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Abstract
Near ultraviolet (NUV) light-emitting materials and devices are significant due to unique applications in anti-counterfeit, manufacturing industries, and hygienic treatments. However, the development of high-efficiency NUV electroluminescent devices encounters great challenges and is far behind their RGB emitter counterparts. Besides the photoluminescence quantum yields (PLQYs) of NUV materials being higher than 40%, charge injection and lopsided carrier transport also determine the device performance, leading to great efforts in optimizing the frontier molecular orbitals to fit the adjacent function layer. In the exploration of NUV materials, organic molecules are one of the primary candidates, given their preparative facility and structural variability. Recently, all-inorganic quantum-dot light-emitting diodes (QLEDs) of Cd-based, ZnSe, graphene and inorganic perovskite emitters and organic-inorganic hybrid lead halide perovskite nanocrystals (NCs) were demonstrated for achieving NUV electroluminescence. Owing to the great efforts devoted to NUV material engineering and device configuration, NUV materials and devices have achieved great advances over the last two decades. In this review, we retrospect the development of NUV materials and devices covering all promising systems, which may inspire the enthusiasm of researchers to explore the huge potential in the NUV region.
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Affiliation(s)
- Shuo Chen
- Key Laboratory of Functional Inorganic Material Chemistry, Ministry of Education, School of Chemistry and Materials, Heilongjiang University, 74 Xuefu Road, Harbin 150080, P. R. China.
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Yang S, Cao C, Islam A, Sun S, Deng Z, Li J, Ni S, Tong QX, Li MD. Disentangling Multiple Effects on Excited-State Intramolecular Charge Transfer among Asymmetrical Tripartite PPI-TPA/PCz Triads. Chemistry 2021; 27:1337-1345. [PMID: 32776379 DOI: 10.1002/chem.202002862] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2020] [Revised: 07/25/2020] [Indexed: 11/07/2022]
Abstract
By utilizing the bipolarity of 1,2-diphenylphenanthroimidazole (PPI), two types of asymmetrical tripartite triads (PPI-TPA and PPI-PCz) were designed with triphenylamine (TPA) and 9-phenylcarbazole (PCz). These triads are deep-blue luminescent materials with a high fluorescence quantum yield of nearly 100 %. To trace the photophysical behaviors of these triads, their excited-state evolution channels and interchromophoric interactions were investigated by ultrafast time-resolved transient absorption and excited-state theoretical calculations. The results suggest that the electronic nature, asymmetrical tripartite structure, and electron-hole distance of these triads, as well as solvent polarity, determine the lifetime of intramolecular charge transfer (ICT). Interestingly, PPI-PCz triads show anti-Kasha ICT, and the charge-transfer direction among the triads is adjustable. For the PPI-TPA triad, the electron is transferred from TPA to PPI, whereas for the PPI-PCz triad the electron is pushed from PPI to PCz. Exploration of the excited-state ICT in these triads may pave the way to design better luminescent materials in the future.
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Affiliation(s)
- Sirui Yang
- Department of Chemistry and Key Laboratory for Preparation and Application of Ordered Structure Materials of Guangdong Providence, Shantou University, Shantou, 515063, P. R. China
| | - Chen Cao
- Department of Chemistry and Key Laboratory for Preparation and Application of Ordered Structure Materials of Guangdong Providence, Shantou University, Shantou, 515063, P. R. China.,Center of Super-Diamond and Advanced Films (COSDAF), Department of Chemistry, City University of Hong Kong, Hong Kong SAR, 999077, P. R. China
| | - Amjad Islam
- Department of Chemistry and Key Laboratory for Preparation and Application of Ordered Structure Materials of Guangdong Providence, Shantou University, Shantou, 515063, P. R. China
| | - Shanshan Sun
- Department of Chemistry and Key Laboratory for Preparation and Application of Ordered Structure Materials of Guangdong Providence, Shantou University, Shantou, 515063, P. R. China
| | - Ziqi Deng
- Department of Chemistry and Key Laboratory for Preparation and Application of Ordered Structure Materials of Guangdong Providence, Shantou University, Shantou, 515063, P. R. China
| | - Jiayu Li
- Department of Chemistry and Key Laboratory for Preparation and Application of Ordered Structure Materials of Guangdong Providence, Shantou University, Shantou, 515063, P. R. China
| | - Shaofei Ni
- Department of Chemistry and Key Laboratory for Preparation and Application of Ordered Structure Materials of Guangdong Providence, Shantou University, Shantou, 515063, P. R. China
| | - Qing-Xiao Tong
- Department of Chemistry and Key Laboratory for Preparation and Application of Ordered Structure Materials of Guangdong Providence, Shantou University, Shantou, 515063, P. R. China
| | - Ming-De Li
- Department of Chemistry and Key Laboratory for Preparation and Application of Ordered Structure Materials of Guangdong Providence, Shantou University, Shantou, 515063, P. R. China
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Konidena RK, Lee KH, Lee JY, Hong WP. Triggering Thermally Activated Delayed Fluorescence by Managing the Heteroatom in Donor Scaffolds: Intriguing Photophysical and Electroluminescence Properties. Chem Asian J 2019; 14:2251-2258. [PMID: 30969458 DOI: 10.1002/asia.201900388] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2019] [Revised: 04/09/2019] [Indexed: 02/06/2023]
Abstract
Establishment of the structure-property relationships of thermally activated delayed fluorescence (TADF) materials has become a significant quest for the scientific community. Herein, two new donors, 10H-benzofuro[3,2-b]indole (BFI) and 10H-benzo[4,5]thieno[3,2-b]indole (BTI), have been developed and integrated with a aryltriazine acceptor to design the green TADF emitters benzofuro[3,2-b]indol-10-yl)-5-(4,6-diphenyl-1,3,5-triazin-2-yl)benzonitrile (BFICNTrz) and 2-(10H-benzo[4,5]thieno[3,2-b]indol-10-yl)-5-(4,6-diphenyl-1,3,5-triazin-2-yl)benzonitrile (BTICNTrz), respectively. The physicochemical and electroluminescence properties of the compounds were tuned by exchanging the heteroatom in the donor scaffold. Intriguingly, the electronegativity of the heteroatom and the ionization potential of the donor unit played vital roles in control of the singlet-triplet energy splitting and TADF mechanism of the compounds. Both compounds showed similar singlet excited states that originated from the charge transfer (CT) states (1 CT), whereas the triplet excited states were tuned by the heteroatom in the donor unit. The origin of phosphorescence in the BTICNTrz emitter was CT emission from the triplet state (3 CT), whereas that in the BFICNTrz emitter stemmed from the local triplet excited state (3 LE). Consequently, BTICNTrz showed a small singlet-triplet energy splitting of 0.08 eV, compared with 0.26 eV for BFICNTrz. Thus, BTICNTrz showed efficient delayed fluorescence with a high quantum yield and a short delayed exciton lifetime, whereas BFICNTrz displayed weak delayed fluorescence with a relatively long lifetime. Furthermore, a BTICNTrz-based device exhibited a maximum external quantum efficiency (EQE) of 15.2 % and reduced efficiency roll-off (12 %) compared with its BFICNTrz-based counterpart, which showed a maximum EQE of 6.4 % and severe efficiency roll-off (55 %) at a practical brightness range of 1000 cd m-2 . These results demonstrate that the choice of subunit plays a vital role in the design of efficient TADF emitters.
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Affiliation(s)
- Rajendra Kumar Konidena
- School of Chemical Engineering, Sungkyunkwan University, 2066 Seobu-ro, Jangan-gu, Suwon, Gyeonggi, 440-746, Korea
| | - Kyung Hyung Lee
- School of Chemical Engineering, Sungkyunkwan University, 2066 Seobu-ro, Jangan-gu, Suwon, Gyeonggi, 440-746, Korea
| | - Jun Yeob Lee
- School of Chemical Engineering, Sungkyunkwan University, 2066 Seobu-ro, Jangan-gu, Suwon, Gyeonggi, 440-746, Korea
| | - Wan Pyo Hong
- LG Chem, Ltd, LG Science Park, 30, Magokjungang 10-ro, Gangseo-gu, Seoul, 07796, Republic of Korea
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De J, Yang WY, Bala I, Gupta SP, Yadav RAK, Dubey DK, Chowdhury A, Jou JH, Pal SK. Room-Temperature Columnar Liquid Crystals as Efficient Pure Deep-Blue Emitters in Organic Light-Emitting Diodes with an External Quantum Efficiency of 4.0. ACS APPLIED MATERIALS & INTERFACES 2019; 11:8291-8300. [PMID: 30707013 DOI: 10.1021/acsami.8b18749] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
A novel design of aggregation-induced emission (AIE) active columnar (Col) luminomesogens is reported, and they are demonstrated to act as highly efficient deep-blue emitters in organic light-emitting diodes (OLEDs). All derivatives exhibit Col liquid crystalline (LC) behavior at room temperature over a wide temperature range and desirable alignment properties, which is very important in using them as materials for organic electronic devices. These new AIE active luminomesogens were found to act as highly efficient emitters in OLEDs and unveiled a maximum external quantum efficiency of 4.0% for the first time in Col LCs with Commission International de l'E'clairage coordinates of (0.17, 0.07), which closely matches the National Television System Committee (NTSC) standard, corresponding to pure deep blue color. The detailed supramolecular assembly of the compounds has been characterized by modeling in the mesophase derived from small- and wide-angle X-ray scattering results.
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Affiliation(s)
- Joydip De
- Department of Chemical Sciences , Indian Institute of Science Education and Research (IISER) Mohali , Sector-81, SAS Nagar, Knowledge City , Manauli 140306 , India
| | - Wan-Yun Yang
- Department of Materials Science and Engineering , National Tsing Hua University , Hsinchu 30013 , Taiwan
| | - Indu Bala
- Department of Chemical Sciences , Indian Institute of Science Education and Research (IISER) Mohali , Sector-81, SAS Nagar, Knowledge City , Manauli 140306 , India
| | | | - Rohit Ashok Kumar Yadav
- Department of Materials Science and Engineering , National Tsing Hua University , Hsinchu 30013 , Taiwan
| | - Deepak Kumar Dubey
- Department of Materials Science and Engineering , National Tsing Hua University , Hsinchu 30013 , Taiwan
| | - Arjun Chowdhury
- Department of Chemical Sciences , Indian Institute of Science Education and Research (IISER) Mohali , Sector-81, SAS Nagar, Knowledge City , Manauli 140306 , India
| | - Jwo-Huei Jou
- Department of Materials Science and Engineering , National Tsing Hua University , Hsinchu 30013 , Taiwan
| | - Santanu Kumar Pal
- Department of Chemical Sciences , Indian Institute of Science Education and Research (IISER) Mohali , Sector-81, SAS Nagar, Knowledge City , Manauli 140306 , India
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