical communication and lighting devices, due to their simplicity of fabrication and outstanding optical properties. Here we demonstrate that PeLEDs can also be used in the field of quantum technologies by implementing a highly-secure quantum random number generator (QRNG). Modern QRNGs that certify their privacy are posed to replace classical random number generators in applications such as encryption and gambling, and therefore need to be cheap, fast and with integration capabilities. Using a compact metal-halide PeLED source, we generate random numbers, which are certified to be secure against an eavesdropper, following the quantum measurement-device-independent scenario. The obtained generation rate of more than 10 Mbit s(-1), which is already comparable to commercial devices, shows that PeLEDs can work as high-quality light sources for quantum information tasks, thus opening up future applications in quantum technologies.

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  • 2.
    Argillander, Joakim
    et al.
    Linköping University, Department of Electrical Engineering, Information Coding. Linköping University, Faculty of Science & Engineering.
    Alarcon, Alvaro
    Linköping University, Department of Electrical Engineering, Information Coding. Linköping University, Faculty of Science & Engineering.
    Bao, Chunxiong
    Nanjing Univ, Peoples R China.
    Kuang, Chaoyang
    Linköping University, Department of Science and Technology, Laboratory of Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Lima, Gustavo
    Univ Concepcion, Chile; Millennium Inst Res Opt, Chile.
    Gao, Feng
    Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials. Linköping University, Faculty of Science & Engineering.
    Xavier, Guilherme B
    Linköping University, Department of Electrical Engineering, Information Coding. Linköping University, Faculty of Science & Engineering.
    Secure quantum random number generation with perovskite photonics2024In: QUANTUM COMPUTING, COMMUNICATION, AND SIMULATION IV, SPIE-INT SOC OPTICAL ENGINEERING , 2024, Vol. 12911, article id 129111BConference paper (Refereed)
    Abstract [en]

    In the field of cryptography, it is crucial that the random numbers used in key generation are not only genuinely random but also private, meaning that no other party than the legitimate user must have information about the numbers generated. Quantum random number generators can offer both properties - fundamentally random output, as well as the ability to implement generators that can certify the amount of private randomness generated, in order to remove some side-channel attacks. In this study we introduce perovskite technology as a resilient platform for photonics, where the resilience is owed to perovskite's ease of manufacturing. This has the potential to mitigate disruptions in the supply chain by enabling local and domestic manufacturing of photonic devices. We demonstrate the feasibility of the platform by implementing a measurement-device independent quantum random number generator based on perovskite LEDs.

  • 3.
    Banerjee, Debashree
    et al.
    Linköping University, Department of Science and Technology, Laboratory of Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Hallberg, Tomas
    FOI Swedish Def Res Agcy, Sweden.
    Chen, Shangzhi
    Linköping University, Department of Science and Technology, Laboratory of Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Kuang, Chaoyang
    Linköping University, Department of Science and Technology, Laboratory of Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Liao, Mingna
    Linköping University, Department of Science and Technology, Laboratory of Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Kariis, Hans
    FOI Swedish Def Res Agcy, Sweden.
    Jonsson, Magnus
    Linköping University, Department of Science and Technology, Laboratory of Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Electrical tuning of radiative cooling at ambient conditions2023In: Cell Reports Physical Science, E-ISSN 2666-3864, Vol. 4, no 2, article id 101274Article in journal (Refereed)
    Abstract [en]

    Passive radiative cooling forms a sustainable means for cooling of objects through thermal radiation. Along with progress on static cooling systems, there is an emerging need for dynamic control to enable thermoregulation. Here, we demonstrate temperature regu-lation of devices at ambient pressure and temperature by electri-cally tuning their radiative cooling power. Our concept exploits the possibility to electrochemically tune the thermal emissivity and thereby cooling power of a conducting polymer, which enabled reversible control of device temperatures of around 0.25 degrees C at ambient conditions in a sky simulator. Besides tuneable radiative cooling by exposure to the sky, the concept could also contribute to reduced needs for indoor climate control by enabling dynamic control of thermal energy flows between indoor objects, such as be-tween people and walls.

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  • 4.
    Cai, Weidong
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials. Linköping University, Faculty of Science & Engineering.
    Kuang, Chaoyang
    Linköping University, Department of Science and Technology, Laboratory of Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Liu, Tianjun
    Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials. Linköping University, Faculty of Science & Engineering.
    Shang, Yuequn
    Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials. Linköping University, Faculty of Science & Engineering.
    Zhang, Jia
    Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials. Linköping University, Faculty of Science & Engineering.
    Qin, Jiajun
    Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials. Linköping University, Faculty of Science & Engineering.
    Gao, Feng
    Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials. Linköping University, Faculty of Science & Engineering.
    Multicolor light emission in manganese-based metal halide composites2022In: Applied Physics Reviews, E-ISSN 1931-9401, Vol. 9, no 4, article id 041409Article in journal (Refereed)
    Abstract [en]

    Manganese-based organic-inorganic metal halide composites have been considered as promising candidates for lead-free emitters. However, in spite of their excellent luminescence properties in green and red regions, blue emission-a critical component for white light generation-from pristine manganese-based composites is currently missing. In this work, we successfully achieve blue luminescence center in manganese-based composites through selecting specific organic component methylbenzylamine (MBA). Our approach is fundamentally different from green and red emission in manganese-based composites, which result from manganese-halide frameworks. The coexistence of different luminescence centers in our manganese-based composites is confirmed by photoluminescence (PL) and photoluminescence excitation (PLE) results. As a result of different photoluminescence excitation responses of different emission centers, the resulting emission color can be tuned with selecting different excitation wavelengths. Specifically, a white light emission can be obtained with Commission Internationale de leclairage coordinates of (0.33, 0.35) upon the 330 nm excitation. We further demonstrate the promise of our manganese-based composites in the anti-counterfeiting technology and multicolor lighting. Our results provide a novel strategy for full-spectral emission in manganese-based organic-inorganic metal halide composites and lay a solid foundation for a range of new applications. (C) 2022 Author(s).

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  • 5.
    Chen, Shangzhi
    et al.
    Linköping University, Department of Science and Technology, Laboratory of Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Petsagkourakis, Ioannis
    Linköping University, Department of Science and Technology, Laboratory of Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Spampinato, Nicoletta
    Univ. Bordeaux, CNRS, Bordeaux INP, LCPO, Pessac, France.
    Kuang, Chaoyang
    Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials. Linköping University, Faculty of Science & Engineering.
    Liu, Xianjie
    Linköping University, Department of Science and Technology, Laboratory of Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Brooke, Robert
    RISE Research Institutes of Sweden, Bio- and Organic Electronics, Norrköping, Sweden.
    Kang, Evan S. H.
    Linköping University, Department of Science and Technology, Laboratory of Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Fahlman, Mats
    Linköping University, Department of Science and Technology, Laboratory of Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Crispin, Xavier
    Linköping University, Department of Science and Technology, Laboratory of Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Pavlopoulou, Eleni
    Univ. Bordeaux, CNRS, Bordeaux INP, LCPO, Pessac, France.
    Jonsson, Magnus
    Linköping University, Department of Science and Technology, Laboratory of Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Unraveling vertical inhomogeneity in vapour phase polymerized PEDOT:Tos films2020In: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 8, p. 18726-18734Article in journal (Refereed)
    Abstract [en]

    The conducting polymer poly(3,4-ethylenedioxythiophene) (PEDOT) forms a promising alternative to conventional inorganic conductors, where deposition of thin films via vapour phase polymerization (VPP) has gained particular interest owing to high electrical conductivity within the plane of the film. The conductivity perpendicular to the film is typically much lower, which may be related not only to preferential alignment of PEDOT crystallites but also to vertical stratification across the film. In this study, we reveal non-linear vertical microstructural variations across VPP PEDOT:Tos thin films, as well as significant differences in doping level between the top and bottom surfaces. The results are consistent with a VPP mechanism based on diffusion-limited transport of polymerization precursors. Conducting polymer films with vertical inhomogeneity may find applications in gradient-index optics, functionally graded thermoelectrics, and optoelectronic devices requiring gradient doping.

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  • 6. Order onlineBuy this publication >>
    Kuang, Chaoyang
    Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials. Linköping University, Faculty of Science & Engineering.
    Interface-Assisted Perovskite Modulations for High-Performance Light-Emitting Diodes2021Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Metal halide perovskites have emerged as a class of promising materials for a wide range of optoelectronic devices. Compared with traditional inorganic and organic semiconductors, perovskite materials can be easily processed via solution-based techniques at low temperatures and exhibit high photo-luminescence efficiency, outstanding colour purity, and superior charge transport properties, showing great promise for cost-effective and high-performance light-emitting diodes (LEDs).

    Since the first demonstration of room-temperature operating perovskite-based LEDs (PeLEDs) in 2014, various useful strategies on optimizing perovskite emissive materials and device structures have been developed, leading to notably enhanced device performance of PeLEDs during the last several years. Nevertheless, despite rapid progress in improving the external quantum efficiencies (EQEs) of PeLEDs, which are now approaching those of commercialized technologies, the operational stability of state-of-the-art PeLEDs remains poor, presenting a critical challenge for their practical applications and commercialization. Besides, a majority of the optimization strategies demonstrated for PeLEDs derivate from those developed for either perovskite photovoltaics or prevailing light-emitting technologies, e.g., organic- and quantum-dot-based LEDs. Although these strategies are helpful, more comprehensive investigations and in-depth understanding of factors affecting the property of perovskite emissive layers and the device performance of ensuing PeLEDs are highly desirable to foster further advancements of this promising technology.

    In this thesis, we focus our study on near-infrared PeLEDs based on triiodide perovskite emissive layers processed from precursor solutions. We systematically investigate the critical effects of precursors, substrates, and additives on the film quality of perovskite emissive layers. With the indepth understanding of the perovskite crystallization process, we developed a range of effective interface-assisted strategies on modulating the perovskite emissive layers, which enable us to achieve PeLEDs with high EQEs and excellent long-term operational stability beyond the state-of-the-art.In the first study, we unveiled the synergistic effect of precursor stoichiometry and interfacial reactions for PeLEDs. We reveal that ZnO efficiently deprotonates the organic cations, which promotes the formation of highly emissive perovskites from precursor solution with excess organic components, leading to the achievement of PeLEDs with a high EQE of 19.6 %. In the second study, we presented that such ZnO deprotonation process of excess organic cations can also assist the cation exchange process between cesium-formamidinium (FA-Cs) cation exchange, enabling low-temperature fabrication of pure-phase Cs-FA mixed cation perovskite films with widely tunable emissions peaking between 715 nm and 800 nm as well as high-performance devices with peak EQEs over 15%.

    In spite of enhanced device efficiency realized by the perovskite crystallization modulation, this ZnO deprotonation process places a detrimental effect on the stability of the PeLEDs, which can be accelerated by Joule heating and high electric fields during the device operation. In the third study, we, therefore, demonstrated the role of ZnO in catalyzing an efficient amidation reaction between incorporated dicarboxylic acid additives and excess FAI, preventing the above-mentioned harmful interfacial reaction. With this strategy, the operational half lifetime of the resulting PeLEDs was improved to 682 hours at 20 mA/cm2 while maintaining a high device efficiency of 18.6%.

    In the last work, we emphasized that the rational design of molecular reactions between two additives (diamine and triacrylate) and perovskite components with the assistance of ZnO substrates can subsequently eliminate the negative effect introduced by additive, reduce the defect density and enhance the crystal orientation in the perovskite emissive layers. The rational understanding of interfacial interactions between perovskite, additives, and ZnO, enabled us to achieve PeLEDs with a device efficiency of 23.8% as well as an outstanding operational stability T70 (reduction to 70% of initial efficiency) lifetime of 290 hours at 20 mA/cm2.

    The study in this thesis developed effective interface-assisted modulation strategies for high-quality perovskites towards highly efficient and stable PeLEDs for commercialization. A thorough understanding of perovskite chemistry-property-performance modulation assisted by interfaces is indispensable for the future development of PeLEDs and our study took an important step.

    List of papers
    1. Unveiling the synergistic effect of precursor stoichiometry and interfacial reactions for perovskite light-emitting diodes
    Open this publication in new window or tab >>Unveiling the synergistic effect of precursor stoichiometry and interfacial reactions for perovskite light-emitting diodes
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    2019 (English)In: Nature Communications, E-ISSN 2041-1723, Vol. 10, article id 2818Article in journal (Refereed) Published
    Abstract [en]

    Metal halide perovskites are emerging as promising semiconductors for cost-effective and high-performance light-emitting diodes (LEDs). Previous investigations have focused on the optimisation of the emissive perovskite layer, for example, through quantum confinement to enhance the radiative recombination or through defect passivation to decrease non-radiative recombination. However, an in-depth understanding of how the buried charge transport layers affect the perovskite crystallisation, though of critical importance, is currently missing for perovskite LEDs. Here, we reveal synergistic effect of precursor stoichiometry and interfacial reactions for perovskite LEDs, and establish useful guidelines for rational device optimization. We reveal that efficient deprotonation of the undesirable organic cations by a metal oxide interlayer with a high isoelectric point is critical to promote the transition of intermediate phases to highly emissive perovskite films. Combining our findings with effective defect passivation of the active layer, we achieve high-efficiency perovskite LEDs with a maximum external quantum efficiency of 19.6%.

    Place, publisher, year, edition, pages
    NATURE PUBLISHING GROUP, 2019
    National Category
    Condensed Matter Physics
    Identifiers
    urn:nbn:se:liu:diva-158964 (URN)10.1038/s41467-019-10612-3 (DOI)000473002500007 ()31249295 (PubMedID)
    Note

    Funding Agencies|ERC Starting Grant [717026]; European Commission Marie Sklodowska-Curie Actions [691210]; National Key Research and Development Program of China [2016YFA0202402]; Jiangsu High Educational Natural Science Foundation [18KJA430012]; Priority Academic Program Development of Jiangsu Higher Education Institutions; 111 program; Collaborative Innovation Center of Suzhou Nano Science and Technology (NANO-CIC); China Scholarship Council; National Natural Science Foundation of China [61704077]; Natural Science Foundation of Jiangsu Province [BK20171007]

    Available from: 2019-07-19 Created: 2019-07-19 Last updated: 2023-03-28
    2. Critical role of additive-induced molecular interaction on the operational stability of perovskite light-emitting diodes
    Open this publication in new window or tab >>Critical role of additive-induced molecular interaction on the operational stability of perovskite light-emitting diodes
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    2021 (English)In: Joule, E-ISSN 2542-4351, Vol. 5, no 3, p. 618-630Article in journal (Refereed) Published
    Abstract [en]

    Despite rapid improvements in efficiency and brightness of perovskite light-emitting diodes (PeLEDs), the poor operational stability remains a critical challenge hindering their practical applications. Here, we demonstrate greatly improved operational stability of high-efficiency PeLEDs, enabled by incorporating dicarboxylic acids into the precursor for perovskite depositions. We reveal that the dicarboxylic acids efficiently eliminate reactive organic ingredients in perovskite emissive layers through an in situ amidation process, which is catalyzed by the alkaline zinc oxide substrate. The formed stable amides prohibit detrimental reactions between the perovskites and the charge injection layer underneath, stabilizing the perovskites and the interfacial contacts and ensuring the excellent operational stability of the resulting PeLEDs. Through rationally optimizing the amidation reaction in the perovskite emissive layers, we achieve efficient PeLEDs with a peak external quantum efficiency of 18.6% and a long half-life time of 682 h at 20 mA cm(-2), presenting an important breakthrough in PeLEDs.

    Place, publisher, year, edition, pages
    Cell Press, 2021
    National Category
    Materials Chemistry
    Identifiers
    urn:nbn:se:liu:diva-175082 (URN)10.1016/j.joule.2021.01.003 (DOI)000630098300012 ()
    Note

    Funding Agencies|ERC Starting grantEuropean Research Council (ERC) [717026]; Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University (Faculty Grant SFO-Mat-LiU) [2009-00971]; China Scholarship Council (CSC)China Scholarship Council

    Available from: 2021-04-20 Created: 2021-04-20 Last updated: 2021-12-28Bibliographically approved
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  • 7.
    Kuang, Chaoyang
    et al.
    Linköping University, Department of Science and Technology, Laboratory of Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Chen, Shangzhi
    Linköping University, Department of Science and Technology, Laboratory of Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Luo, Min
    Univ Elect Sci & Technol China, Peoples R China.
    Zhang, Qilun
    Linköping University, Department of Science and Technology, Laboratory of Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Sun, Xiao
    Univ Elect Sci & Technol China, Peoples R China.
    Han, Shaobo
    Wuyi Univ, Peoples R China.
    Wang, Qingqing
    Linköping University, Department of Science and Technology, Laboratory of Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Stanishev, Vallery
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering. Lund Univ, Sweden.
    Darakchieva, Vanya
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering. Lund Univ, Sweden.
    Crispin, Reverant
    Linköping University, Department of Science and Technology, Laboratory of Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Fahlman, Mats
    Linköping University, Department of Science and Technology, Laboratory of Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Zhao, Dan
    Linköping University, Department of Science and Technology, Laboratory of Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Wen, Qiye
    Univ Elect Sci & Technol China, Peoples R China; Univ Elect Sci & Technol China, Peoples R China.
    Jonsson, Magnus
    Linköping University, Department of Science and Technology, Laboratory of Organic Electronics. Linköping University, Faculty of Science & Engineering. Stellenbosch Univ, South Africa.
    Switchable Broadband Terahertz Absorbers Based on Conducting Polymer-Cellulose Aerogels2024In: Advanced Science, E-ISSN 2198-3844, Vol. 11, no 3, article id 2305898Article in journal (Refereed)
    Abstract [en]

    Terahertz (THz) technologies provide opportunities ranging from calibration targets for satellites and telescopes to communication devices and biomedical imaging systems. A main component will be broadband THz absorbers with switchability. However, optically switchable materials in THz are scarce and their modulation is mostly available at narrow bandwidths. Realizing materials with large and broadband modulation in absorption or transmission forms a critical challenge. This study demonstrates that conducting polymer-cellulose aerogels can provide modulation of broadband THz light with large modulation range from approximate to 13% to 91% absolute transmission, while maintaining specular reflection loss < -30 dB. The exceptional THz modulation is associated with the anomalous optical conductivity peak of conducting polymers, which enhances the absorption in its oxidized state. The study also demonstrates the possibility to reduce the surface hydrophilicity by simple chemical modifications, and shows that broadband absorption of the aerogels at optical frequencies enables de-frosting by solar-induced heating. These low-cost, aqueous solution-processable, sustainable, and bio-friendly aerogels may find use in next-generation intelligent THz devices.

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  • 8.
    Kuang, Chaoyang
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials. Linköping University, Faculty of Science & Engineering.
    Hu, Zhang-Jun
    Linköping University, Department of Physics, Chemistry and Biology, Molecular Surface Physics and Nano Science. Linköping University, Faculty of Science & Engineering.
    Yuan, Zhongcheng
    Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials. Linköping University, Faculty of Science & Engineering.
    Wen, Kaichuan
    Nanjing Tech Univ, Peoples R China; Nanjing Tech Univ, Peoples R China.
    Qing, Jian
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering. Jinan Univ, Peoples R China.
    Kobera, Libor
    Czech Acad Sci, Czech Republic.
    Abbrent, Sabina
    Czech Acad Sci, Czech Republic.
    Brus, Jiri
    Czech Acad Sci, Czech Republic.
    Yin, Chunyang
    Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials. Linköping University, Faculty of Science & Engineering.
    Wang, Heyong
    Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials. Linköping University, Faculty of Science & Engineering.
    Xu, Weidong
    Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials. Linköping University, Faculty of Science & Engineering.
    Wang, Jianpu
    Nanjing Tech Univ, Peoples R China; Nanjing Tech Univ, Peoples R China.
    Bai, Sai
    Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials. Linköping University, Faculty of Science & Engineering.
    Gao, Feng
    Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials. Linköping University, Faculty of Science & Engineering.
    Critical role of additive-induced molecular interaction on the operational stability of perovskite light-emitting diodes2021In: Joule, E-ISSN 2542-4351, Vol. 5, no 3, p. 618-630Article in journal (Refereed)
    Abstract [en]

    Despite rapid improvements in efficiency and brightness of perovskite light-emitting diodes (PeLEDs), the poor operational stability remains a critical challenge hindering their practical applications. Here, we demonstrate greatly improved operational stability of high-efficiency PeLEDs, enabled by incorporating dicarboxylic acids into the precursor for perovskite depositions. We reveal that the dicarboxylic acids efficiently eliminate reactive organic ingredients in perovskite emissive layers through an in situ amidation process, which is catalyzed by the alkaline zinc oxide substrate. The formed stable amides prohibit detrimental reactions between the perovskites and the charge injection layer underneath, stabilizing the perovskites and the interfacial contacts and ensuring the excellent operational stability of the resulting PeLEDs. Through rationally optimizing the amidation reaction in the perovskite emissive layers, we achieve efficient PeLEDs with a peak external quantum efficiency of 18.6% and a long half-life time of 682 h at 20 mA cm(-2), presenting an important breakthrough in PeLEDs.

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  • 9.
    Qing, Jian
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering. Shenzhen Univ, Peoples R China.
    Kuang, Chaoyang
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Wang, Heyong
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Wang, Yuming
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Liu, Xiaoke
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Bai, Sai
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Li, Mingjie
    Nanyang Technol Univ, Singapore.
    Sum, Tze Chien
    Nanyang Technol Univ, Singapore.
    Hu, Zhang-Jun
    Linköping University, Department of Physics, Chemistry and Biology, Molecular Surface Physics and Nano Science. Linköping University, Faculty of Science & Engineering.
    Zhang, Wenjing
    Shenzhen Univ, Peoples R China.
    Gao, Feng
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    High-Quality Ruddlesden-Popper Perovskite Films Based on In Situ Formed Organic Spacer Cations2019In: Advanced Materials, ISSN 0935-9648, E-ISSN 1521-4095, Vol. 31, no 41, article id 1904243Article in journal (Refereed)
    Abstract [en]

    Ruddlesden-Popper perovskites (RPPs), consisting of alternating organic spacer layers and inorganic layers, have emerged as a promising alternative to 3D perovskites for both photovoltaic and light-emitting applications. The organic spacer layers provide a wide range of new possibilities to tune the properties and even provide new functionalities for RPPs. However, the preparation of state-of-the-art RPPs requires organic ammonium halides as the starting materials, which need to be ex situ synthesized. A novel approach to prepare high-quality RPP films through in situ formation of organic spacer cations from amines is presented. Compared with control devices fabricated from organic ammonium halides, this new approach results in similar (and even better) device performance for both solar cells and light-emitting diodes. High-quality RPP films are fabricated based on different types of amines, demonstrating the universality of the approach. This approach not only represents a new pathway to fabricate efficient devices based on RPPs, but also provides an effective method to screen new organic spacers with further improved performance.

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  • 10.
    Qing, Jian
    et al.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, Faculty of Science & Engineering. Jinan Univ, Peoples R China; Shenzhen Univ, Peoples R China.
    Ramesh, Sankaran
    Nanyang Technol Univ, Singapore; Nanyang Technol Univ, Singapore.
    Liu, Xiaoke
    Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials. Linköping University, Faculty of Science & Engineering.
    Wang, Heyong
    Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials. Linköping University, Faculty of Science & Engineering.
    Yu, Hongling
    Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials. Linköping University, Faculty of Science & Engineering.
    Kuang, Chaoyang
    Linköping University, Department of Science and Technology, Laboratory of Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Hou, Lintao
    Jinan Univ, Peoples R China.
    Zhang, Wenjing
    Shenzhen Univ, Peoples R China.
    Sum, Tze Chien
    Nanyang Technol Univ, Singapore.
    Gao, Feng
    Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials. Linköping University, Faculty of Science & Engineering.
    Spacer cation engineering in Ruddlesden-Popper perovskites for efficient red light-emitting diodes with recommendation 2020 color coordinates2023In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 616, article id 156454Article in journal (Refereed)
    Abstract [en]

    Ruddlesden-Popper perovskites (RPPs) have been demonstrated as a very promising approach for tuning the emission color of perovskite light-emitting diodes (PeLEDs). However, achieving high-performance red PeLEDs with recommendation 2020 color coordinates is still challenging due to the lack of reasonable control over the properties of RPP films. Here, we demonstrate that the judicious selection of spacer cations in RPPs affords a lever for engineering their film properties, including phase distribution, energy funneling process, trap density, and carrier mobility. Four structurally related spacer cations, benzylammonium (BZA), phenylethylammonium (PEA), 3-phenyl-1-propylammonium (PPA), and phenoxyethylammonium (POEA), are studied. Owing to narrow phase distribution, efficient energy funneling, and low trap density, the POEA-based RPP films enable efficient red PeLEDs with a peak external quantum efficiency of 10.3%, a maximum brightness of 1052 cd m- 2, and excellent spectral stability. Significantly, the electroluminescence spectrum represents CIE 1931 color coordinates of (0.71, 0.29), which meets the recommendation 2020 standard (0.708, 0.292). The findings provide useful guidelines for the rational design of new organic spacer cations for RPPs with high performance.

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  • 11.
    Sun, Xiao
    et al.
    Univ Elect Sci & Technol China, Peoples R China.
    Chen, Shangzhi
    Linköping University, Department of Science and Technology, Laboratory of Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Kuang, Chaoyang
    Linköping University, Department of Science and Technology, Laboratory of Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Fu, Wenjie
    Univ Elect Sci & Technol China, Peoples R China.
    Li, Xuesong
    Univ Elect Sci & Technol China, Peoples R China; Univ Elect Sci & Technol China, Peoples R China; Univ Elect Sci & Technol China, Peoples R China.
    Duan, Zhaoyun
    Univ Elect Sci & Technol China, Peoples R China.
    Wen, Qiye
    Univ Elect Sci & Technol China, Peoples R China; Univ Elect Sci & Technol China, Peoples R China; Univ Elect Sci & Technol China, Peoples R China.
    Gradient-Reduced Graphene Oxide Aerogel with Ultrabroadband Absorption from Microwave to Terahertz Bands2023In: ACS Applied Nano Materials, E-ISSN 2574-0970Article in journal (Refereed)
    Abstract [en]

    Ultrabroadband electromagnetic (EM) absorbers, especially those covering microwave to terahertz (THz) bands, are urgently desired in multispectral applications such as 6G communication, radar stealth, atmospheric remote sensing, and radio astronomy. Here, we demonstrate that chemically reduced graphene oxide aerogels can be designed as an excellent absorber with the features of ultrabroadband, light weight, compressibility, and high-temperature resistance. This magnetic-free pyramidal absorber shows remarkably broad qualified absorption bandwidth from 4.7 GHz to 4 THz, with reflection loss < -20 dB in the microwave and < -40 dB in the THz band. Especially, an unprecedentedly excellent average absorption intensity of -53.9 dB (absorptivity over 99.999%) is obtained in the frequency range from 0.5 to 4 THz. We experimentally clarify that the gradient macrostructure together with the porous microstructure underlies the continuous impedance matching in such a large frequency range spanning about 3 orders of magnitude and leads to the consecutive strong EM absorption from microwave to terahertz. We believe that this absorber will offer multifunctional and multispectral applications in many scientific and technological fields.

  • 12.
    Wang, Heyong
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials. Linköping University, Faculty of Science & Engineering.
    Chen, Zhan
    Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials. Linköping University, Faculty of Science & Engineering. Jinan Univ, Peoples R China.
    Hu, Jingcong
    Beijing Univ Technol, Peoples R China.
    Yu, Hongling
    Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials. Linköping University, Faculty of Science & Engineering.
    Kuang, Chaoyang
    Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials. Linköping University, Faculty of Science & Engineering.
    Qin, Jiajun
    Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials. Linköping University, Faculty of Science & Engineering.
    Liu, Xianjie
    Linköping University, Department of Science and Technology, Laboratory of Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Lu, Yue
    Beijing Univ Technol, Peoples R China.
    Fahlman, Mats
    Linköping University, Department of Science and Technology, Laboratory of Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Hou, Lintao
    Jinan Univ, Peoples R China.
    Liu, Xiaoke
    Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials. Linköping University, Faculty of Science & Engineering.
    Gao, Feng
    Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials. Linköping University, Faculty of Science & Engineering.
    Dynamic Redistribution of Mobile Ions in Perovskite Light-Emitting Diodes2021In: Advanced Functional Materials, ISSN 1616-301X, E-ISSN 1616-3028, Vol. 31, no 8, article id 2007596Article in journal (Refereed)
    Abstract [en]

    Despite quick development of perovskite light-emitting diodes (PeLEDs) during the past few years, the fundamental mechanisms on how ion migration affects device efficiency and stability remain unclear. Here, it is demonstrated that the dynamic redistribution of mobile ions in the emissive layer plays a key role in the performance of PeLEDs and can explain a range of abnormal behaviours commonly observed during the device measurement. The dynamic redistribution of mobile ions changes charge-carrier injection and leads to increased recombination current; at the same time, the ion redistribution also changes charge transport and results in decreased shunt resistance current. As a result, the PeLEDs show hysteresis in external quantum efficiencies (EQEs) and radiance, that is, higher EQEs and radiance during the reverse voltage scan than during the forward scan. In addition, the changes on charge injection and transport induced by the ion redistribution also well explain the rise of the EQE/radiance values under constant driving voltages. The argument is further rationalized by adding extra formamidinium iodide (FAI) into optimized PeLEDs based on FAPbI(3), resulting in more significant hysteresis and shorter operational stability of the PeLEDs.

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  • 13.
    Yi, Chang
    et al.
    Nanjing Tech Univ NanjingTech, Peoples R China.
    Liu, Chao
    Nanjing Tech Univ NanjingTech, Peoples R China.
    Wen, Kaichuan
    Nanjing Tech Univ NanjingTech, Peoples R China.
    Liu, Xiaoke
    Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials. Linköping University, Faculty of Science & Engineering.
    Zhang, Hao
    Nanjing Tech Univ NanjingTech, Peoples R China.
    Yu, Yong
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, Faculty of Science & Engineering.
    Fan, Ning
    Nanjing Tech Univ NanjingTech, Peoples R China.
    Ji, Fuxiang
    Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials. Linköping University, Faculty of Science & Engineering.
    Kuang, Chaoyang
    Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials. Linköping University, Faculty of Science & Engineering.
    Ma, Bo
    Nanjing Tech Univ NanjingTech, Peoples R China.
    Tu, Cailing
    Nanjing Tech Univ NanjingTech, Peoples R China.
    Zhang, Ya
    Nanjing Tech Univ NanjingTech, Peoples R China.
    Xue, Chen
    Northwestern Polytech Univ, Peoples R China.
    Li, Renzhi
    Nanjing Tech Univ NanjingTech, Peoples R China.
    Gao, Feng
    Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials. Linköping University, Faculty of Science & Engineering.
    Huang, Wei
    Nanjing Tech Univ NanjingTech, Peoples R China; Northwestern Polytech Univ, Peoples R China.
    Wang, Jianpu
    Nanjing Tech Univ NanjingTech, Peoples R China.
    Intermediate-phase-assisted low-temperature formation of gamma-CsPbI3 films for high-efficiency deep-red light-emitting devices2020In: Nature Communications, E-ISSN 2041-1723, Vol. 11, no 1, article id 4736Article in journal (Refereed)
    Abstract [en]

    Black phase CsPbI3 is attractive for optoelectronic devices, while usually it has a high formation energy and requires an annealing temperature of above 300 degrees C. The formation energy can be significantly reduced by adding HI in the precursor. However, the resulting films are not suitable for light-emitting applications due to the high trap densities and low photoluminescence quantum efficiencies, and the low temperature formation mechanism is not well understood yet. Here, we demonstrate a general approach for deposition of gamma -CsPbI3 films at 100 degrees C with high photoluminescence quantum efficiencies by adding organic ammonium cations, and the resulting light-emitting diode exhibits an external quantum efficiency of 10.4% with suppressed efficiency roll-off. We reveal that the low-temperature crystallization process is due to the formation of low-dimensional intermediate states, and followed by interionic exchange. This work provides perspectives to tune phase transition pathway at low temperature for CsPbI3 device applications. Exploiting low-temperature formed black phase CsPbI3 for light-emitting applications remains a challenge. Here, the authors propose a method to enable the deposition of gamma -CsPbI3 films at 100C and demonstrate a light-emitting diode with an external quantum efficiency of 10.4% with suppressed efficiency roll-off.

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  • 14.
    Yu, Yong
    et al.
    Linköping University, Department of Science and Technology, Laboratory of Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Wang, Heyong
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Xu, Weidong
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Kuang, Chaoyang
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Ji, Fuxiang
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Braun, Slawomir
    Linköping University, Department of Science and Technology, Laboratory of Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Liu, Xianjie
    Linköping University, Department of Science and Technology, Laboratory of Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Yi, Chang
    Nanjing Tech Univ NanjingTech, Peoples R China.
    Gao, Feng
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Fahlman, Mats
    Linköping University, Department of Science and Technology, Laboratory of Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Dimensional Tailoring of Ultrahigh Vacuum Annealing-Assisted Quantum Wells for the Efficiency Enhancement of Perovskite Light-Emitting Diodes2020In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 12, no 22, p. 24965-24970Article in journal (Refereed)
    Abstract [en]

    Quasi-two-dimensional (Q-2D) perovskites featured with multidimensional quantum wells (QWs) have been the main candidates for optoelectronic applications. However, excessive low-dimensional perovskites are unfavorable to the device efficiency due to the phonon-exciton interaction and the inclusion of insulating large organic cations. Herein, the formation of low-dimensional QWs is suppressed by removing the organic cation 1-naphthylmethylamine iodide (NMAI) through ultrahigh vacuum (UHV) annealing. Perovskite light-emitting diode (PLED) devices based on films annealed with optimized UHV conditions show a higher external quantum efficiency (EQE) of 13.0% and wall-plug efficiency of 11.1% compared to otherwise identical devices with films annealed in a glovebox.

  • 15.
    Yuan, Zhongcheng
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials. Linköping University, Faculty of Science & Engineering.
    Hu, Zhang-Jun
    Linköping University, Department of Physics, Chemistry and Biology, Molecular Surface Physics and Nano Science. Linköping University, Faculty of Science & Engineering.
    Persson, Ingemar
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Wang, Chuan Fei
    Linköping University, Department of Science and Technology, Laboratory of Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Liu, Xianjie
    Linköping University, Department of Science and Technology, Laboratory of Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Kuang, Chaoyang
    Linköping University, Department of Science and Technology, Laboratory of Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Xu, Weidong
    Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials. Linköping University, Faculty of Science & Engineering.
    Bai, Sai
    Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials. Linköping University, Faculty of Science & Engineering. Univ Elect Sci & Technol China, Peoples R China.
    Gao, Feng
    Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials. Linköping University, Faculty of Science & Engineering.
    Interface-assisted cation exchange enables high-performance perovskiteLEDs with tunable near-infrared emissions2022In: Joule, E-ISSN 2542-4351, Vol. 6, no 10, p. 2423-2436Article in journal (Refereed)
    Abstract [en]

    Achieving high-quality cesium-formamidinium lead iodide (CsxFA1_xPbI3) perovskites with tunable band gaps is highly desired for optoelectronic applications including solar cells and light -emit-ting diodes (LEDs). Herein, by utilizing an alkaline-interface-assisted cation-exchange method, we fabricate highly emissive CsxFA1_x PbI3 perovskite films with fine-tunable Cs-FA alloying ratio for emis-sion-tunable near-infrared (NIR) LEDs. We reveal that the deproto-nation of FA+ cations and the formation of hydrogen-bonded gels consisting of CsI and FA facilitated by the zinc oxide underneath effectively removes the Cs-FA ion-exchange barrier, promoting the formation of phase-pure CsxFA1_xPbI3 films with tunable emis-sions filling the gap between that of pure Cs-and FA-based perov-skites. The obtained NIR perovskite LEDs (PeLEDs) peaking from 715 to 780 nm simultaneously demonstrate high peak external quantum efficiencies of over 15%, maximum radiances exceeding 300 W sr_1 m_2, and high power conversion efficiencies above 10% at 100 mA cm_2, representing the best-performing LEDs based on solution-processed NIR emitters in a similar region.

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  • 16.
    Yuan, Zhongcheng
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Miao, Yanfeng
    Nanjing Tech Univ, Peoples R China.
    Hu, Zhang-Jun
    Linköping University, Department of Physics, Chemistry and Biology, Molecular Surface Physics and Nano Science. Linköping University, Faculty of Science & Engineering.
    Xu, Weidong
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering. Nanjing Tech Univ, Peoples R China.
    Kuang, Chaoyang
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Pan, Kang
    Nanjing Tech Univ, Peoples R China.
    Liu, Pinlei
    Nanjing Tech Univ, Peoples R China.
    Lai, Jingya
    Nanjing Tech Univ, Peoples R China.
    Sun, Baoquan
    Soochow Univ, Peoples R China.
    Wang, Jianpu
    Nanjing Tech Univ, Peoples R China.
    Bai, Sai
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Gao, Feng
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Unveiling the synergistic effect of precursor stoichiometry and interfacial reactions for perovskite light-emitting diodes2019In: Nature Communications, E-ISSN 2041-1723, Vol. 10, article id 2818Article in journal (Refereed)
    Abstract [en]

    Metal halide perovskites are emerging as promising semiconductors for cost-effective and high-performance light-emitting diodes (LEDs). Previous investigations have focused on the optimisation of the emissive perovskite layer, for example, through quantum confinement to enhance the radiative recombination or through defect passivation to decrease non-radiative recombination. However, an in-depth understanding of how the buried charge transport layers affect the perovskite crystallisation, though of critical importance, is currently missing for perovskite LEDs. Here, we reveal synergistic effect of precursor stoichiometry and interfacial reactions for perovskite LEDs, and establish useful guidelines for rational device optimization. We reveal that efficient deprotonation of the undesirable organic cations by a metal oxide interlayer with a high isoelectric point is critical to promote the transition of intermediate phases to highly emissive perovskite films. Combining our findings with effective defect passivation of the active layer, we achieve high-efficiency perovskite LEDs with a maximum external quantum efficiency of 19.6%.

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  • 17.
    Zhao, Haifeng
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering. Univ Elect Sci & Technol China, Peoples R China.
    Chen, Hongting
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering. Jinan Univ, Peoples R China.
    Bai, Sai
    Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials. Linköping University, Faculty of Science & Engineering. Zhejiang Univ, Peoples R China.
    Kuang, Chaoyang
    Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials. Linköping University, Faculty of Science & Engineering.
    Luo, Xiyu
    Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials. Linköping University, Faculty of Science & Engineering. Tsinghua Univ, Peoples R China.
    Teng, Pengpeng
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering. Nanjing Univ Aeronaut & Astronaut, Peoples R China.
    Yin, Chunyang
    Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials. Linköping University, Faculty of Science & Engineering.
    Zeng, Peng
    Univ Elect Sci & Technol China, Peoples R China.
    Hou, Lintao
    Jinan Univ, Peoples R China.
    Yang, Ying
    Nanjing Univ Aeronaut & Astronaut, Peoples R China.
    Duan, Lian
    Tsinghua Univ, Peoples R China.
    Gao, Feng
    Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials. Linköping University, Faculty of Science & Engineering.
    Liu, Mingzhen
    Univ Elect Sci & Technol China, Peoples R China.
    High-Brightness Perovskite Light-Emitting Diodes Based on FAPbBr(3) Nanocrystals with Rationally Designed Aromatic Ligands2021In: ACS Energy Letters, E-ISSN 2380-8195, Vol. 6, no 7, p. 2395-2403Article in journal (Refereed)
    Abstract [en]

    Despite rapid developments of light-emitting diodes (LEDs) based on emerging perovskite nanocrystals (PeNCs), it remains challenging to achieve devices with integrated high efficiencies and high brightness because of the insulating long-chain ligands used for the PeNCs. Herein, we develop highly luminescent and stable formamidinium lead bromide PeNCs capped with rationally designed short aromatic ligands of 2-naphthalenesulfonic acid (NSA) for LEDs. Compared with commonly used oleic acid ligands, the NSA molecules not only preserve the surface properties of the PeNCs during the purification but also notably improve the electrical properties of the assembled emissive layers, ensuring efficient charge injection/transport in the devices. The resulting champion LED with electroluminescence approaching the Rec. 2020 green primary color demonstrates a high brightness of 67 115 cd cm(-2) and a peak external quantum efficiency of 19.2%. More impressively, the device shows negligibly decreased efficiency at an elevated brightness of 20 000 cd cm(-2) and a well-retained efficiency of over 10% at around 65 000 cd cm(-2), presenting a breakthrough in LEDs based on PeNCs.

  • 18.
    Zhao, Haifeng
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering. Univ Elect Sci & Technol China, Peoples R China; Univ Elect Sci & Technol China, Peoples R China.
    Hu, Zhang-Jun
    Linköping University, Department of Physics, Chemistry and Biology, Molecular Surface Physics and Nano Science. Linköping University, Faculty of Science & Engineering.
    Wei, Linfeng
    Univ Elect Sci & Technol China, Peoples R China; Univ Elect Sci & Technol China, Peoples R China.
    Zeng, Peng
    Univ Elect Sci & Technol China, Peoples R China; Univ Elect Sci & Technol China, Peoples R China.
    Kuang, Chaoyang
    Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials. Linköping University, Faculty of Science & Engineering.
    Liu, Xiaochun
    Univ Elect Sci & Technol China, Peoples R China; Univ Elect Sci & Technol China, Peoples R China.
    Bai, Sai
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Gao, Feng
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Liu, Mingzhen
    Univ Elect Sci & Technol China, Peoples R China; Univ Elect Sci & Technol China, Peoples R China.
    Efficient and High-Luminance Perovskite Light-Emitting Diodes Based on CsPbBr3 Nanocrystals Synthesized from a Dual-Purpose Organic Lead SourceIn: Small, ISSN 1613-6810, E-ISSN 1613-6829, article id 2003939Article in journal (Refereed)
    Abstract [en]

    Rational engineering of the surface properties of perovskite nanocrystals (PeNCs) is critical to obtain light emitters with simultaneous high photoluminescence efficiency and excellent charge transport properties for light-emitting diodes (LEDs). However, the commonly used lead halide sources make it hard to rationally optimize the surface compositions of the PeNCs. In addition, previously developed ligand engineering strategies for conventional inorganic nanocrystals easily deteriorate surface properties of the PeNCs, bringing additional difficulties in optimizing their optoelectronic properties. In this work, a novel strategy of employing a dual-purpose organic lead source for the synthesis of highly luminescent PeNCs with enhanced charge transport property is developed. Lead naphthenate (Pb(NA)(2)), of which the metal ions work as lead sources while the naphthenate can function as the surface ligands afterward, is explored and the obtained products under different synthesis conditions are comprehensively investigated. Monodispersed cesium lead bromide (CsPbBr3) with controllable size and excellent optical properties, showing superior photoluminescence quantum yields up to 80%, is obtained. Based on the simultaneously enhanced electrical properties of the Pb(NA)(2)-derived PeNCs, the resultant LEDs demonstrate a high peak external quantum efficiency of 8.44% and a superior maximum luminance of 31 759 cd cm(-2).

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  • 19.
    Zou, Yatao
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering. Soochow Univ, Peoples R China.
    Teng, Pengpeng
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering. Nanjing Univ Aeronaut & Astronaut, Peoples R China.
    Xu, Weidong
    Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials. Linköping University, Faculty of Science & Engineering.
    Zheng, Guanhaojie
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Lin, Weihua
    Lund Univ, Sweden.
    Yin, Jun
    King Abdullah Univ Sci & Technol, Saudi Arabia.
    Kobera, Libor
    Czech Acad Sci, Czech Republic.
    Abbrent, Sabina
    Czech Acad Sci, Czech Republic.
    Li, Xiangchun
    Nanjing Univ Posts & Telecommun, Peoples R China.
    Steele, Julian A.
    Katholieke Univ Leuven, Belgium.
    Solano, Eduardo
    Alba Synchrotron Light Source, Spain.
    Roeffaers, Maarten B. J.
    Katholieke Univ Leuven, Belgium.
    Li, Jun
    Lund Univ, Sweden.
    Cai, Lei
    Soochow Univ, Peoples R China.
    Kuang, Chaoyang
    Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials. Linköping University, Faculty of Science & Engineering.
    Scheblykin, Ivan G.
    Lund Univ, Sweden.
    Brus, Jiri
    Czech Acad Sci, Czech Republic.
    Zheng, Kaibo
    Lund Univ, Sweden; Tech Univ Denmark, Denmark.
    Yang, Ying
    Nanjing Univ Aeronaut & Astronaut, Peoples R China.
    Mohammed, Omar F.
    King Abdullah Univ Sci & Technol, Saudi Arabia.
    Bakr, Osman M.
    King Abdullah Univ Sci & Technol, Saudi Arabia.
    Pullerits, Tönu
    Lund Univ, Sweden.
    Bai, Sai
    Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials. Linköping University, Faculty of Science & Engineering. Zhejiang Univ, Peoples R China.
    Sun, Baoquan
    Soochow Univ, Peoples R China.
    Gao, Feng
    Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials. Linköping University, Faculty of Science & Engineering.
    Manipulating crystallization dynamics through chelating molecules for bright perovskite emitters2021In: Nature Communications, E-ISSN 2041-1723, Vol. 12, no 1, article id 4831Article in journal (Refereed)
    Abstract [en]

    Multidentate molecular additives are widely used to passivate perovskite, yet the role of chelate effect is still unclear. Here, the authors investigate a wide range of additives with different coordination number and functional moieties to establish correlation between coordination affinity and perovskite crystallisation dynamics. Molecular additives are widely utilized to minimize non-radiative recombination in metal halide perovskite emitters due to their passivation effects from chemical bonds with ionic defects. However, a general and puzzling observation that can hardly be rationalized by passivation alone is that most of the molecular additives enabling high-efficiency perovskite light-emitting diodes (PeLEDs) are chelating (multidentate) molecules, while their respective monodentate counterparts receive limited attention. Here, we reveal the largely ignored yet critical role of the chelate effect on governing crystallization dynamics of perovskite emitters and mitigating trap-mediated non-radiative losses. Specifically, we discover that the chelate effect enhances lead-additive coordination affinity, enabling the formation of thermodynamically stable intermediate phases and inhibiting halide coordination-driven perovskite nucleation. The retarded perovskite nucleation and crystal growth are key to high crystal quality and thus efficient electroluminescence. Our work elucidates the full effects of molecular additives on PeLEDs by uncovering the chelate effect as an important feature within perovskite crystallization. As such, we open new prospects for the rationalized screening of highly effective molecular additives.

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