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Diesing S, Zhang L, Zysman-Colman E, Samuel IDW. A figure of merit for efficiency roll-off in TADF-based organic LEDs. Nature 2024; 627:747-753. [PMID: 38538942 PMCID: PMC10972759 DOI: 10.1038/s41586-024-07149-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2023] [Accepted: 02/01/2024] [Indexed: 04/01/2024]
Abstract
Organic light-emitting diodes (OLEDs) are a revolutionary light-emitting display technology that has been successfully commercialized in mobile phones and televisions1,2. The injected charges form both singlet and triplet excitons, and for high efficiency it is important to enable triplets as well as singlets to emit light. At present, materials that harvest triplets by thermally activated delayed fluorescence (TADF) are a very active field of research as an alternative to phosphorescent emitters that usually use heavy metal atoms3,4. Although excellent progress has been made, in most TADF OLEDs there is a severe decrease of efficiency as the drive current is increased, known as efficiency roll-off. So far, much of the literature suggests that efficiency roll-off should be reduced by minimizing the energy difference between singlet and triplet excited states (ΔEST) to maximize the rate of conversion of triplets to singlets by means of reverse intersystem crossing (kRISC)5-20. We analyse the efficiency roll-off in a wide range of TADF OLEDs and find that neither of these parameters fully accounts for the reported efficiency roll-off. By considering the dynamic equilibrium between singlets and triplets in TADF materials, we propose a figure of merit for materials design to reduce efficiency roll-off and discuss its correlation with reported data of TADF OLEDs. Our new figure of merit will guide the design and development of TADF materials that can reduce efficiency roll-off. It will help improve the efficiency of TADF OLEDs at realistic display operating conditions and expand the use of TADF materials to applications that require high brightness, such as lighting, augmented reality and lasing.
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Affiliation(s)
- S Diesing
- Organic Semiconductor Centre, SUPA, School of Physics and Astronomy, University of St Andrews, St Andrews, UK
- Organic Semiconductor Centre, EaStCHEM, School of Chemistry, St Andrews, UK
| | - L Zhang
- Organic Semiconductor Centre, SUPA, School of Physics and Astronomy, University of St Andrews, St Andrews, UK
- Organic Semiconductor Centre, EaStCHEM, School of Chemistry, St Andrews, UK
| | - E Zysman-Colman
- Organic Semiconductor Centre, EaStCHEM, School of Chemistry, St Andrews, UK.
| | - I D W Samuel
- Organic Semiconductor Centre, SUPA, School of Physics and Astronomy, University of St Andrews, St Andrews, UK.
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2
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Zhang S, Lin C, Liu C, Du D. Enantioselective Synthesis of δ-Carbolinones via N-Heterocyclic Carbene Catalysis. J Org Chem 2022; 87:10441-10448. [PMID: 35819024 DOI: 10.1021/acs.joc.2c00952] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
An enantioselective synthesis of δ-carbolinones was accomplished through N-heterocyclic carbene-catalyzed formal [3+3] annulation of 3-aminoindoles with 2-bromoenals. This protocol offers a rapid and efficient synthetic approach for accessing a wide range of enantioenriched structurally interesting δ-carbolinones under mild reaction conditions.
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Affiliation(s)
- Simiao Zhang
- State Key Laboratory of Natural Medicines, School of Science, China Pharmaceutical University, Nanjing 210009, P. R. China
| | - Chen Lin
- State Key Laboratory of Natural Medicines, School of Science, China Pharmaceutical University, Nanjing 210009, P. R. China
| | - Chaolei Liu
- State Key Laboratory of Natural Medicines, School of Science, China Pharmaceutical University, Nanjing 210009, P. R. China
| | - Ding Du
- State Key Laboratory of Natural Medicines, School of Science, China Pharmaceutical University, Nanjing 210009, P. R. China
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Shao J, Chen C, Zhao W, Zhang E, Ma W, Sun Y, Chen P, Sheng R. Recent Advances of Interface Exciplex in Organic Light-Emitting Diodes. MICROMACHINES 2022; 13:298. [PMID: 35208422 PMCID: PMC8875368 DOI: 10.3390/mi13020298] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/22/2022] [Revised: 02/05/2022] [Accepted: 02/07/2022] [Indexed: 02/06/2023]
Abstract
The interface exciplex system is a promising technology for reaching organic light-emitting diodes (OLEDs) with low turn-on voltages, high efficiencies and long lifetimes due to its unique virtue of barrier-free charge transport, well-confined recombination region, and thermally activated delayed fluorescence characteristics. In this review, we firstly illustrate the mechanism frameworks and superiorities of the interface exciplex system. We then summarize the primary applications of interface exciplex systems fabricated by doping and doping-free technologies. The operation mechanisms of these OLEDs are emphasized briefly. In addition, various novel strategies for further improving the performances of interface exciplex-based devices are demonstrated. We believe this review will give a promising perspective and attract researchers to further develop this technology in the future.
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Affiliation(s)
- Jianhua Shao
- Institute of Physics and Electronic Information, Yantai University, Yantai 264005, China; (J.S.); (C.C.); (W.Z.); (E.Z.); (W.M.); (Y.S.)
| | - Cong Chen
- Institute of Physics and Electronic Information, Yantai University, Yantai 264005, China; (J.S.); (C.C.); (W.Z.); (E.Z.); (W.M.); (Y.S.)
| | - Wencheng Zhao
- Institute of Physics and Electronic Information, Yantai University, Yantai 264005, China; (J.S.); (C.C.); (W.Z.); (E.Z.); (W.M.); (Y.S.)
| | - Erdong Zhang
- Institute of Physics and Electronic Information, Yantai University, Yantai 264005, China; (J.S.); (C.C.); (W.Z.); (E.Z.); (W.M.); (Y.S.)
| | - Wenjie Ma
- Institute of Physics and Electronic Information, Yantai University, Yantai 264005, China; (J.S.); (C.C.); (W.Z.); (E.Z.); (W.M.); (Y.S.)
| | - Yuanping Sun
- Institute of Physics and Electronic Information, Yantai University, Yantai 264005, China; (J.S.); (C.C.); (W.Z.); (E.Z.); (W.M.); (Y.S.)
| | - Ping Chen
- Institute of Physics and Electronic Information, Yantai University, Yantai 264005, China; (J.S.); (C.C.); (W.Z.); (E.Z.); (W.M.); (Y.S.)
- State Key Laboratory on Integrated Optoelectronics, College of Electronic Science and Engineering, Jilin University, Changchun 130012, China
| | - Ren Sheng
- Institute of Physics and Electronic Information, Yantai University, Yantai 264005, China; (J.S.); (C.C.); (W.Z.); (E.Z.); (W.M.); (Y.S.)
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Khammultri P, Chasing P, Chitpakdee C, Namuangruk S, Sudyoadsuk T, Promarak V. Red to orange thermally activated delayed fluorescence polymers based on 2-(4-(diphenylamino)-phenyl)-9 H-thioxanthen-9-one-10,10-dioxide for efficient solution-processed OLEDs. RSC Adv 2021; 11:24794-24806. [PMID: 35481012 PMCID: PMC9037026 DOI: 10.1039/d1ra04599g] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2021] [Accepted: 07/08/2021] [Indexed: 12/02/2022] Open
Abstract
Most highly efficient thermally activated delayed fluorescence (TADF)-based organic light-emitting diodes (OLEDs) are multi-layer devices fabricated by thermal vacuum evaporation techniques, which are unfavorable for real applications. However, there are only a few reported examples of efficient solution-processed TADF OLEDs, in particular TADF polymer OLEDs. Herein, a series of solution-processable TADF conjugated polymers (PCTXO/PCTXO-Fx (x = 25, 50 and 75)) were designed and synthesized by copolymerization of 2-(4-(diphenylamino)-phenyl)-9H-thioxanthen-9-one-10,10-dioxide (TXO-TPA) as a red/orange emissive TADF unit, 9,9'-((fluorene-9,9-diyl)-bis(octane-8,1-diyl))-bis(3,6-di-tert-butylcarbazole) as host/hole-transporting unit and 2,7-N-(heptadecan-9-yl)carbazole as a conjugated linker and solubilizing group. They possessed a conjugated backbone with donor TPA-carbazole/fluorene moieties and a pendent acceptor 9H-thioxanthen-9-one-10,10-dioxide (TXO) forming a twisted donor-acceptor structure. These polymers in neat films displayed red/orange color emissions (601-655 nm) with TADF properties, proved by theory calculations and transient PL decay measurements. Their hole-transporting capability was improved when the content of 9,9'-((fluorene-9,9-diyl)-bis(octane-8,1-diyl))-bis(3,6-di-tert-butylcarbazole) within the polymers increased. All polymers were successfully employed as emitters in solution-processed OLEDs. In particular, the doped OLED fabricated with PCTXO exhibited an intense deep orange emission at 603 nm with the best electroluminescence performance (a maximum external quantum efficiency 10.44%, a maximum current efficiency of 14.97 cd A-1 and a turn-on voltage of 4.2 V).
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Affiliation(s)
- Praetip Khammultri
- Department of Material Science and Engineering, School of Molecular Science & Engineering, Vidyasirimedhi Institute of Science and Technology Wangchan Rayong 21210 Thailand
| | - Pongsakorn Chasing
- Department of Material Science and Engineering, School of Molecular Science & Engineering, Vidyasirimedhi Institute of Science and Technology Wangchan Rayong 21210 Thailand
| | - Chirawat Chitpakdee
- National Nanotechnology Center (NANOTEC), National Science and Technology Development Agency Pathum Thani 12120 Thailand
| | - Supawadee Namuangruk
- National Nanotechnology Center (NANOTEC), National Science and Technology Development Agency Pathum Thani 12120 Thailand
| | - Taweesak Sudyoadsuk
- Department of Material Science and Engineering, School of Molecular Science & Engineering, Vidyasirimedhi Institute of Science and Technology Wangchan Rayong 21210 Thailand
| | - Vinich Promarak
- Department of Material Science and Engineering, School of Molecular Science & Engineering, Vidyasirimedhi Institute of Science and Technology Wangchan Rayong 21210 Thailand
- Research Network of NANOTEC-VISTEC on Nanotechnology for Energy, Vidyasirimedhi Institute of Science and Technology Wangchan Rayong 21210 Thailand
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Yu F, Sheng Y, Wu D, Qin K, Li H, Xie G, Xue Q, Sun Z, Lu Z, Ma H, Hang XC. Blue-Phosphorescent Pt(II) Complexes of Tetradentate Pyridyl–Carbolinyl Ligands: Synthesis, Structure, Photophysics, and Electroluminescence. Inorg Chem 2020; 59:14493-14500. [DOI: 10.1021/acs.inorgchem.0c02244] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Feiling Yu
- Key Laboratory of Flexible Electronics and Institute of Advanced Materials Nanjing Tech University, 30 South Puzhu Road, Nanjing 211816, China
| | - Yongjian Sheng
- Key Laboratory of Flexible Electronics and Institute of Advanced Materials Nanjing Tech University, 30 South Puzhu Road, Nanjing 211816, China
| | - Dandan Wu
- Key Laboratory of Flexible Electronics and Institute of Advanced Materials Nanjing Tech University, 30 South Puzhu Road, Nanjing 211816, China
| | - Ke Qin
- Key Laboratory of Flexible Electronics and Institute of Advanced Materials Nanjing Tech University, 30 South Puzhu Road, Nanjing 211816, China
| | - Hongbo Li
- Yanshan Branch of Beijing Research Institute of Chemical Industry, Sinopec, Beijing 102500, China
| | - Guohua Xie
- Sauvage Center for Molecular Sciences, Hubei Key Lab on Organic and Polymeric Optoelectronic Materials, Department of Chemistry, Wuhan University, Wuhan 430072, China
| | - Qin Xue
- Department of Physical Science and Technology, Central China Normal University, Wuhan 430079, China
| | - Zhengyi Sun
- Key Laboratory of Flexible Electronics and Institute of Advanced Materials Nanjing Tech University, 30 South Puzhu Road, Nanjing 211816, China
| | - Zhenzhong Lu
- Key Laboratory of Flexible Electronics and Institute of Advanced Materials Nanjing Tech University, 30 South Puzhu Road, Nanjing 211816, China
| | - Huili Ma
- Key Laboratory of Flexible Electronics and Institute of Advanced Materials Nanjing Tech University, 30 South Puzhu Road, Nanjing 211816, China
| | - Xiao-Chun Hang
- Key Laboratory of Flexible Electronics and Institute of Advanced Materials Nanjing Tech University, 30 South Puzhu Road, Nanjing 211816, China
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Dou D, Wu P, Liao Z, Hao J, Zhang J, Wang Z. A thermally activated delayed fluorescence exciplex to achieve highly efficient and stable blue and green phosphorescent organic light-emitting diodes. RSC Adv 2019; 9:23810-23817. [PMID: 35530600 PMCID: PMC9069484 DOI: 10.1039/c9ra02875g] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2019] [Accepted: 06/22/2019] [Indexed: 12/26/2022] Open
Abstract
The development of a thermally activated delayed fluorescence (TADF) exciplex with high energy is of great significance in achieving highly efficient blue, green, and red organic light-emitting diodes (OLEDs) for use in full-color displays and white lighting. Highly efficient and stable blue and green phosphorescent OLEDs were demonstrated by employing a TADF exciplex (energy: 2.9 eV) based on 4-substituted aza-9,9'-spirobifluorenes (aza-SBFs). Blue PhOLEDs demonstrated a maximum current efficiency (CE) of 47.9 cd A-1 and an external quantum efficiency (EQE) of 22.5% at 1300 cd m-2 (2.5 times the values of aza-SBF-based systems), with the best blue PhOLED demonstrating a CE, power efficiency (PE) and EQE of 60.3 cd A-1, 52.7 lm W-1, and 26.2%, respectively. Green PhOLEDs exhibited a CE of 78.1 cd A-1 and EQE of 22.5% at 9360 cd m-2, with the best green PhOLED exhibiting a maximum CE, PE, and EQE of 87.4 cd A-1, 101.6 lm W-1, and 24.5%, respectively. The device operational lifetime was improved over 17-fold compared to reference devices because of the high thermal stability of the materials and full utilization of the TADF exciplex energy, indicating their potential for application in commercial OLEDs.
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Affiliation(s)
- Dehai Dou
- Key Laboratory of Advanced Display and System Applications, Ministry of Education, Shanghai University 149 Yanchang Rd 200072 P. R. China +86-21-56333362 +86-21-56333362
- Department of Chemistry, Shanghai University 149 Yanchang Rd 200072 P. R. China
| | - Peng Wu
- Key Laboratory of Advanced Display and System Applications, Ministry of Education, Shanghai University 149 Yanchang Rd 200072 P. R. China +86-21-56333362 +86-21-56333362
- Department of Chemistry, Shanghai University 149 Yanchang Rd 200072 P. R. China
| | - Zhangcheng Liao
- Key Laboratory of Advanced Display and System Applications, Ministry of Education, Shanghai University 149 Yanchang Rd 200072 P. R. China +86-21-56333362 +86-21-56333362
- Department of Chemistry, Shanghai University 149 Yanchang Rd 200072 P. R. China
| | - Jian Hao
- Department of Chemistry, Shanghai University 149 Yanchang Rd 200072 P. R. China
| | - Jianhua Zhang
- Key Laboratory of Advanced Display and System Applications, Ministry of Education, Shanghai University 149 Yanchang Rd 200072 P. R. China +86-21-56333362 +86-21-56333362
| | - Zixing Wang
- Key Laboratory of Advanced Display and System Applications, Ministry of Education, Shanghai University 149 Yanchang Rd 200072 P. R. China +86-21-56333362 +86-21-56333362
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7
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Modern methods for the synthesis of δ-carbolines. Russ Chem Bull 2019. [DOI: 10.1007/s11172-019-2475-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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8
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Tao P, Miao Y, Wang H, Xu B, Zhao Q. High-Performance Organic Electroluminescence: Design from Organic Light-Emitting Materials to Devices. CHEM REC 2018; 19:1531-1561. [PMID: 30358067 DOI: 10.1002/tcr.201800139] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2018] [Accepted: 10/02/2018] [Indexed: 12/24/2022]
Abstract
Organic electroluminescence is considered as the most competitive alternative for the future solid-state displays and lighting techniques owing to many advantages such as self-luminescence, high efficiency, high contrast, high color rendering index, ultra-thin thickness, transparency, flat and flexibility, etc. The development of high-performance organic electroluminescence has become the continuing focus of research. In this personal account, a brief overview of representative achievements in our study on the design of highly efficient novel organic light-emitting materials (including fluorescent materials, phosphorescent iridium(III) complexes and conjugated polymers bearing phosphorescent iridium(III) complex) and high-performance device structures together with working principles are given. At last, we will give some perspectives on this fascinating field, and also try to provide some potential directions of research on the basis of the current stage of organic electroluminescence.
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Affiliation(s)
- Peng Tao
- Key Laboratory of Interface Science and Engineering in Advanced Materials of Ministry of Education and Research Center of Advanced Materials Science and Technology, Taiyuan University of Technology, No. 79, Yingze West Street, Taiyuan, 030024, P.R. China.,Key Laboratory for Organic Electronics and Information Displays and Institute of Advanced Materials (IAM), Jiangsu National Synergetic Innovation Center for Advanced Materials (SICAM), Nanjing University of Posts and Telecommunications (NUPT), No. 9, Wenyuan Road, Nanjing, 210023, P.R. China
| | - Yanqin Miao
- Key Laboratory of Interface Science and Engineering in Advanced Materials of Ministry of Education and Research Center of Advanced Materials Science and Technology, Taiyuan University of Technology, No. 79, Yingze West Street, Taiyuan, 030024, P.R. China
| | - Hua Wang
- Key Laboratory of Interface Science and Engineering in Advanced Materials of Ministry of Education and Research Center of Advanced Materials Science and Technology, Taiyuan University of Technology, No. 79, Yingze West Street, Taiyuan, 030024, P.R. China
| | - Bingshe Xu
- Key Laboratory of Interface Science and Engineering in Advanced Materials of Ministry of Education and Research Center of Advanced Materials Science and Technology, Taiyuan University of Technology, No. 79, Yingze West Street, Taiyuan, 030024, P.R. China
| | - Qiang Zhao
- Key Laboratory for Organic Electronics and Information Displays and Institute of Advanced Materials (IAM), Jiangsu National Synergetic Innovation Center for Advanced Materials (SICAM), Nanjing University of Posts and Telecommunications (NUPT), No. 9, Wenyuan Road, Nanjing, 210023, P.R. China
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Sarma M, Wong KT. Exciplex: An Intermolecular Charge-Transfer Approach for TADF. ACS APPLIED MATERIALS & INTERFACES 2018; 10:19279-19304. [PMID: 29613766 DOI: 10.1021/acsami.7b18318] [Citation(s) in RCA: 116] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Organic materials that display thermally activated delayed fluorescence (TADF) are a striking class of functional materials that have witnessed a booming progress in recent years. In addition to pure TADF emitters achieved by the subtle manipulations of intramolecular charge transfer processes with sophisticated molecular structures, a new class of efficient TADF-based OLEDs with emitting layer formed by blending electron donor and acceptor molecules that involve intermolecular charge transfer have also been fabricated. In contrast to pure TADF materials, the exciplex-based systems can realize small Δ EST (0-0.05 eV) much more easily since the electron and hole are positioned on two different molecules, thereby giving small exchange energy. Consequently, exciplex-based OLEDs have the prospective to maximize the TADF contribution and achieve theoretical 100% internal quantum efficiency. Therefore, the challenging issue of achieving small Δ EST in organic systems could be solved. In this article, we summarize and discuss the latest and most significant developments regarding these rapidly evolving functional materials, wherein the majority of the reported exciplex forming systems are categorized into two subgroups, viz. (a) exciplex as TADF emitters and (b) those as hosts for fluorescent, phosphorescent and TADF dopants according to their structural features and applications. The working mechanisms of the direct electroluminescence from the donor/acceptor interface and the exciplex-forming systems as cohost for the realization of high efficiency OLEDs are reviewed and discussed. This article delivers a summary of the current progresses and achievements of exciplex-based researches and points out the future challenges to trigger more research endeavors to this growing field.
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Affiliation(s)
- Monima Sarma
- Department of Chemistry , National Taiwan University , Taipei 10617 , Taiwan
| | - Ken-Tsung Wong
- Department of Chemistry , National Taiwan University , Taipei 10617 , Taiwan
- Institute of Atomic and Molecular Science , Academia Sinica , Taipei 10617 , Taiwan
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Thermally Activated Delayed Fluorescence Emitters for Deep Blue Organic Light Emitting Diodes: A Review of Recent Advances. APPLIED SCIENCES-BASEL 2018. [DOI: 10.3390/app8040494] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
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